[release-2.x] fix converting introspection to SDL (#4316)

* fix converting introspection to SDL

* add a flag that keeps the old behaviour in places where we might still need it

Author: martinbonnin

apollo-compiler/src/main/kotlin/com/apollographql/apollo/compiler/parser/introspection/introspection2sdl.kt

@@ -5,13 +5,24 @@ import okio.buffer
 import okio.sink
 import java.io.File
 
-fun IntrospectionSchema.toSDL(file: File) {
+/**
+ * Previous versions of this method used to encode defaultValues as Json elements. For an example:
+ * "defaultValue": [0, 1]
+ *
+ * This is wrong. The spec mandates defaultValue to be GraphQL encoded String:
+ * "defaultValue": "[0, 1]"
+ *
+ * For backward compatibility, use [legacyDefaultValues] = true
+ */
+fun IntrospectionSchema.toSDL(file: File, legacyDefaultValues: Boolean) {
   file.sink().buffer().use {
-    toSDL(it)
+    toSDL(it, legacyDefaultValues)
   }
 }
 
-fun IntrospectionSchema.toSDL(sink: BufferedSink) {
+fun IntrospectionSchema.toSDL(file: File) = toSDL(file, true)
+
+fun IntrospectionSchema.toSDL(sink: BufferedSink, legacyDefaultValues: Boolean) {
   val builtinsTypes = setOf(
       "Int", "Float", "String", "Boolean", "ID",
       "__Directive", "__DirectiveLocation", "__EnumValue", "__Field", "__InputValue", "__Schema", "__Type", "__TypeKind"
@@ -25,9 +36,9 @@ fun IntrospectionSchema.toSDL(sink: BufferedSink) {
     when (it) {
       is IntrospectionSchema.Type.Scalar -> it.toSDL(sink)
       is IntrospectionSchema.Type.Enum -> it.toSDL(sink)
-      is IntrospectionSchema.Type.InputObject -> it.toSDL(sink)
-      is IntrospectionSchema.Type.Interface -> it.toSDL(sink)
-      is IntrospectionSchema.Type.Object -> it.toSDL(sink, allInterfaces)
+      is IntrospectionSchema.Type.InputObject -> it.toSDL(sink, legacyDefaultValues)
+      is IntrospectionSchema.Type.Interface -> it.toSDL(sink, legacyDefaultValues)
+      is IntrospectionSchema.Type.Object -> it.toSDL(sink, allInterfaces, legacyDefaultValues)
       is IntrospectionSchema.Type.Union -> it.toSDL(sink)
     }
     // Add a newline as a separation
@@ -40,6 +51,8 @@ fun IntrospectionSchema.toSDL(sink: BufferedSink) {
   sink.writeUtf8("}\n")
 }
 
+fun IntrospectionSchema.toSDL(sink: BufferedSink) = toSDL(sink, true)
+
 private fun BufferedSink.writeDescription(description: String?, indent: String = "") {
   if (!description.isNullOrBlank()) {
     writeUtf8(
@@ -86,11 +99,11 @@ private fun IntrospectionSchema.Type.Enum.Value.toSDL(sink: BufferedSink) {
   sink.writeDeprecatedDirective(isDeprecated, deprecationReason)
 }
 
-private fun IntrospectionSchema.Type.InputObject.toSDL(sink: BufferedSink) {
+private fun IntrospectionSchema.Type.InputObject.toSDL(sink: BufferedSink, legacyDefaultValues: Boolean) {
   sink.writeDescription(description)
   sink.writeUtf8("input $name {\n")
   inputFields.forEach {
-    it.toSDL(sink)
+    it.toSDL(sink, legacyDefaultValues)
     sink.writeUtf8("\n")
   }
   sink.writeUtf8("}\n")
@@ -132,33 +145,40 @@ private fun BufferedSink.writeValue(value: Any?) {
   }
 }
 
-private fun IntrospectionSchema.InputField.toSDL(sink: BufferedSink) {
+private fun IntrospectionSchema.InputField.toSDL(sink: BufferedSink, legacyDefaultValues: Boolean) {
   sink.writeDescription(description, "  ")
   sink.writeUtf8("  $name: ${type.asGraphQLType()}")
   if (defaultValue != null) {
     sink.writeUtf8(" = ")
-    sink.writeValue(defaultValue)
+    if (!legacyDefaultValues && defaultValue is String) {
+      // defaultValue is already encoded as GraphQL, we can pass it verbatim
+      sink.writeUtf8(defaultValue)
+    } else {
+      // legacy mode if we bump into an introspection schema that doesn't encode the default value
+      sink.writeValue(defaultValue)
+    }
+
   }
   sink.writeDeprecatedDirective(isDeprecated, deprecationReason)
 }
 
-private fun IntrospectionSchema.Type.Interface.toSDL(sink: BufferedSink) {
+private fun IntrospectionSchema.Type.Interface.toSDL(sink: BufferedSink, legacyDefaultValue: Boolean) {
   sink.writeDescription(description)
   sink.writeUtf8("interface $name {\n")
   fields?.forEach {
-    it.toSDL(sink)
+    it.toSDL(sink, legacyDefaultValue)
     sink.writeUtf8("\n")
   }
   sink.writeUtf8("}\n")
 }
 
-private fun IntrospectionSchema.Field.toSDL(sink: BufferedSink) {
+private fun IntrospectionSchema.Field.toSDL(sink: BufferedSink, legacyDefaultValue: Boolean) {
   sink.writeDescription(description, "  ")
   sink.writeUtf8("  $name")
   if (args.isNotEmpty()) {
     sink.writeUtf8("(")
     args.forEachIndexed { index, arg ->
-      arg.toSDL(sink)
+      arg.toSDL(sink, legacyDefaultValue)
       if (index != args.size - 1) {
         sink.writeUtf8(", ")
       }
@@ -169,20 +189,26 @@ private fun IntrospectionSchema.Field.toSDL(sink: BufferedSink) {
   sink.writeDeprecatedDirective(isDeprecated, deprecationReason)
 }
 
-private fun IntrospectionSchema.Field.Argument.toSDL(sink: BufferedSink) {
+private fun IntrospectionSchema.Field.Argument.toSDL(sink: BufferedSink, legacyDefaultValue: Boolean) {
   if (!description.isNullOrBlank()) {
     // Write the description inline
     sink.writeUtf8("\"\"\"$description\"\"\" ")
   }
   sink.writeUtf8("$name: ${type.asGraphQLType()}")
   if (defaultValue != null) {
     sink.writeUtf8(" = ")
-    sink.writeValue(defaultValue)
+    if (!legacyDefaultValue && defaultValue is String) {
+      // defaultValue is already encoded as GraphQL, we can pass it verbatim
+      sink.writeUtf8(defaultValue)
+    } else {
+      // legacy mode if we bump into an introspection schema that doesn't encode the default value
+      sink.writeValue(defaultValue)
+    }
   }
   sink.writeDeprecatedDirective(isDeprecated, deprecationReason)
 }
 
-private fun IntrospectionSchema.Type.Object.toSDL(sink: BufferedSink, interfaces: List<IntrospectionSchema.Type.Interface>) {
+private fun IntrospectionSchema.Type.Object.toSDL(sink: BufferedSink, interfaces: List<IntrospectionSchema.Type.Interface>, legacyDefaultValue: Boolean) {
   sink.writeDescription(description, "")
   sink.writeUtf8("type $name")
   val implements = interfaces.filter {
@@ -203,7 +229,7 @@ private fun IntrospectionSchema.Type.Object.toSDL(sink: BufferedSink, interfaces
   sink.writeUtf8(" {\n")
 
   fields?.forEach {
-    it.toSDL(sink)
+    it.toSDL(sink, legacyDefaultValue)
     sink.writeUtf8("\n")
   }
 

apollo-compiler/src/test/kotlin/com/apollographql/apollo/compiler/GraphSdlParseTest.kt

@@ -6,7 +6,6 @@ import com.apollographql.apollo.compiler.parser.introspection.IntrospectionSchem
 import com.apollographql.apollo.compiler.parser.introspection.toSDL
 import com.apollographql.apollo.compiler.parser.sdl.GraphSdlSchema
 import com.apollographql.apollo.compiler.parser.sdl.toIntrospectionSchema
-import com.google.common.truth.Truth
 import com.google.common.truth.Truth.assertThat
 import org.junit.Assert.assertEquals
 import org.junit.Assert.fail
@@ -84,6 +83,17 @@ class GraphSdlParseTest() {
     assertEquals(initialSchema, finalSchema)
   }
 
+  @Test
+  fun `defaultValues are correctly written`() {
+    val initialSchema = IntrospectionSchema(File("src/test/sdl/default-values.json")).normalize()
+    val sdlFile = File("build/sdl-test/schema.sdl")
+    sdlFile.parentFile.deleteRecursively()
+    sdlFile.parentFile.mkdirs()
+    initialSchema.toSDL(sdlFile, legacyDefaultValues = false)
+
+    assertEquals(File("src/test/sdl/default-values.sdl").readText(), sdlFile.readText())
+  }
+
   /**
    * use to make easier diffs
    */