Unify 'print' and 'printSchema' output for block strings

src/language/__tests__/blockString-test.js

@@ -0,0 +1,148 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict
+ */
+
+import { expect } from 'chai';
+import { describe, it } from 'mocha';
+import { dedentBlockStringValue, printBlockString } from '../blockString';
+
+function joinLines(...args) {
+  return args.join('\n');
+}
+
+describe('dedentBlockStringValue', () => {
+  it('removes uniform indentation from a string', () => {
+    const rawValue = joinLines(
+      '',
+      '    Hello,',
+      '      World!',
+      '',
+      '    Yours,',
+      '      GraphQL.',
+    );
+    expect(dedentBlockStringValue(rawValue)).to.equal(
+      joinLines('Hello,', '  World!', '', 'Yours,', '  GraphQL.'),
+    );
+  });
+
+  it('removes empty leading and trailing lines', () => {
+    const rawValue = joinLines(
+      '',
+      '',
+      '    Hello,',
+      '      World!',
+      '',
+      '    Yours,',
+      '      GraphQL.',
+      '',
+      '',
+    );
+    expect(dedentBlockStringValue(rawValue)).to.equal(
+      joinLines('Hello,', '  World!', '', 'Yours,', '  GraphQL.'),
+    );
+  });
+
+  it('removes blank leading and trailing lines', () => {
+    const rawValue = joinLines(
+      '  ',
+      '        ',
+      '    Hello,',
+      '      World!',
+      '',
+      '    Yours,',
+      '      GraphQL.',
+      '        ',
+      '  ',
+    );
+    expect(dedentBlockStringValue(rawValue)).to.equal(
+      joinLines('Hello,', '  World!', '', 'Yours,', '  GraphQL.'),
+    );
+  });
+
+  it('retains indentation from first line', () => {
+    const rawValue = joinLines(
+      '    Hello,',
+      '      World!',
+      '',
+      '    Yours,',
+      '      GraphQL.',
+    );
+    expect(dedentBlockStringValue(rawValue)).to.equal(
+      joinLines('    Hello,', '  World!', '', 'Yours,', '  GraphQL.'),
+    );
+  });
+
+  it('does not alter trailing spaces', () => {
+    const rawValue = joinLines(
+      '               ',
+      '    Hello,     ',
+      '      World!   ',
+      '               ',
+      '    Yours,     ',
+      '      GraphQL. ',
+      '               ',
+    );
+    expect(dedentBlockStringValue(rawValue)).to.equal(
+      joinLines(
+        'Hello,     ',
+        '  World!   ',
+        '           ',
+        'Yours,     ',
+        '  GraphQL. ',
+      ),
+    );
+  });
+});
+
+describe('printBlockString', () => {
+  it('by default print block strings as single line', () => {
+    const str = 'one liner';
+    expect(printBlockString(str)).to.equal('"""one liner"""');
+    expect(printBlockString(str, '', true)).to.equal('"""\none liner\n"""');
+  });
+
+  it('correctly prints single-line with leading space', () => {
+    const str = '    space-led string';
+    expect(printBlockString(str)).to.equal('"""    space-led string"""');
+    expect(printBlockString(str, '', true)).to.equal(
+      '"""    space-led string\n"""',
+    );
+  });
+
+  it('correctly prints single-line with leading space and quotation', () => {
+    const str = '    space-led value "quoted string"';
+
+    expect(printBlockString(str)).to.equal(
+      '"""    space-led value "quoted string"\n"""',
+    );
+
+    expect(printBlockString(str, '', true)).to.equal(
+      '"""    space-led value "quoted string"\n"""',
+    );
+  });
+
+  it('correctly prints string with a first line indentation', () => {
+    const str = joinLines(
+      '    first  ',
+      '  line     ',
+      'indentation',
+      '     string',
+    );
+
+    expect(printBlockString(str)).to.equal(
+      joinLines(
+        '"""',
+        '    first  ',
+        '  line     ',
+        'indentation',
+        '     string',
+        '"""',
+      ),
+    );
+  });
+});

src/language/__tests__/printer-test.js

@@ -98,55 +98,6 @@ describe('Printer: Query document', () => {
     `);
   });
 
-  describe('block string', () => {
-    it('correctly prints single-line with leading space', () => {
-      const mutationASTWithArtifacts = parse(
-        '{ field(arg: """    space-led value""") }',
-      );
-      expect(print(mutationASTWithArtifacts)).to.equal(dedent`
-        {
-          field(arg: """    space-led value""")
-        }
-      `);
-    });
-
-    it('correctly prints string with a first line indentation', () => {
-      const mutationASTWithArtifacts = parse(`
-        {
-          field(arg: """
-                first
-              line
-            indentation
-          """)
-        }
-      `);
-      expect(print(mutationASTWithArtifacts)).to.equal(dedent`
-        {
-          field(arg: """
-                first
-              line
-            indentation
-          """)
-        }
-      `);
-    });
-
-    it('correctly prints single-line with leading space and quotation', () => {
-      const mutationASTWithArtifacts = parse(`
-        {
-          field(arg: """    space-led value "quoted string"
-          """)
-        }
-      `);
-      expect(print(mutationASTWithArtifacts)).to.equal(dedent`
-        {
-          field(arg: """    space-led value "quoted string"
-          """)
-        }
-      `);
-    });
-  });
-
   it('Experimental: correctly prints fragment defined variables', () => {
     const fragmentWithVariable = parse(
       `

src/language/__tests__/schema-printer-test.js

@@ -54,18 +54,12 @@ describe('Printer: SDL document', () => {
       type Foo implements Bar & Baz {
         "Description of the \`one\` field."
         one: Type
-        """
-        This is a description of the \`two\` field.
-        """
+        """This is a description of the \`two\` field."""
         two(
-          """
-          This is a description of the \`argument\` argument.
-          """
+          """This is a description of the \`argument\` argument."""
           argument: InputType!
         ): Type
-        """
-        This is a description of the \`three\` field.
-        """
+        """This is a description of the \`three\` field."""
         three(argument: InputType, other: String): Int
         four(argument: String = "string"): String
         five(argument: [String] = ["string", "string"]): String
@@ -121,13 +115,9 @@ describe('Printer: SDL document', () => {
       extend scalar CustomScalar @onScalar
 
       enum Site {
-        """
-        This is a description of the \`DESKTOP\` value
-        """
+        """This is a description of the \`DESKTOP\` value"""
         DESKTOP
-        """
-        This is a description of the \`MOBILE\` value
-        """
+        """This is a description of the \`MOBILE\` value"""
         MOBILE
         "This is a description of the \`WEB\` value"
         WEB
@@ -163,9 +153,7 @@ describe('Printer: SDL document', () => {
 
       extend input InputType @onInputObject
 
-      """
-      This is a description of the \`@skip\` directive
-      """
+      """This is a description of the \`@skip\` directive"""
       directive @skip(if: Boolean! @onArgumentDefinition) on FIELD | FRAGMENT_SPREAD | INLINE_FRAGMENT
 
       directive @include(if: Boolean!) on FIELD | FRAGMENT_SPREAD | INLINE_FRAGMENT

src/language/blockStringValue.js → src/language/blockString.js

@@ -13,7 +13,7 @@
  *
  * This implements the GraphQL spec's BlockStringValue() static algorithm.
  */
-export default function blockStringValue(rawString: string): string {
+export function dedentBlockStringValue(rawString: string): string {
   // Expand a block string's raw value into independent lines.
   const lines = rawString.split(/\r\n|[\n\r]/g);
 
@@ -62,3 +62,32 @@ function leadingWhitespace(str) {
 function isBlank(str) {
   return leadingWhitespace(str) === str.length;
 }
+
+/**
+ * Print a block string in the indented block form by adding a leading and
+ * trailing blank line. However, if a block string starts with whitespace and is
+ * a single-line, adding a leading blank line would strip that whitespace.
+ */
+export function printBlockString(
+  value: string,
+  indentation?: string = '',
+  preferMultipleLines?: ?boolean = false,
+): string {
+  const isSingleLine = value.indexOf('\n') === -1;
+  const hasLeadingSpace = value[0] === ' ' || value[0] === '\t';
+  const hasTrailingQuote = value[value.length - 1] === '"';
+  const printAsMultipleLines =
+    !isSingleLine || hasTrailingQuote || preferMultipleLines;
+
+  let result = '';
+  // Format a multi-line block quote to account for leading space.
+  if (printAsMultipleLines && !(isSingleLine && hasLeadingSpace)) {
+    result += '\n' + indentation;
+  }
+  result += indentation ? value.replace(/\n/g, '\n' + indentation) : value;
+  if (printAsMultipleLines) {
+    result += '\n';
+  }
+
+  return '"""' + result.replace(/"""/g, '\\"""') + '"""';
+}