[jest-docblock] add docblock.print()

packages/jest-docblock/README.md

@@ -30,6 +30,7 @@ Pragmas can also take arguments:
 `jest-docblock` can:
 * extract the docblock from some code as a string
 * parse a docblock string's pragmas into an object
+* print an object and some comments back to a string
 
 ## Installation
 ```sh
@@ -56,13 +57,15 @@ const code = `
  }
 `;
 
-const { extract, parse } = require("jest-docblock");
+const { extract, parse, print } = require("jest-docblock");
 
 const docblock = extract(code);
 console.log(docblock); // "/**\n * Everything is awesome!\n * \n * @everything is:awesome\n * @flow\n */"
 
 const pragmas = parse(docblock);
 console.log(pragmas); // { everything: "is:awesome", flow: "" }
+
+console.log(print(pragmas), "hi!") // /**\n * hi!\n *\n * @everything is:awesome\n * @flow\n */;
 ```
 
 ## API Documentation
@@ -72,3 +75,6 @@ Extracts a docblock from some file contents. Returns the docblock contained in `
 
 ### `parse(docblock: string): {[key: string]: string}`
 Parses the pragmas in a docblock string into an object whose keys are the pragma tags and whose values are the arguments to those pragmas.
+
+### `print(object: {[key: string]: string}, comments?: string): string`
+Prints an object of key-value pairs back into a docblock. If `comments` are provided, they will be positioned on the top of the docblock.

packages/jest-docblock/src/__tests__/index.test.js

@@ -213,4 +213,80 @@ describe('docblock', () => {
       providesModule: 'apple/banana',
     });
   });
+
+  it('prints docblocks with no keys as empty string', () => {
+    const object = {};
+    expect(docblock.print(object)).toEqual('');
+  });
+
+  it('prints docblocks with one key on one line', () => {
+    const object = {flow: ''};
+    expect(docblock.print(object)).toEqual('/** @flow */');
+  });
+
+  it('prints docblocks with multiple keys on multiple lines', () => {
+    const object = {
+      flow: '',
+      format: '',
+    };
+    expect(docblock.print(object)).toEqual(
+      '/**' + os.EOL + ' * @flow' + os.EOL + ' * @format' + os.EOL + ' */',
+    );
+  });
+
+  it('prints docblocks with values', () => {
+    const object = {
+      flow: 'foo',
+      providesModule: 'x/y/z',
+    };
+    expect(docblock.print(object)).toEqual(
+      '/**' +
+        os.EOL +
+        ' * @flow foo' +
+        os.EOL +
+        ' * @providesModule x/y/z' +
+        os.EOL +
+        ' */',
+    );
+  });
+
+  it('prints docblocks with comments', () => {
+    const object = {flow: 'foo'};
+    const comments = 'hello';
+    expect(docblock.print(object, comments)).toEqual(
+      '/**' +
+        os.EOL +
+        ' * hello' +
+        os.EOL +
+        ' *' +
+        os.EOL +
+        ' * @flow foo' +
+        os.EOL +
+        ' */',
+    );
+  });
+
+  it('prints docblocks with comments and no keys', () => {
+    const object = {};
+    const comments = 'Copyright 2004-present Facebook. All Rights Reserved.';
+    expect(docblock.print(object, comments)).toEqual(
+      '/**' + os.EOL + ' * ' + comments + os.EOL + ' */',
+    );
+  });
+
+  it('prints docblocks with multiline comments', () => {
+    const object = {};
+    const comments = 'hello' + os.EOL + 'world';
+    expect(docblock.print(object, comments)).toEqual(
+      '/**' + os.EOL + ' * hello' + os.EOL + ' * world' + os.EOL + ' */',
+    );
+  });
+
+  it('prints docblocks that are parseable', () => {
+    const object = {a: 'b', c: ''};
+    const comments = 'hello world!';
+    const formatted = docblock.print(object, comments);
+    const parsed = docblock.parse(formatted);
+    expect(parsed).toEqual(object);
+  });
 });

packages/jest-docblock/src/index.js

@@ -8,6 +8,8 @@
  * @flow
  */
 
+const os = require('os');
+
 const commentEndRe = /\*\/$/;
 const commentStartRe = /^\/\*\*/;
 const docblockRe = /^\s*(\/\*\*?(.|\r?\n)*?\*\/)/;
@@ -47,5 +49,50 @@ function parse(docblock: string): {[key: string]: string} {
   return result;
 }
 
+function print(
+  object: {[key: string]: string} = {},
+  comments: string = '',
+): string {
+  const head = '/**';
+  const start = ' *';
+  const tail = ' */';
+
+  const keys = Object.keys(object);
+  const line = os.EOL;
+
+  const printedObject = keys
+    .map(key => start + ' ' + printKeyValue(key, object[key]) + line)
+    .join('');
+
+  if (!comments) {
+    if (keys.length === 0) {
+      return '';
+    }
+    if (keys.length === 1) {
+      return `${head} ${printKeyValue(keys[0], object[keys[0]])}${tail}`;
+    }
+  }
+
+  const printedComments =
+    comments
+      .split(os.EOL)
+      .map(textLine => `${start} ${textLine}`)
+      .join(os.EOL) + os.EOL;
+
+  return (
+    head +
+    line +
+    (comments ? printedComments : '') +
+    (comments && keys.length ? start + line : '') +
+    printedObject +
+    tail
+  );
+}
+
+function printKeyValue(key, value) {
+  return `@${key} ${value}`.trim();
+}
+
 exports.extract = extract;
 exports.parse = parse;
+exports.print = print;