Add js_interface_generator for generating extensions interfaces

tools/json_schema_compiler/js_externs_generator_test.py

 #!/usr/bin/env python
 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import idl_schema
 import json_parse
 from js_externs_generator import JsExternsGenerator
 from datetime import datetime
 import model
 import sys
 import unittest
 
-COPYRIGHT = ("""// Copyright %s The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-""" % datetime.now().year)
-
-INFO = """// This file was generated by:
-//   %s.
-// NOTE: The format of types has changed. 'FooType' is now
-//   'chrome.%s.FooType'.
-// Please run the closure compiler before committing changes.
-// See https://code.google.com/p/chromium/wiki/ClosureCompilation.
-"""
-
 # The contents of a fake idl file.
 fake_idl = """
 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // A totally fake API.
 namespace fakeApi {
   enum Greek {
     ALPHA,
@@ skipping 41 matching lines @@
   };
 
   interface Events {
     // Fired when we realize it's a trap!
     static void onTrapDetected(Baz baz);
   };
 };
 """
 
 # The output we expect from our fake idl file.
-expected_output = COPYRIGHT + "\n" + (INFO % (sys.argv[0], "fakeApi")) + """
-/** @fileoverview Externs generated from namespace: fakeApi */
+expected_output = JsExternsGenerator.GetHeader(sys.argv[0], 'fakeApi') + """

[Devlin, 2015/12/07 18:55:27]

I slightly prefer having this hard-coded, even if it's simplistic.  Just in the
spirit of testing literal expected output, vs relying on internal functions.

Also, if this allows us to make GetHeader non-static (this is the only other use
of it I saw?), that's an added win.

[stevenjb, 2015/12/07 19:49:32]

Sigh. The previous way isn't any better IMHO because we a) define INFO above and
b) pass multiple arguments to it.

I will go ahead and explicitly embed the entire expected header (passing just
year and tool name), although I feel it falls pretty firmly into the category of
testing something that doesn't really need testing, i.e. adding maintenance cost
(already kinda high) without much benefit.

 
 /**
  * @const
  */
 chrome.fakeApi = {};
 
 /**
  * @enum {string}
  * @see https://developer.chrome.com/extensions/fakeApi#type-Greek
  */
@@ skipping 54 matching lines @@
  * @deprecated Use a new method.
  * @see https://developer.chrome.com/extensions/fakeApi#method-returnString
  */
 chrome.fakeApi.returnString = function() {};
 
 /**
  * Fired when we realize it's a trap!
  * @type {!ChromeEvent}
  * @see https://developer.chrome.com/extensions/fakeApi#event-onTrapDetected
  */
-chrome.fakeApi.onTrapDetected;
-"""
+chrome.fakeApi.onTrapDetected;"""
 
 
 fake_json = """// Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 [
   {
     "namespace": "fakeJson",
     "description": "Fake JSON API Stuff",
@@ skipping 52 matching lines @@
         "type": "object",
         "properties": {
           "str": { "type": "string" },
           "int": { "type": "number" }
         }
       }
     } ]
   }
 ]"""
 
-json_expected = COPYRIGHT + "\n" + (INFO % (sys.argv[0], "fakeJson")) + """
-/** @fileoverview Externs generated from namespace: fakeJson */
+json_expected = JsExternsGenerator.GetHeader(sys.argv[0], 'fakeJson') + """
 
 /**
  * @const
  */
 chrome.fakeJson = {};
 
 /**
  * @enum {string}
  * @see https://developer.chrome.com/extensions/fakeJson#type-CrazyEnum
  */
@@ skipping 15 matching lines @@
  *     description that causes problems!
  * @param {function({
  *   str: string
  * }):void} callback The callback to this heinous method
  * @return {{
  *   str: string,
  *   int: number
  * }}
  * @see https://developer.chrome.com/extensions/fakeJson#method-funcWithInlineObj
  */
-chrome.fakeJson.funcWithInlineObj = function(inlineObj, callback) {};
-"""
+chrome.fakeJson.funcWithInlineObj = function(inlineObj, callback) {};"""
 
 
 class JsExternGeneratorTest(unittest.TestCase):
   def _GetNamespace(self, fake_content, filename, is_idl):
     """Returns a namespace object for the given content"""
     api_def = (idl_schema.Process(fake_content, filename) if is_idl
         else json_parse.Parse(fake_content))
     m = model.Model()
     return m.AddNamespace(api_def[0], filename)
 
   def setUp(self):
     self.maxDiff = None # Lets us see the full diff when inequal.
 
   def testBasic(self):
     namespace = self._GetNamespace(fake_idl, 'fake_api.idl', True)
     self.assertMultiLineEqual(expected_output,
                               JsExternsGenerator().Generate(namespace).Render())
 
   def testJsonWithInlineObjects(self):
     namespace = self._GetNamespace(fake_json, 'fake_api.json', False)
     self.assertMultiLineEqual(json_expected,
                               JsExternsGenerator().Generate(namespace).Render())
 
 
 if __name__ == '__main__':
   unittest.main()