diff --git a/.phive/phars.xml b/.phive/phars.xml
index 980defa..b2b9a1e 100644
--- a/.phive/phars.xml
+++ b/.phive/phars.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phive xmlns="https://phar.io/phive">
-  <phar name="psalm" version="^4.13.1" installed="4.13.1" location="./tools/psalm.phar" copy="true"/>
+  <phar name="psalm" version="^4.19.0" installed="4.19.0" location="./tools/psalm.phar" copy="true"/>
   <phar name="php-cs-fixer" version="^3.3.2" installed="3.3.2" location="./tools/php-cs-fixer.phar" copy="true"/>
 </phive>
diff --git a/README.md b/README.md
index e07f52c..f718ffc 100644
--- a/README.md
+++ b/README.md
@@ -56,6 +56,21 @@ $loader = new StreamWrapperLoader(
 $contents = $loader($wsdl);
 ```
 
+### FlatteningLoader
+
+This loader can be used if your WSDL file contains WSDL or XSD imports.
+It will any other loader internally to load all the parts.
+The result of this loader is a completely flattened WSDL file which you can e.g. cache on your local filesystem.
+
+```php
+use Soap\Wsdl\Loader\FlatteningLoader;
+use Soap\Wsdl\Loader\StreamWrapperLoader;
+
+$loader = new FlatteningLoader(new StreamWrapperLoader());
+
+$contents = $loader($wsdl);
+```
+
 
 ## WSDL Validators
 
@@ -92,4 +107,3 @@ $wsdl = Document::fromXmlString((new StreamWrapperLoader())($file));
 echo "Validating WSDL:".PHP_EOL;
 $issues = $wsdl->validate(new Validator\WsdlSyntaxValidator());
 echo ($issues->count() ? $issues->toString() : '🟢 ALL GOOD').PHP_EOL;
-```
diff --git a/composer.json b/composer.json
index 4d39d27..54d3be5 100644
--- a/composer.json
+++ b/composer.json
@@ -21,8 +21,12 @@
     ],
     "require": {
         "php": "^8.0",
+        "ext-dom": "*",
+        "azjezz/psl": "^1.9",
+        "league/uri": "^6.5",
+        "league/uri-components": "^2.4",
         "php-soap/xml": "^1.2",
-        "veewee/xml": "^1.1"
+        "veewee/xml": "~1.2"
     },
     "require-dev": {
         "phpunit/phpunit": "^9.5"
diff --git a/phpunit.xml b/phpunit.xml
index 07df353..c3059d4 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,4 +1,8 @@
-<phpunit bootstrap="./tests/bootstrap.php" colors="true">
+<phpunit
+    bootstrap="./tests/bootstrap.php"
+    colors="true"
+    convertDeprecationsToExceptions="false"
+>
     <testsuites>
         <testsuite name="Unit">
             <directory>./tests/Unit</directory>
diff --git a/psalm.xml b/psalm.xml
index 539e13c..8d4bba4 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -2,7 +2,6 @@
 <psalm
     errorLevel="1"
     resolveFromConfigFile="true"
-    forbidEcho="true"
     strictBinaryOperands="true"
     phpVersion="8.0"
     allowStringToStandInForClass="true"
@@ -21,4 +20,8 @@
             <directory name="tests" />
         </ignoreFiles>
     </projectFiles>
+    <ignoreExceptions>
+        <class name="InvalidArgumentException" />
+        <class name="Psl\Exception\InvariantViolationException" />
+    </ignoreExceptions>
 </psalm>
diff --git a/src/Loader/Context/FlatteningContext.php b/src/Loader/Context/FlatteningContext.php
new file mode 100644
index 0000000..545a902
--- /dev/null
+++ b/src/Loader/Context/FlatteningContext.php
@@ -0,0 +1,112 @@
+<?php
+declare(strict_types=1);
+
+namespace Soap\Wsdl\Loader\Context;
+
+use DOMElement;
+use Soap\Wsdl\Exception\UnloadableWsdlException;
+use Soap\Wsdl\Loader\WsdlLoader;
+use Soap\Wsdl\Xml\Configurator\FlattenTypes;
+use Soap\Wsdl\Xml\Flattener;
+use Soap\Xml\Xpath\WsdlPreset;
+use VeeWee\Xml\Dom\Document;
+use VeeWee\Xml\Exception\RuntimeException;
+use function VeeWee\Xml\Dom\Mapper\xml_string;
+
+final class FlatteningContext
+{
+    /**
+     * XSD import catalog of location => raw (not flattened) xml
+     *
+     * @var array<string, string>
+     */
+    private $catalog = [];
+
+    public static function forWsdl(
+        string $location,
+        Document $wsdl,
+        WsdlLoader $loader,
+    ): self {
+        $new = new self($wsdl, $loader);
+        $new->catalog[$location] = $wsdl->map(xml_string());
+
+        return $new;
+    }
+
+    private function __construct(
+        private Document $wsdl,
+        private WsdlLoader $loader
+    ) {
+    }
+
+    /**
+     * This function can be used to detect if the context knows about a part of the WSDL.
+     * It knows about a part from the moment that the raw XML version has been loaded once,
+     * even if the flattening process is still in an underlying import / include.
+     */
+    public function knowsAboutPart(string $location): bool
+    {
+        return array_key_exists($location, $this->catalog);
+    }
+
+    /**
+     * Imports and include only need to occur once.
+     * This function determines if an import should be done.
+     *
+     * It either returns null if the import already was done or the flattened XML if it still requires an import.
+     */
+    public function import(string $location): ?string
+    {
+        return $this->knowsAboutPart($location)
+            ? null
+            : $this->loadFlattenedXml($location);
+    }
+
+    /**
+     * Returns the base WSDL document that can be worked on by flattener configurators.
+     */
+    public function wsdl(): Document
+    {
+        return $this->wsdl;
+    }
+
+    /**
+     * This method searches for a single <wsdl:types /> tag
+     * If no tag exists, it will create an empty one.
+     * If multiple tags exist, it will merge those tags into one.
+     *
+     * @throws RuntimeException
+     */
+    public function types(): DOMElement
+    {
+        $doc = Document::fromUnsafeDocument($this->wsdl->toUnsafeDocument(), new FlattenTypes());
+        $xpath = $doc->xpath(new WsdlPreset($doc));
+
+        /** @var DOMElement $types */
+        $types = $xpath->querySingle('//wsdl:types');
+
+        return $types;
+    }
+
+    /**
+     * This function will take care of the import catalog!
+     * It will first load the raw xml from the remote source and store that internally.
+     *
+     * Next it will apply the XML flattening on the loaded xml and return the flattened string.
+     * We keep track of all nested flattening locations that are in progress.
+     * This way we can prevent circular includes as well.
+     *
+     * @throws UnloadableWsdlException
+     * @throws RuntimeException
+     */
+    private function loadFlattenedXml(string $location): string
+    {
+        if (!array_key_exists($location, $this->catalog)) {
+            $this->catalog[$location] = ($this->loader)($location);
+        }
+
+        $document = Document::fromXmlString($this->catalog[$location]);
+
+        return (new Flattener())($location, $document, $this);
+    }
+}
diff --git a/src/Loader/FlatteningLoader.php b/src/Loader/FlatteningLoader.php
new file mode 100644
index 0000000..d6fa33b
--- /dev/null
+++ b/src/Loader/FlatteningLoader.php
@@ -0,0 +1,30 @@
+<?php
+declare(strict_types=1);
+
+namespace Soap\Wsdl\Loader;
+
+use Soap\Wsdl\Exception\UnloadableWsdlException;
+use Soap\Wsdl\Loader\Context\FlatteningContext;
+use Soap\Wsdl\Xml\Flattener;
+use VeeWee\Xml\Dom\Document;
+use VeeWee\Xml\Exception\RuntimeException;
+
+final class FlatteningLoader implements WsdlLoader
+{
+    public function __construct(
+        private WsdlLoader $loader,
+    ) {
+    }
+
+    /**
+     * @throws RuntimeException
+     * @throws UnloadableWsdlException
+     */
+    public function __invoke(string $location): string
+    {
+        $currentDoc = Document::fromXmlString(($this->loader)($location));
+        $context = FlatteningContext::forWsdl($location, $currentDoc, $this->loader);
+
+        return (new Flattener())($location, $currentDoc, $context);
+    }
+}
diff --git a/src/Uri/IncludePathBuilder.php b/src/Uri/IncludePathBuilder.php
new file mode 100644
index 0000000..8b3db39
--- /dev/null
+++ b/src/Uri/IncludePathBuilder.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Soap\Wsdl\Uri;
+
+use League\Uri\Uri;
+use League\Uri\UriModifier;
+use League\Uri\UriResolver;
+
+final class IncludePathBuilder
+{
+    public static function build(string $relativePath, string $fromFile): string
+    {
+        return UriModifier::removeEmptySegments(
+            UriModifier::removeDotSegments(
+                UriResolver::resolve(
+                    Uri::createFromString($relativePath),
+                    Uri::createFromString($fromFile)
+                )
+            )
+        )->__toString();
+    }
+}
diff --git a/src/Xml/Configurator/FlattenTypes.php b/src/Xml/Configurator/FlattenTypes.php
new file mode 100644
index 0000000..21d3b7b
--- /dev/null
+++ b/src/Xml/Configurator/FlattenTypes.php
@@ -0,0 +1,61 @@
+<?php
+declare(strict_types=1);
+
+namespace Soap\Wsdl\Xml\Configurator;
+
+use DOMDocument;
+use DOMElement;
+use Soap\Xml\Xmlns;
+use Soap\Xml\Xpath\WsdlPreset;
+use VeeWee\Xml\Dom\Configurator\Configurator;
+use VeeWee\Xml\Dom\Document;
+use VeeWee\Xml\Exception\RuntimeException;
+use function VeeWee\Xml\Dom\Builder\namespaced_element;
+use function VeeWee\Xml\Dom\Locator\Node\children;
+use function VeeWee\Xml\Dom\Manipulator\append;
+use function VeeWee\Xml\Dom\Manipulator\Node\remove;
+
+/**
+ * This class transforms multiple wsdl:types elements into 1 single element.
+ * This makes importing xsd's easier (and prevents some bugs in some soap related tools)
+ */
+final class FlattenTypes implements Configurator
+{
+    /**
+     * @throws RuntimeException
+     */
+    public function __invoke(DOMDocument $document): DOMDocument
+    {
+        $xml = Document::fromUnsafeDocument($document);
+        $xpath = $xml->xpath(new WsdlPreset($xml));
+        /** @var list<DOMElement> $types */
+        $types = [...$xpath->query('wsdl:types')];
+
+        // Creates wsdl:types if no matching element exists yet
+        if (!count($types)) {
+            $document->documentElement->append(
+                namespaced_element(Xmlns::wsdl()->value(), 'types')($document)
+            );
+
+            return $document;
+        }
+
+        // Skip if only one exists
+        $first = array_shift($types);
+        if (!count($types)) {
+            return $document;
+        }
+
+        // Flattens multiple wsdl:types elements.
+        foreach ($types as $additionalTypes) {
+            $children = children($additionalTypes);
+            if (count($children)) {
+                append(...$children)($first);
+            }
+
+            remove($additionalTypes);
+        }
+
+        return $document;
+    }
+}
diff --git a/src/Xml/Configurator/FlattenWsdlImports.php b/src/Xml/Configurator/FlattenWsdlImports.php
new file mode 100644
index 0000000..531cbde
--- /dev/null
+++ b/src/Xml/Configurator/FlattenWsdlImports.php
@@ -0,0 +1,76 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Soap\Wsdl\Xml\Configurator;
+
+use DOMDocument;
+use DOMElement;
+use Soap\Wsdl\Exception\UnloadableWsdlException;
+use Soap\Wsdl\Loader\Context\FlatteningContext;
+use Soap\Wsdl\Uri\IncludePathBuilder;
+use Soap\Xml\Xpath\WsdlPreset;
+use VeeWee\Xml\Dom\Configurator\Configurator;
+use VeeWee\Xml\Dom\Document;
+use VeeWee\Xml\Exception\RuntimeException;
+use function VeeWee\Xml\Dom\Locator\document_element;
+use function VeeWee\Xml\Dom\Locator\Node\children;
+use function VeeWee\Xml\Dom\Manipulator\Node\remove;
+use function VeeWee\Xml\Dom\Manipulator\Node\replace_by_external_nodes;
+
+final class FlattenWsdlImports implements Configurator
+{
+    public function __construct(
+        private string $currentLocation,
+        private FlatteningContext $context
+    ) {
+    }
+
+    /**
+     * This method flattens wsdl:import locations.
+     * It loads the WSDL and adds the definitions replaces the import tag with the definition children from the external file.
+     *
+     * For now, we don't care about the namespace property on the wsdl:import tag.
+     * Future reference:
+     * @link http://itdoc.hitachi.co.jp/manuals/3020/30203Y2310e/EY230669.HTM#ID01496
+     *
+     * @throws RuntimeException
+     * @throws UnloadableWsdlException
+     */
+    public function __invoke(DOMDocument $document): DOMDocument
+    {
+        $xml = Document::fromUnsafeDocument($document);
+        $xpath = $xml->xpath(new WsdlPreset($xml));
+
+        $imports = $xpath->query('wsdl:import');
+        $imports->forEach(fn (DOMElement $import) => $this->importWsdlImportElement($import));
+
+        return $document;
+    }
+
+    /**
+     * @throws RuntimeException
+     * @throws UnloadableWsdlException
+     */
+    private function importWsdlImportElement(DOMElement $import): void
+    {
+        $location = IncludePathBuilder::build(
+            $import->getAttribute('location'),
+            $this->currentLocation
+        );
+
+        $result = $this->context->import($location);
+        if (!$result) {
+            remove($import);
+            return;
+        }
+
+        $imported = Document::fromXmlString($result);
+        $definitions = $imported->map(document_element());
+
+        replace_by_external_nodes(
+            $import,
+            children($definitions)
+        );
+    }
+}
diff --git a/src/Xml/Configurator/FlattenXsdImports.php b/src/Xml/Configurator/FlattenXsdImports.php
new file mode 100644
index 0000000..905d4ee
--- /dev/null
+++ b/src/Xml/Configurator/FlattenXsdImports.php
@@ -0,0 +1,203 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Soap\Wsdl\Xml\Configurator;
+
+use DOMDocument;
+use DOMElement;
+use DOMNode;
+use Psl\Type\Exception\AssertException;
+use Soap\Wsdl\Exception\UnloadableWsdlException;
+use Soap\Wsdl\Loader\Context\FlatteningContext;
+use Soap\Wsdl\Uri\IncludePathBuilder;
+use Soap\Wsdl\Xml\Exception\FlattenException;
+use Soap\Xml\Xpath\WsdlPreset;
+use VeeWee\Xml\Dom\Configurator\Configurator;
+use VeeWee\Xml\Dom\Document;
+use VeeWee\Xml\Exception\RuntimeException;
+use function Psl\Type\nullable;
+use function Psl\Type\object;
+use function VeeWee\Xml\Dom\Locator\Node\children;
+use function VeeWee\Xml\Dom\Manipulator\Element\copy_named_xmlns_attributes;
+use function VeeWee\Xml\Dom\Manipulator\Node\append_external_node;
+use function VeeWee\Xml\Dom\Manipulator\Node\remove;
+
+/**
+ * This class deals with xsd:import, xsd:include and xsd:redefine tags.
+ * It imports the types grouped by schema namespace to make sure that the size of the result is as small as possible!
+ */
+final class FlattenXsdImports implements Configurator
+{
+    public function __construct(
+        private string $currentLocation,
+        private FlatteningContext $context
+    ) {
+    }
+
+    /**
+     * @throws RuntimeException
+     * @throws UnloadableWsdlException
+     * @throws FlattenException
+     */
+    public function __invoke(DOMDocument $document): DOMDocument
+    {
+        $xml = Document::fromUnsafeDocument($document);
+        $xpath = $xml->xpath(new WsdlPreset($xml));
+
+        $imports = $xpath
+            ->query('//schema:import|//schema:include|//schema:redefine')
+            ->expectAllOfType(DOMElement::class);
+
+        if (!count($imports)) {
+            return $document;
+        }
+
+        foreach ($imports as $import) {
+            $schema = match ($import->localName) {
+                'include', 'redefine' => $this->includeSchema($import),
+                'import' => $this->importSchema($import),
+            };
+
+            if ($schema) {
+                $this->registerSchemaInTypes($schema);
+            }
+        }
+
+        return $document;
+    }
+
+    /**
+     * @throws RuntimeException
+     * @throws UnloadableWsdlException
+     * @throws FlattenException
+     */
+    private function includeSchema(DOMElement $include): ?DOMElement
+    {
+        // All includes and redefines require a schemLocation attribute
+        if (!$location = $include->getAttribute('schemaLocation')) {
+            throw FlattenException::noLocation($include->localName);
+        }
+
+        /*
+         * Currently we do not validate the namespace of includes - we assume the provided imports are valid!
+         *
+         * @see https://docs.microsoft.com/en-us/previous-versions/dotnet/netframework-4.0/ms256198(v=vs.100)
+         * The included schema document must meet one of the following conditions.
+            -    It must have the same target namespace as the containing schema document.
+            -    It must not have a target namespace specified (no targetNamespace attribute).
+         */
+
+        $schema = $this->loadSchema($location);
+
+        // Redefines overwrite tags from includes.
+        // The children of redefine elements are appended to the newly loaded schema.
+        if ($schema && $include->localName === 'redefine') {
+            children($include)->map(
+                static fn (DOMNode $node) => append_external_node($schema, $node)
+            );
+        }
+
+        // Include tags can be removed, since the schema will be made available in the types
+        // using the namespace it defines. The include/redefine tag will have no purpose anymore.
+        remove($include);
+
+        return $schema;
+    }
+
+    /**
+     * @throws RuntimeException
+     * @throws UnloadableWsdlException
+     * @throws FlattenException
+     */
+    private function importSchema(DOMElement $import): ?DOMElement
+    {
+        // xsd:import tags don't require a location!
+        $location = $import->getAttribute('schemaLocation');
+        if (!$location) {
+            return null;
+        }
+
+        // Normally an import has an owner document, since it is coming from xpath on an existing document
+        // However, static analysis does not know about this.
+        if (!$import->ownerDocument) {
+            return null;
+        }
+
+        // Find the schema that wants to import the new schema:
+        $doc = Document::fromUnsafeDocument($import->ownerDocument);
+        $xpath = $doc->xpath(new WsdlPreset($doc));
+        /** @var DOMElement $schema */
+        $schema = $xpath->querySingle('ancestor::schema:schema', $import);
+
+        // Detect namespaces from both the current schema and the import
+        $namespace = $import->getAttribute('namespace');
+        $tns = $schema->getAttribute('targetNamespace');
+
+        // Imports can only deal with different namespaces.
+        // You'll need to use "include" if you want to inject something in the same namespace.
+        if ($tns && $namespace && $tns === $namespace) {
+            throw FlattenException::unableToImportXsd($location);
+        }
+
+        // After loading the schema, the import element needs to remain in the XSD.
+        // The schema location is removed, since it will be embedded in the WSDL.
+        $schema = $this->loadSchema($location);
+        $import->removeAttribute('schemaLocation');
+
+        return $schema;
+    }
+
+    /**
+     * @throws RuntimeException
+     * @throws UnloadableWsdlException
+     */
+    private function loadSchema(string $location): ?DOMElement
+    {
+        $path = IncludePathBuilder::build($location, $this->currentLocation);
+        $result = $this->context->import($path);
+
+        if (!$result) {
+            return null;
+        }
+
+        $imported = Document::fromXmlString($result);
+        /** @var DOMElement $schema */
+        $schema = $imported->xpath(new WsdlPreset($imported))->querySingle('/schema:schema');
+
+        return $schema;
+    }
+
+    /**
+     * This function registers the newly provided schema in the WSDL types section.
+     * It groups all imports by targetNamespace.
+     *
+     * @throws RuntimeException
+     * @throws AssertException
+     */
+    private function registerSchemaInTypes(DOMElement $schema): void
+    {
+        $wsdl = $this->context->wsdl();
+        $xpath = $wsdl->xpath(new WsdlPreset($wsdl));
+        $types = $this->context->types();
+        $tns = $schema->getAttribute('targetNamespace');
+
+        $query = $tns ? './schema:schema[@targetNamespace=\''.$tns.'\']' : './schema:schema[not(@targetNamespace)]';
+        $existingSchema = nullable(object(DOMElement::class))
+            ->assert($xpath->query($query, $types)->first());
+
+        // If no schema exists yet: Add the newly loaded schema as a completely new schema in the WSDL types.
+        if (!$existingSchema) {
+            append_external_node($types, $schema);
+            return;
+        }
+
+        // When an existing schema exists, all xmlns attributes need to be copied.
+        // This is to make sure that possible QNames (strings) get resolved in XSD.
+        // Finally - all children of the newly loaded schema can be appended to the existing schema.
+        copy_named_xmlns_attributes($existingSchema, $schema);
+        children($schema)->forEach(
+            static fn (DOMNode $node) => append_external_node($existingSchema, $node)
+        );
+    }
+}
diff --git a/src/Xml/Exception/FlattenException.php b/src/Xml/Exception/FlattenException.php
new file mode 100644
index 0000000..dab9ec5
--- /dev/null
+++ b/src/Xml/Exception/FlattenException.php
@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Soap\Wsdl\Xml\Exception;
+
+use RuntimeException;
+
+final class FlattenException extends RuntimeException
+{
+    public static function noLocation(string $elementName): self
+    {
+        return new self("Parsing Schema: {$elementName} has no 'schemaLocation' attribute");
+    }
+
+    public static function unableToImportXsd(string $location): self
+    {
+        $target = $location ? ' from '.$location : '';
+
+        return new self("Parsing Schema: can't import schema{$target}. Namespace must not match the enclosing schema 'targetNamespace'");
+    }
+}
diff --git a/src/Xml/Flattener.php b/src/Xml/Flattener.php
new file mode 100644
index 0000000..c98ced7
--- /dev/null
+++ b/src/Xml/Flattener.php
@@ -0,0 +1,44 @@
+<?php
+declare(strict_types=1);
+
+namespace Soap\Wsdl\Xml;
+
+use Closure;
+use DOMDocument;
+use Soap\Wsdl\Loader\Context\FlatteningContext;
+use Soap\Wsdl\Xml\Configurator\FlattenTypes;
+use Soap\Wsdl\Xml\Configurator\FlattenWsdlImports;
+use Soap\Wsdl\Xml\Configurator\FlattenXsdImports;
+use VeeWee\Xml\Dom\Document;
+use VeeWee\Xml\Exception\RuntimeException;
+use function Psl\Fun\pipe;
+use function Psl\Fun\when;
+use function VeeWee\Xml\Dom\Configurator\utf8;
+
+final class Flattener
+{
+    /**
+     * @throws RuntimeException
+     */
+    public function __invoke(
+        string $location,
+        Document $document,
+        FlatteningContext $context
+    ): string {
+        return Document::fromUnsafeDocument(
+            $document->toUnsafeDocument(),
+            pipe(
+                utf8(),
+                when(
+                    static fn (DOMDocument $document): bool => $document->documentElement->localName === 'definitions',
+                    pipe(
+                        Closure::fromCallable(new FlattenWsdlImports($location, $context)),
+                        Closure::fromCallable(new FlattenTypes()),
+                        Closure::fromCallable(new FlattenXsdImports($location, $context)),
+                    ),
+                    Closure::fromCallable(new FlattenXsdImports($location, $context))
+                )
+            )
+        )->toXmlString();
+    }
+}
diff --git a/tests/Unit/Loader/FlatteningLoaderTest.php b/tests/Unit/Loader/FlatteningLoaderTest.php
new file mode 100644
index 0000000..65d120c
--- /dev/null
+++ b/tests/Unit/Loader/FlatteningLoaderTest.php
@@ -0,0 +1,103 @@
+<?php
+declare(strict_types=1);
+
+namespace Soap\Wsdl\Test\Unit\Loader;
+
+use PHPUnit\Framework\TestCase;
+use Soap\Wsdl\Loader\FlatteningLoader;
+use Soap\Wsdl\Loader\StreamWrapperLoader;
+use VeeWee\Xml\Dom\Document;
+use function VeeWee\Xml\Dom\Configurator\comparable;
+
+final class FlatteningLoaderTest extends TestCase
+{
+    private FlatteningLoader $loader;
+
+    protected function setUp(): void
+    {
+        $this->loader = new FlatteningLoader(new StreamWrapperLoader());
+    }
+
+    /**
+     *
+     * @dataProvider provideTestCases
+     */
+    public function test_it_can_load_flattened_imports(string $wsdlUri, Document $expected): void
+    {
+        $result = ($this->loader)($wsdlUri);
+        $flattened = Document::fromXmlString($result, comparable());
+
+        static::assertSame($expected->toXmlString(), $flattened->toXmlString());
+    }
+
+    public function provideTestCases()
+    {
+        //
+        // Basic test cases
+        //
+        yield 'no-imports' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/functional/float.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/functional/float.wsdl', comparable()),
+        ];
+        yield 'circular-xsd' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/circular-xsd.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/circular-xsd-result.wsdl', comparable()),
+        ];
+        yield 'importing-circular-xsd' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/importing-circular-xsd.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/importing-circular-xsd-result.wsdl', comparable()),
+        ];
+
+        //
+        // XSDs Imports
+        //
+        yield 'single-xsd' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/single-xsd.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/single-xsd-result.wsdl', comparable()),
+        ];
+        yield 'import-once-xsd' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/once-xsd.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/once-xsd-result.wsdl', comparable()),
+        ];
+        yield 'import-multi-xsd' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/multi-xsd.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/multi-xsd-result.wsdl', comparable()),
+        ];
+
+        //
+        // XSD Includes
+        //
+        yield 'include-single' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/include.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/include.wsdl', comparable()),
+        ];
+        yield 'include-multi' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/multi-include.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/multi-include.wsdl', comparable()),
+        ];
+        yield 'include-nested' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/include-nested.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/include.wsdl', comparable()),
+        ];
+        yield 'imported-include-nested' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/include-nested.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/include.wsdl', comparable()),
+        ];
+        yield 'include-additional-namespaces' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/include-namespaces.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/include-namespaces.wsdl', comparable()),
+        ];
+
+        //
+        // WSDLs
+        //
+        yield 'only-wsdl-import' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/import.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/functional/float.wsdl', comparable()),
+        ];
+        yield 'import-wsdl-once' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/import.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/functional/float.wsdl', comparable()),
+        ];
+    }
+}
diff --git a/tests/Unit/Uri/IncludePathBuilderTest.php b/tests/Unit/Uri/IncludePathBuilderTest.php
new file mode 100644
index 0000000..ea73708
--- /dev/null
+++ b/tests/Unit/Uri/IncludePathBuilderTest.php
@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Soap\Wsdl\Test\Unit\Uri;
+
+use PHPUnit\Framework\TestCase;
+use Soap\Wsdl\Uri\IncludePathBuilder;
+
+final class IncludePathBuilderTest extends TestCase
+{
+    /**
+     *
+     * @dataProvider provideBuildPaths
+     */
+    public function test_it_can_build_include_paths(string $relativePath, string $fromFile, string $expected): void
+    {
+        static::assertSame($expected, IncludePathBuilder::build($relativePath, $fromFile));
+    }
+
+    public function provideBuildPaths()
+    {
+        yield 'same-dir-file' => [
+            'relativePath' => 'otherfile.xml',
+            'fromFile' => 'somedir/somefile.xml',
+            'expected' => 'somedir/otherfile.xml',
+        ];
+        yield 'child-dir-file' => [
+            'relativePath' => '../otherfile.xml',
+            'fromFile' => 'somedir/child/somefile.xml',
+            'expected' => 'somedir/otherfile.xml',
+        ];
+        yield 'http-file' => [
+            'relativePath' => 'otherfile.xml',
+            'fromFile' => 'http://localhost/somedir/somefile.xml',
+            'expected' => 'http://localhost/somedir/otherfile.xml',
+        ];
+        yield 'http-dir-file' => [
+            'relativePath' => '../otherfile.xml',
+            'fromFile' => 'http://localhost/somedir/child/somefile.xml',
+            'expected' => 'http://localhost/somedir/otherfile.xml',
+        ];
+    }
+}
diff --git a/tests/Unit/Xml/Configurator/FlattenTypesTest.php b/tests/Unit/Xml/Configurator/FlattenTypesTest.php
new file mode 100644
index 0000000..ad420a4
--- /dev/null
+++ b/tests/Unit/Xml/Configurator/FlattenTypesTest.php
@@ -0,0 +1,39 @@
+<?php
+declare(strict_types=1);
+
+namespace Soap\Wsdl\Test\Unit\Xml\Configurator;
+
+use PHPUnit\Framework\TestCase;
+use Soap\Wsdl\Xml\Configurator\FlattenTypes;
+use VeeWee\Xml\Dom\Document;
+use function VeeWee\Xml\Dom\Configurator\comparable;
+
+final class FlattenTypesTest extends TestCase
+{
+    /**
+     *
+     * @dataProvider provideTestCases
+     */
+    public function test_it_can_flatten_types(string $wsdlUri, Document $expected): void
+    {
+        $wsdl = Document::fromXmlFile($wsdlUri, new FlattenTypes(), comparable());
+
+        static::assertSame($expected->toXmlString(), $wsdl->toXmlString());
+    }
+
+    public function provideTestCases()
+    {
+        yield 'single-type' => [
+            'wsdl' => FIXTURE_DIR . '/flattening/functional/empty-schema.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR . '/flattening/functional/empty-schema.wsdl', comparable()),
+        ];
+        yield 'no-type' => [
+            'wsdl' => FIXTURE_DIR . '/flattening/functional/empty.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR . '/flattening/result/empty-typed.wsdl', comparable()),
+        ];
+        yield 'multiple-types' => [
+            'wsdl' => FIXTURE_DIR . '/flattening/result/import-with-own-tags-result.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR . '/flattening/result/import-with-own-tags-single-type-result.wsdl', comparable()),
+        ];
+    }
+}
diff --git a/tests/Unit/Xml/Configurator/FlattenWsdlImportsTest.php b/tests/Unit/Xml/Configurator/FlattenWsdlImportsTest.php
new file mode 100644
index 0000000..a482ddb
--- /dev/null
+++ b/tests/Unit/Xml/Configurator/FlattenWsdlImportsTest.php
@@ -0,0 +1,50 @@
+<?php
+declare(strict_types=1);
+
+namespace Soap\Wsdl\Test\Unit\Xml\Configurator;
+
+use PHPUnit\Framework\TestCase;
+use Soap\Wsdl\Loader\Context\FlatteningContext;
+use Soap\Wsdl\Loader\StreamWrapperLoader;
+use Soap\Wsdl\Xml\Configurator\FlattenWsdlImports;
+use VeeWee\Xml\Dom\Document;
+use function VeeWee\Xml\Dom\Configurator\comparable;
+
+final class FlattenWsdlImportsTest extends TestCase
+{
+    /**
+     *
+     * @dataProvider provideTestCases
+     */
+    public function test_it_can_flatten_wsdl_imports(string $wsdlUri, Document $expected): void
+    {
+        $wsdl = Document::fromXmlFile($wsdlUri);
+        $configurator = new FlattenWsdlImports(
+            $wsdlUri,
+            FlatteningContext::forWsdl($wsdlUri, $wsdl, new StreamWrapperLoader())
+        );
+        $flattened = Document::fromUnsafeDocument($wsdl->toUnsafeDocument(), $configurator, comparable());
+
+        static::assertSame($expected->toXmlString(), $flattened->toXmlString());
+    }
+
+    public function provideTestCases()
+    {
+        yield 'only-import' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/import.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/functional/float.wsdl', comparable()),
+        ];
+        yield 'import-once' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/import.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/functional/float.wsdl', comparable()),
+        ];
+        yield 'with-own-tags' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/import-with-own-tags.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/import-with-own-tags-result.wsdl', comparable()),
+        ];
+        yield 'multi-imports' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/multi-import.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/multi-import-result.wsdl', comparable()),
+        ];
+    }
+}
diff --git a/tests/Unit/Xml/Configurator/FlattenXsdImportsTest.php b/tests/Unit/Xml/Configurator/FlattenXsdImportsTest.php
new file mode 100644
index 0000000..9d9ae90
--- /dev/null
+++ b/tests/Unit/Xml/Configurator/FlattenXsdImportsTest.php
@@ -0,0 +1,62 @@
+<?php
+declare(strict_types=1);
+
+namespace Soap\Wsdl\Test\Unit\Xml\Configurator;
+
+use PHPUnit\Framework\TestCase;
+use Soap\Wsdl\Loader\Context\FlatteningContext;
+use Soap\Wsdl\Loader\StreamWrapperLoader;
+use Soap\Wsdl\Xml\Configurator\FlattenXsdImports;
+use VeeWee\Xml\Dom\Document;
+use function VeeWee\Xml\Dom\Configurator\comparable;
+
+final class FlattenXsdImportsTest extends TestCase
+{
+    /**
+     *
+     * @dataProvider provideTestCases
+     */
+    public function test_it_can_flatten_xsd_imports(string $wsdlUri, Document $expected): void
+    {
+        $wsdl = Document::fromXmlFile($wsdlUri);
+        $configurator = new FlattenXsdImports(
+            $wsdlUri,
+            FlatteningContext::forWsdl($wsdlUri, $wsdl, new StreamWrapperLoader())
+        );
+        $flattened = Document::fromUnsafeDocument($wsdl->toUnsafeDocument(), $configurator, comparable());
+
+        static::assertSame($expected->toXmlString(), $flattened->toXmlString());
+    }
+
+    public function provideTestCases()
+    {
+        yield 'single-xsd' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/single-xsd.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/single-xsd-result.wsdl', comparable()),
+        ];
+        yield 'once-xsd' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/once-xsd.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/once-xsd-result.wsdl', comparable()),
+        ];
+        yield 'multi-xsd' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/multi-xsd.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/multi-xsd-result.wsdl', comparable()),
+        ];
+        yield 'circular-xsd' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/circular-xsd.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/circular-xsd-result.wsdl', comparable()),
+        ];
+        yield 'redefine-xsd' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/redefine-xsd.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/redefine-xsd-result.wsdl', comparable()),
+        ];
+        yield 'tnsless-xsd' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/tnsless-xsd.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/tnsless-xsd-result.wsdl', comparable()),
+        ];
+        yield 'grouped-xsd' => [
+            'wsdl' => FIXTURE_DIR.'/flattening/grouped-xsd.wsdl',
+            'expected' => Document::fromXmlFile(FIXTURE_DIR.'/flattening/result/grouped-xsd-result.wsdl', comparable()),
+        ];
+    }
+}
diff --git a/tests/fixtures/flattening/circular-xsd.wsdl b/tests/fixtures/flattening/circular-xsd.wsdl
new file mode 100644
index 0000000..843b47b
--- /dev/null
+++ b/tests/fixtures/flattening/circular-xsd.wsdl
@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<definitions name="InteropTest"
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    xmlns="http://schemas.xmlsoap.org/wsdl/"
+    targetNamespace="http://soapinterop.org/">
+    <types>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/xsd">
+            <xsd:import schemaLocation="xsd/circular.xsd" namespace="http://soapinterop.org/circular" />
+            <xsd:import schemaLocation="xsd/circular-common.xsd" namespace="http://soapinterop.org/circular-common" />
+        </schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/duplicate-typenames.wsdl b/tests/fixtures/flattening/duplicate-typenames.wsdl
new file mode 100644
index 0000000..b8c503c
--- /dev/null
+++ b/tests/fixtures/flattening/duplicate-typenames.wsdl
@@ -0,0 +1,51 @@
+<?xml version="1.0"?>
+<definitions name="InteropTest"
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    xmlns:tns="http://soapinterop.org/"
+    xmlns:s1="http://soapinterop.org/xsd1"
+    xmlns:s2="http://soapinterop.org/xsd2"
+    xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
+    xmlns="http://schemas.xmlsoap.org/wsdl/"
+    targetNamespace="http://soapinterop.org/">
+    <types>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/xsd">
+            <xsd:import schemaLocation="xsd/store1.xsd" namespace="http://soapinterop.org/store1" />
+            <xsd:import schemaLocation="xsd/store2.xsd" namespace="http://soapinterop.org/store2" />
+        </schema>
+    </types>
+
+    <message name="validateRequest">
+        <part name="input1" type="s1:Store" />
+        <part name="input2" type="s2:Store" />
+    </message>
+    <message name="validateResponse">
+        <part name="output1" type="s1:Store" />
+        <part name="output2" type="s2:Store" />
+    </message>
+
+    <portType name="InteropTestPortType">
+        <operation name="validate">
+            <input message="tns:validateRequest"/>
+            <output message="tns:validateResponse"/>
+        </operation>
+    </portType>
+
+    <binding name="InteropTestBinding" type="tns:InteropTestPortType">
+        <soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/>
+        <operation name="validate">
+            <soap:operation soapAction="http://" style="rpc"/>
+            <input>
+                <soap:body use="encoded" namespace="http://soapinterop.org/" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>
+            </input>
+            <output>
+                <soap:body use="encoded" namespace="http://soapinterop.org/" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>
+            </output>
+        </operation>
+    </binding>
+
+    <service name="InteropTest">
+        <port name="InteropTestPort" binding="tns:InteropTestBinding">
+            <soap:address location="http://soapinterop.org/"/>
+        </port>
+    </service>
+</definitions>
diff --git a/tests/fixtures/flattening/functional/empty-schema.wsdl b/tests/fixtures/flattening/functional/empty-schema.wsdl
new file mode 100644
index 0000000..2218d08
--- /dev/null
+++ b/tests/fixtures/flattening/functional/empty-schema.wsdl
@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+        xmlns:tns="http://soapinterop.org/"
+        xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        targetNamespace="http://soapinterop.org/">
+
+    <types>
+        <xsd:schema />
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/functional/empty.wsdl b/tests/fixtures/flattening/functional/empty.wsdl
new file mode 100644
index 0000000..0ade329
--- /dev/null
+++ b/tests/fixtures/flattening/functional/empty.wsdl
@@ -0,0 +1,9 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+        xmlns:tns="http://soapinterop.org/"
+        xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        targetNamespace="http://soapinterop.org/">
+
+</definitions>
diff --git a/tests/fixtures/flattening/functional/float.wsdl b/tests/fixtures/flattening/functional/float.wsdl
new file mode 100644
index 0000000..113f995
--- /dev/null
+++ b/tests/fixtures/flattening/functional/float.wsdl
@@ -0,0 +1,45 @@
+<?xml version="1.0"?>
+<definitions
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    xmlns:tns="http://soapinterop.org/"
+    xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
+    xmlns="http://schemas.xmlsoap.org/wsdl/"
+    targetNamespace="http://soapinterop.org/">
+
+    <types>
+        <xsd:schema />
+    </types>
+
+    <message name="validateRequest">
+        <part name="input" type="xsd:float" />
+    </message>
+    <message name="validateResponse">
+        <part name="output" type="xsd:float" />
+    </message>
+
+    <portType name="InteropTestPortType">
+        <operation name="validate">
+            <input message="tns:validateRequest"/>
+            <output message="tns:validateResponse"/>
+        </operation>
+    </portType>
+
+    <binding name="InteropTestBinding" type="tns:InteropTestPortType">
+        <soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/>
+        <operation name="validate">
+            <soap:operation soapAction="http://soapinterop.org/validate" style="rpc"/>
+            <input>
+                <soap:body use="encoded" namespace="http://soapinterop.org/" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>
+            </input>
+            <output>
+                <soap:body use="encoded" namespace="http://soapinterop.org/" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>
+            </output>
+        </operation>
+    </binding>
+
+    <service name="InteropTest">
+        <port name="InteropTestPort" binding="tns:InteropTestBinding">
+            <soap:address location="http://soapinterop.org/"/>
+        </port>
+    </service>
+</definitions>
diff --git a/tests/fixtures/flattening/grouped-xsd.wsdl b/tests/fixtures/flattening/grouped-xsd.wsdl
new file mode 100644
index 0000000..658a712
--- /dev/null
+++ b/tests/fixtures/flattening/grouped-xsd.wsdl
@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<definitions name="InteropTest"
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    xmlns="http://schemas.xmlsoap.org/wsdl/"
+    targetNamespace="http://soapinterop.org/">
+    <types>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/xsd">
+            <xsd:import schemaLocation="xsd/store1.xsd" namespace="http://soapinterop.org/store1" />
+            <xsd:import schemaLocation="xsd/store1-extras.xsd" namespace="http://soapinterop.org/store1" />
+        </schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/import-once.wsdl b/tests/fixtures/flattening/import-once.wsdl
new file mode 100644
index 0000000..273a09b
--- /dev/null
+++ b/tests/fixtures/flattening/import-once.wsdl
@@ -0,0 +1,9 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/">
+    <import namespace="http://soapinterop.org/" location="functional/float.wsdl" />
+    <import namespace="http://soapinterop.org/" location="functional/float.wsdl" />
+    <import namespace="http://soapinterop.org/" location="functional/float.wsdl" />
+</definitions>
diff --git a/tests/fixtures/flattening/import-with-own-tags.wsdl b/tests/fixtures/flattening/import-with-own-tags.wsdl
new file mode 100644
index 0000000..20105cc
--- /dev/null
+++ b/tests/fixtures/flattening/import-with-own-tags.wsdl
@@ -0,0 +1,14 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    >
+    <import namespace="http://soapinterop.org/" location="functional/float.wsdl" />
+
+    <types>
+        <xsd:schema />
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/import.wsdl b/tests/fixtures/flattening/import.wsdl
new file mode 100644
index 0000000..4ab3e1a
--- /dev/null
+++ b/tests/fixtures/flattening/import.wsdl
@@ -0,0 +1,7 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/">
+    <import namespace="http://soapinterop.org/" location="functional/float.wsdl" />
+</definitions>
diff --git a/tests/fixtures/flattening/imported-include-nested.wsdl b/tests/fixtures/flattening/imported-include-nested.wsdl
new file mode 100644
index 0000000..f4ab712
--- /dev/null
+++ b/tests/fixtures/flattening/imported-include-nested.wsdl
@@ -0,0 +1,10 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+    <types>
+        <xsd:import schemaLocation="xsd/include.xsd" namespace="http://soapinterop.org/store1" />
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/importing-circular-xsd.wsdl b/tests/fixtures/flattening/importing-circular-xsd.wsdl
new file mode 100644
index 0000000..72156f5
--- /dev/null
+++ b/tests/fixtures/flattening/importing-circular-xsd.wsdl
@@ -0,0 +1,7 @@
+<?xml version="1.0"?>
+<definitions name="InteropTest"
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    xmlns="http://schemas.xmlsoap.org/wsdl/"
+    targetNamespace="http://soapinterop.org/">
+    <import namespace="http://soapinterop.org/" location="circular-xsd.wsdl" />
+</definitions>
diff --git a/tests/fixtures/flattening/include-namespaces.wsdl b/tests/fixtures/flattening/include-namespaces.wsdl
new file mode 100644
index 0000000..29c8188
--- /dev/null
+++ b/tests/fixtures/flattening/include-namespaces.wsdl
@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+    <types>
+        <xsd:schema targetNamespace="http://soapinterop.org/store1">
+            <xsd:include schemaLocation="xsd/additional-namespaces.xsd" />
+        </xsd:schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/include-nested.wsdl b/tests/fixtures/flattening/include-nested.wsdl
new file mode 100644
index 0000000..b0a9559
--- /dev/null
+++ b/tests/fixtures/flattening/include-nested.wsdl
@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+    <types>
+        <xsd:schema targetNamespace="http://soapinterop.org/store1">
+            <xsd:include schemaLocation="xsd/include.xsd" />
+        </xsd:schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/include.wsdl b/tests/fixtures/flattening/include.wsdl
new file mode 100644
index 0000000..97fe602
--- /dev/null
+++ b/tests/fixtures/flattening/include.wsdl
@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+    <types>
+        <xsd:schema targetNamespace="http://soapinterop.org/store1">
+            <xsd:include schemaLocation="xsd/store1.xsd" />
+        </xsd:schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/multi-import.wsdl b/tests/fixtures/flattening/multi-import.wsdl
new file mode 100644
index 0000000..9fc1f79
--- /dev/null
+++ b/tests/fixtures/flattening/multi-import.wsdl
@@ -0,0 +1,8 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/">
+    <import namespace="http://soapinterop.org/" location="functional/float.wsdl" />
+    <import namespace="http://soapinterop.org/" location="functional/empty-schema.wsdl" />
+</definitions>
diff --git a/tests/fixtures/flattening/multi-include.wsdl b/tests/fixtures/flattening/multi-include.wsdl
new file mode 100644
index 0000000..f3e5bf2
--- /dev/null
+++ b/tests/fixtures/flattening/multi-include.wsdl
@@ -0,0 +1,13 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+    <types>
+        <xsd:schema targetNamespace="http://soapinterop.org/store1">
+            <xsd:include schemaLocation="xsd/store1.xsd" />
+            <xsd:include schemaLocation="xsd/store1.xsd" />
+        </xsd:schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/multi-xsd.wsdl b/tests/fixtures/flattening/multi-xsd.wsdl
new file mode 100644
index 0000000..b887bc8
--- /dev/null
+++ b/tests/fixtures/flattening/multi-xsd.wsdl
@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<definitions name="InteropTest"
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    xmlns="http://schemas.xmlsoap.org/wsdl/"
+    targetNamespace="http://soapinterop.org/">
+    <types>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/xsd">
+            <xsd:import schemaLocation="xsd/store1.xsd" namespace="http://soapinterop.org/store1" />
+            <xsd:import schemaLocation="xsd/store2.xsd" namespace="http://soapinterop.org/store2" />
+        </schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/once-xsd.wsdl b/tests/fixtures/flattening/once-xsd.wsdl
new file mode 100644
index 0000000..6c2b132
--- /dev/null
+++ b/tests/fixtures/flattening/once-xsd.wsdl
@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<definitions name="InteropTest"
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    xmlns="http://schemas.xmlsoap.org/wsdl/"
+    targetNamespace="http://soapinterop.org/">
+    <types>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/xsd">
+            <xsd:import schemaLocation="xsd/store1.xsd" namespace="http://soapinterop.org/store1" />
+            <xsd:import schemaLocation="xsd/store1.xsd" namespace="http://soapinterop.org/store1" />
+        </schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/redefine-xsd.wsdl b/tests/fixtures/flattening/redefine-xsd.wsdl
new file mode 100644
index 0000000..5b4b3ab
--- /dev/null
+++ b/tests/fixtures/flattening/redefine-xsd.wsdl
@@ -0,0 +1,22 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+    <types>
+        <xsd:schema targetNamespace="http://soapinterop.org/store1">
+            <xsd:redefine schemaLocation="xsd/store1.xsd">
+                <xsd:complexType name="Store">
+                    <xsd:complexContent>
+                        <xsd:extension base="Store">
+                            <xsd:sequence>
+                                <xsd:element name="extra" minOccurs="0"/>
+                            </xsd:sequence>
+                        </xsd:extension>
+                    </xsd:complexContent>
+                </xsd:complexType>
+            </xsd:redefine>
+        </xsd:schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/result/circular-xsd-result.wsdl b/tests/fixtures/flattening/result/circular-xsd-result.wsdl
new file mode 100644
index 0000000..00fddab
--- /dev/null
+++ b/tests/fixtures/flattening/result/circular-xsd-result.wsdl
@@ -0,0 +1,18 @@
+<?xml version="1.0"?>
+<definitions name="InteropTest"
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    xmlns="http://schemas.xmlsoap.org/wsdl/"
+    targetNamespace="http://soapinterop.org/">
+    <types>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/xsd">
+            <xsd:import namespace="http://soapinterop.org/circular" />
+            <xsd:import namespace="http://soapinterop.org/circular-common" />
+        </schema>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/circular-common">
+            <xsd:import namespace="http://soapinterop.org/circular" />
+        </schema>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/circular">
+            <xsd:import namespace="http://soapinterop.org/circular-common" />
+        </schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/result/empty-typed.wsdl b/tests/fixtures/flattening/result/empty-typed.wsdl
new file mode 100644
index 0000000..b4250c4
--- /dev/null
+++ b/tests/fixtures/flattening/result/empty-typed.wsdl
@@ -0,0 +1,9 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+        xmlns:tns="http://soapinterop.org/"
+        xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        targetNamespace="http://soapinterop.org/">
+    <types />
+</definitions>
diff --git a/tests/fixtures/flattening/result/grouped-xsd-result.wsdl b/tests/fixtures/flattening/result/grouped-xsd-result.wsdl
new file mode 100644
index 0000000..64a6e54
--- /dev/null
+++ b/tests/fixtures/flattening/result/grouped-xsd-result.wsdl
@@ -0,0 +1,24 @@
+<?xml version="1.0"?>
+<definitions name="InteropTest"
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    xmlns="http://schemas.xmlsoap.org/wsdl/"
+    targetNamespace="http://soapinterop.org/">
+    <types>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/xsd">
+            <xsd:import namespace="http://soapinterop.org/store1" />
+            <xsd:import namespace="http://soapinterop.org/store1" />
+        </schema>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/store1">
+            <xsd:complexType name="Store">
+                <xsd:sequence>
+                    <element minOccurs="1" maxOccurs="1" name="Attribute1" type="string"/>
+                </xsd:sequence>
+            </xsd:complexType>
+            <xsd:complexType name="StoreInfo">
+                <xsd:sequence>
+                    <element minOccurs="1" maxOccurs="1" name="Attribute1" type="string"/>
+                </xsd:sequence>
+            </xsd:complexType>
+        </schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/result/import-with-own-tags-result.wsdl b/tests/fixtures/flattening/result/import-with-own-tags-result.wsdl
new file mode 100644
index 0000000..4b38fe4
--- /dev/null
+++ b/tests/fixtures/flattening/result/import-with-own-tags-result.wsdl
@@ -0,0 +1,49 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    >
+    <types>
+        <xsd:schema />
+    </types>
+
+    <message name="validateRequest">
+        <part name="input" type="xsd:float" />
+    </message>
+    <message name="validateResponse">
+        <part name="output" type="xsd:float" />
+    </message>
+
+    <portType name="InteropTestPortType">
+        <operation name="validate">
+            <input message="tns:validateRequest"/>
+            <output message="tns:validateResponse"/>
+        </operation>
+    </portType>
+
+    <binding name="InteropTestBinding" type="tns:InteropTestPortType">
+        <soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/>
+        <operation name="validate">
+            <soap:operation soapAction="http://soapinterop.org/validate" style="rpc"/>
+            <input>
+                <soap:body use="encoded" namespace="http://soapinterop.org/" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>
+            </input>
+            <output>
+                <soap:body use="encoded" namespace="http://soapinterop.org/" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>
+            </output>
+        </operation>
+    </binding>
+
+    <service name="InteropTest">
+        <port name="InteropTestPort" binding="tns:InteropTestBinding">
+            <soap:address location="http://soapinterop.org/"/>
+        </port>
+    </service>
+
+    <types>
+        <xsd:schema />
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/result/import-with-own-tags-single-type-result.wsdl b/tests/fixtures/flattening/result/import-with-own-tags-single-type-result.wsdl
new file mode 100644
index 0000000..401220d
--- /dev/null
+++ b/tests/fixtures/flattening/result/import-with-own-tags-single-type-result.wsdl
@@ -0,0 +1,46 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    >
+    <types>
+        <xsd:schema />
+        <xsd:schema />
+    </types>
+    <message name="validateRequest">
+        <part name="input" type="xsd:float" />
+    </message>
+    <message name="validateResponse">
+        <part name="output" type="xsd:float" />
+    </message>
+
+    <portType name="InteropTestPortType">
+        <operation name="validate">
+            <input message="tns:validateRequest"/>
+            <output message="tns:validateResponse"/>
+        </operation>
+    </portType>
+
+    <binding name="InteropTestBinding" type="tns:InteropTestPortType">
+        <soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/>
+        <operation name="validate">
+            <soap:operation soapAction="http://soapinterop.org/validate" style="rpc"/>
+            <input>
+                <soap:body use="encoded" namespace="http://soapinterop.org/" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>
+            </input>
+            <output>
+                <soap:body use="encoded" namespace="http://soapinterop.org/" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>
+            </output>
+        </operation>
+    </binding>
+
+    <service name="InteropTest">
+        <port name="InteropTestPort" binding="tns:InteropTestBinding">
+            <soap:address location="http://soapinterop.org/"/>
+        </port>
+    </service>
+
+</definitions>
diff --git a/tests/fixtures/flattening/result/importing-circular-xsd-result.wsdl b/tests/fixtures/flattening/result/importing-circular-xsd-result.wsdl
new file mode 100644
index 0000000..00fddab
--- /dev/null
+++ b/tests/fixtures/flattening/result/importing-circular-xsd-result.wsdl
@@ -0,0 +1,18 @@
+<?xml version="1.0"?>
+<definitions name="InteropTest"
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    xmlns="http://schemas.xmlsoap.org/wsdl/"
+    targetNamespace="http://soapinterop.org/">
+    <types>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/xsd">
+            <xsd:import namespace="http://soapinterop.org/circular" />
+            <xsd:import namespace="http://soapinterop.org/circular-common" />
+        </schema>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/circular-common">
+            <xsd:import namespace="http://soapinterop.org/circular" />
+        </schema>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/circular">
+            <xsd:import namespace="http://soapinterop.org/circular-common" />
+        </schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/result/include-namespaces.wsdl b/tests/fixtures/flattening/result/include-namespaces.wsdl
new file mode 100644
index 0000000..7d3cc20
--- /dev/null
+++ b/tests/fixtures/flattening/result/include-namespaces.wsdl
@@ -0,0 +1,18 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+    <types>
+        <xsd:schema targetNamespace="http://soapinterop.org/store1"
+                    xmlns:foo="http://foo"
+                    xmlns:bar="http://bar">
+            <xsd:complexType name="Store">
+                <xsd:sequence>
+                    <xsd:element minOccurs="1" maxOccurs="1" name="Attribute1" type="string"/>
+                </xsd:sequence>
+            </xsd:complexType>
+        </xsd:schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/result/include.wsdl b/tests/fixtures/flattening/result/include.wsdl
new file mode 100644
index 0000000..df3c73f
--- /dev/null
+++ b/tests/fixtures/flattening/result/include.wsdl
@@ -0,0 +1,16 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+    <types>
+        <xsd:schema targetNamespace="http://soapinterop.org/store1">
+            <xsd:complexType name="Store">
+                <xsd:sequence>
+                    <xsd:element minOccurs="1" maxOccurs="1" name="Attribute1" type="string"/>
+                </xsd:sequence>
+            </xsd:complexType>
+        </xsd:schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/result/multi-import-result.wsdl b/tests/fixtures/flattening/result/multi-import-result.wsdl
new file mode 100644
index 0000000..4b38fe4
--- /dev/null
+++ b/tests/fixtures/flattening/result/multi-import-result.wsdl
@@ -0,0 +1,49 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    >
+    <types>
+        <xsd:schema />
+    </types>
+
+    <message name="validateRequest">
+        <part name="input" type="xsd:float" />
+    </message>
+    <message name="validateResponse">
+        <part name="output" type="xsd:float" />
+    </message>
+
+    <portType name="InteropTestPortType">
+        <operation name="validate">
+            <input message="tns:validateRequest"/>
+            <output message="tns:validateResponse"/>
+        </operation>
+    </portType>
+
+    <binding name="InteropTestBinding" type="tns:InteropTestPortType">
+        <soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/>
+        <operation name="validate">
+            <soap:operation soapAction="http://soapinterop.org/validate" style="rpc"/>
+            <input>
+                <soap:body use="encoded" namespace="http://soapinterop.org/" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>
+            </input>
+            <output>
+                <soap:body use="encoded" namespace="http://soapinterop.org/" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>
+            </output>
+        </operation>
+    </binding>
+
+    <service name="InteropTest">
+        <port name="InteropTestPort" binding="tns:InteropTestBinding">
+            <soap:address location="http://soapinterop.org/"/>
+        </port>
+    </service>
+
+    <types>
+        <xsd:schema />
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/result/multi-include.wsdl b/tests/fixtures/flattening/result/multi-include.wsdl
new file mode 100644
index 0000000..df3c73f
--- /dev/null
+++ b/tests/fixtures/flattening/result/multi-include.wsdl
@@ -0,0 +1,16 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+    <types>
+        <xsd:schema targetNamespace="http://soapinterop.org/store1">
+            <xsd:complexType name="Store">
+                <xsd:sequence>
+                    <xsd:element minOccurs="1" maxOccurs="1" name="Attribute1" type="string"/>
+                </xsd:sequence>
+            </xsd:complexType>
+        </xsd:schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/result/multi-xsd-result.wsdl b/tests/fixtures/flattening/result/multi-xsd-result.wsdl
new file mode 100644
index 0000000..14322b6
--- /dev/null
+++ b/tests/fixtures/flattening/result/multi-xsd-result.wsdl
@@ -0,0 +1,26 @@
+<?xml version="1.0"?>
+<definitions name="InteropTest"
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    xmlns="http://schemas.xmlsoap.org/wsdl/"
+    targetNamespace="http://soapinterop.org/">
+    <types>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/xsd">
+            <xsd:import namespace="http://soapinterop.org/store1" />
+            <xsd:import namespace="http://soapinterop.org/store2" />
+        </schema>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/store1">
+            <xsd:complexType name="Store">
+                <xsd:sequence>
+                    <element minOccurs="1" maxOccurs="1" name="Attribute1" type="string"/>
+                </xsd:sequence>
+            </xsd:complexType>
+        </schema>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/store2">
+            <xsd:complexType name="Store">
+                <xsd:sequence>
+                    <element minOccurs="1" maxOccurs="1" name="Attribute2" type="string"/>
+                </xsd:sequence>
+            </xsd:complexType>
+        </schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/result/once-xsd-result.wsdl b/tests/fixtures/flattening/result/once-xsd-result.wsdl
new file mode 100644
index 0000000..bc7860c
--- /dev/null
+++ b/tests/fixtures/flattening/result/once-xsd-result.wsdl
@@ -0,0 +1,19 @@
+<?xml version="1.0"?>
+<definitions name="InteropTest"
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    xmlns="http://schemas.xmlsoap.org/wsdl/"
+    targetNamespace="http://soapinterop.org/">
+    <types>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/xsd">
+            <xsd:import namespace="http://soapinterop.org/store1" />
+            <xsd:import namespace="http://soapinterop.org/store1" />
+        </schema>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/store1">
+            <xsd:complexType name="Store">
+                <xsd:sequence>
+                    <element minOccurs="1" maxOccurs="1" name="Attribute1" type="string"/>
+                </xsd:sequence>
+            </xsd:complexType>
+        </schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/result/redefine-xsd-result.wsdl b/tests/fixtures/flattening/result/redefine-xsd-result.wsdl
new file mode 100644
index 0000000..088279d
--- /dev/null
+++ b/tests/fixtures/flattening/result/redefine-xsd-result.wsdl
@@ -0,0 +1,25 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+    <types>
+        <xsd:schema targetNamespace="http://soapinterop.org/store1">
+            <xsd:complexType name="Store">
+                <xsd:sequence>
+                    <xsd:element minOccurs="1" maxOccurs="1" name="Attribute1" type="string"/>
+                </xsd:sequence>
+            </xsd:complexType>
+            <xsd:complexType name="Store">
+                <xsd:complexContent>
+                    <xsd:extension base="Store">
+                        <xsd:sequence>
+                            <xsd:element name="extra" minOccurs="0"/>
+                        </xsd:sequence>
+                    </xsd:extension>
+                </xsd:complexContent>
+            </xsd:complexType>
+        </xsd:schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/result/single-xsd-result.wsdl b/tests/fixtures/flattening/result/single-xsd-result.wsdl
new file mode 100644
index 0000000..f037567
--- /dev/null
+++ b/tests/fixtures/flattening/result/single-xsd-result.wsdl
@@ -0,0 +1,18 @@
+<?xml version="1.0"?>
+<definitions name="InteropTest"
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    xmlns="http://schemas.xmlsoap.org/wsdl/"
+    targetNamespace="http://soapinterop.org/">
+    <types>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/xsd">
+            <xsd:import namespace="http://soapinterop.org/store1" />
+        </schema>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/store1">
+            <xsd:complexType name="Store">
+                <xsd:sequence>
+                    <element minOccurs="1" maxOccurs="1" name="Attribute1" type="string"/>
+                </xsd:sequence>
+            </xsd:complexType>
+        </schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/result/tnsless-xsd-result.wsdl b/tests/fixtures/flattening/result/tnsless-xsd-result.wsdl
new file mode 100644
index 0000000..d607663
--- /dev/null
+++ b/tests/fixtures/flattening/result/tnsless-xsd-result.wsdl
@@ -0,0 +1,19 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+    <types>
+        <xsd:schema targetNamespace="http://soapinterop.org/store1">
+            
+        </xsd:schema>
+        <xsd:schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+            <xsd:complexType name="Store">
+                <xsd:sequence>
+                    <element minOccurs="1" maxOccurs="1" name="Attribute1" type="string"/>
+                </xsd:sequence>
+            </xsd:complexType>
+        </xsd:schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/single-xsd.wsdl b/tests/fixtures/flattening/single-xsd.wsdl
new file mode 100644
index 0000000..83fa3ec
--- /dev/null
+++ b/tests/fixtures/flattening/single-xsd.wsdl
@@ -0,0 +1,11 @@
+<?xml version="1.0"?>
+<definitions name="InteropTest"
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    xmlns="http://schemas.xmlsoap.org/wsdl/"
+    targetNamespace="http://soapinterop.org/">
+    <types>
+        <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/xsd">
+            <xsd:import schemaLocation="xsd/store1.xsd" namespace="http://soapinterop.org/store1" />
+        </schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/tnsless-xsd.wsdl b/tests/fixtures/flattening/tnsless-xsd.wsdl
new file mode 100644
index 0000000..855ac06
--- /dev/null
+++ b/tests/fixtures/flattening/tnsless-xsd.wsdl
@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<definitions
+        xmlns="http://schemas.xmlsoap.org/wsdl/"
+        xmlns:tns="http://soapinterop.org/"
+        targetNamespace="http://soapinterop.org/"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+    <types>
+        <xsd:schema targetNamespace="http://soapinterop.org/store1">
+            <xsd:include schemaLocation="xsd/tnsless.xsd" />
+        </xsd:schema>
+    </types>
+</definitions>
diff --git a/tests/fixtures/flattening/xsd/additional-namespaces.xsd b/tests/fixtures/flattening/xsd/additional-namespaces.xsd
new file mode 100644
index 0000000..747f5b6
--- /dev/null
+++ b/tests/fixtures/flattening/xsd/additional-namespaces.xsd
@@ -0,0 +1,12 @@
+<schema xmlns="http://www.w3.org/2001/XMLSchema"
+        xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+        targetNamespace="http://soapinterop.org/store1"
+        xmlns:foo="http://foo"
+        xmlns:bar="http://bar"
+>
+    <xsd:complexType name="Store">
+        <xsd:sequence>
+            <element minOccurs="1" maxOccurs="1" name="Attribute1" type="string"/>
+        </xsd:sequence>
+    </xsd:complexType>
+</schema>
\ No newline at end of file
diff --git a/tests/fixtures/flattening/xsd/circular-common.xsd b/tests/fixtures/flattening/xsd/circular-common.xsd
new file mode 100644
index 0000000..46ecb22
--- /dev/null
+++ b/tests/fixtures/flattening/xsd/circular-common.xsd
@@ -0,0 +1,3 @@
+<schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/circular-common">
+    <xsd:import schemaLocation="circular.xsd" namespace="http://soapinterop.org/circular" />
+</schema>
\ No newline at end of file
diff --git a/tests/fixtures/flattening/xsd/circular.xsd b/tests/fixtures/flattening/xsd/circular.xsd
new file mode 100644
index 0000000..ff07211
--- /dev/null
+++ b/tests/fixtures/flattening/xsd/circular.xsd
@@ -0,0 +1,3 @@
+<schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/circular">
+    <xsd:import schemaLocation="circular-common.xsd" namespace="http://soapinterop.org/circular-common" />
+</schema>
\ No newline at end of file
diff --git a/tests/fixtures/flattening/xsd/include.xsd b/tests/fixtures/flattening/xsd/include.xsd
new file mode 100644
index 0000000..8cadb95
--- /dev/null
+++ b/tests/fixtures/flattening/xsd/include.xsd
@@ -0,0 +1,3 @@
+<schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/store1">
+    <xsd:include schemaLocation="./store1.xsd" />
+</schema>
\ No newline at end of file
diff --git a/tests/fixtures/flattening/xsd/store1-extras.xsd b/tests/fixtures/flattening/xsd/store1-extras.xsd
new file mode 100644
index 0000000..490be3c
--- /dev/null
+++ b/tests/fixtures/flattening/xsd/store1-extras.xsd
@@ -0,0 +1,7 @@
+<schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/store1">
+    <xsd:complexType name="StoreInfo">
+        <xsd:sequence>
+            <element minOccurs="1" maxOccurs="1" name="Attribute1" type="string"/>
+        </xsd:sequence>
+    </xsd:complexType>
+</schema>
\ No newline at end of file
diff --git a/tests/fixtures/flattening/xsd/store1.xsd b/tests/fixtures/flattening/xsd/store1.xsd
new file mode 100644
index 0000000..247bfe1
--- /dev/null
+++ b/tests/fixtures/flattening/xsd/store1.xsd
@@ -0,0 +1,7 @@
+<schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/store1">
+    <xsd:complexType name="Store">
+        <xsd:sequence>
+            <element minOccurs="1" maxOccurs="1" name="Attribute1" type="string"/>
+        </xsd:sequence>
+    </xsd:complexType>
+</schema>
\ No newline at end of file
diff --git a/tests/fixtures/flattening/xsd/store2.xsd b/tests/fixtures/flattening/xsd/store2.xsd
new file mode 100644
index 0000000..61213e7
--- /dev/null
+++ b/tests/fixtures/flattening/xsd/store2.xsd
@@ -0,0 +1,7 @@
+<schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://soapinterop.org/store2">
+    <xsd:complexType name="Store">
+        <xsd:sequence>
+            <element minOccurs="1" maxOccurs="1" name="Attribute2" type="string"/>
+        </xsd:sequence>
+    </xsd:complexType>
+</schema>
\ No newline at end of file
diff --git a/tests/fixtures/flattening/xsd/tnsless.xsd b/tests/fixtures/flattening/xsd/tnsless.xsd
new file mode 100644
index 0000000..6c77960
--- /dev/null
+++ b/tests/fixtures/flattening/xsd/tnsless.xsd
@@ -0,0 +1,7 @@
+<schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+    <xsd:complexType name="Store">
+        <xsd:sequence>
+            <element minOccurs="1" maxOccurs="1" name="Attribute1" type="string"/>
+        </xsd:sequence>
+    </xsd:complexType>
+</schema>
\ No newline at end of file
diff --git a/tools/psalm.phar b/tools/psalm.phar
index 0452e69..2d61da6 100755
Binary files a/tools/psalm.phar and b/tools/psalm.phar differ