WPT: Allow setting GitHub credentials as env variables, warn when they are not set

A fresh WPT import checkout is very likely to fail when no GitHub
credentials are used due to the number of API requests we make vs.
GitHub's rate limits for unauthenticated requests.

Make things more obvious by:
* Allowing the credentials to be specified as environment variables in
  addition to a JSON file (when both are set, the JSON file specified in
  the command-line has precedence).
* Printing a warning in test_importer.py when no credentials are set and
  pointing to the documentation in //docs/testing.
* Expanding the error message in test_exporter.py to point to the same
  location.

Bug: 816390
Change-Id: I5508e024e8a13e6f597f027cd157d7abbe9b2fe1
Reviewed-on: https://chromium-review.googlesource.com/937462Reviewed-by: Philip Jägenstedt <foolip@chromium.org>
Commit-Queue: Raphael Kubo da Costa <raphael.kubo.da.costa@intel.com>
Cr-Commit-Position: refs/heads/master@{#539164}

docs/testing/web_platform_tests.md

@@ -120,9 +120,14 @@ unauthenticated requests, so it is recommended that you let `wpt-export` and
 `wpt-import` use your GitHub credentials when sending requests:
 
  1. Generate a new [personal access token](https://github.com/settings/tokens)
- 1. Create a JSON file with two keys: `GH_USER`, your GitHub user name, and
-    `GH_TOKEN`, the access token you have just generated.
- 1. Pass `--credentials-json <path-to-json>` to `wpt-export` and `wpt-import`.
+ 1. Set up your credentials by either:
+     * Setting the `GH_USER` environment variable to your GitHub user name
+       and the `GH_TOKEN` environment variable to the access token you have
+       just created **or**
+     * Creating a JSON file with two keys: `GH_USER`, your GitHub user name,
+       and `GH_TOKEN`, the access token you have just generated. After that,
+       pass `--credentials-json <path-to-json>` to `wpt-export` and
+       `wpt-import`.
 
 ### Manual import
 

third_party/WebKit/Tools/Scripts/webkitpy/w3c/common.py

@@ -24,9 +24,22 @@ _log = logging.getLogger(__name__)
 
 
 def read_credentials(host, credentials_json):
-    """Extracts credentials from a JSON file."""
+    """Extracts GitHub and Gerrit credentials.
+
+    The data is read from the environment and (optionally) a JSON file. When a
+    JSON file is specified, any variables from the environment are discarded
+    and the values are all expected to be present in the file.
+
+    Args:
+        credentials_json: Path to a JSON file containing an object with the
+            keys we want to read, or None.
+    """
+    env_credentials = {}
+    for key in ('GH_USER', 'GH_TOKEN', 'GERRIT_USER', 'GERRIT_TOKEN'):
+        if key in host.environ:
+            env_credentials[key] = host.environ[key]
     if not credentials_json:
-        return {}
+        return env_credentials
     if not host.filesystem.exists(credentials_json):
         _log.warning('Credentials JSON file not found at %s.', credentials_json)
         return {}

third_party/WebKit/Tools/Scripts/webkitpy/w3c/common_unittest.py

@@ -25,6 +25,24 @@ class CommonTest(unittest.TestCase):
     def test_get_credentials_none(self):
         self.assertEqual(read_credentials(MockHost(), None), {})
 
+    def test_get_credentials_gets_values_from_environment(self):
+        host = MockHost()
+        host.environ.update({
+            'GH_USER': 'user-github',
+            'GH_TOKEN': 'pass-github',
+            'GERRIT_USER': 'user-gerrit',
+            'GERRIT_TOKEN': 'pass-gerrit',
+            'UNUSED_VALUE': 'foo',
+        })
+        self.assertEqual(
+            read_credentials(host, None),
+            {
+                'GH_USER': 'user-github',
+                'GH_TOKEN': 'pass-github',
+                'GERRIT_USER': 'user-gerrit',
+                'GERRIT_TOKEN': 'pass-gerrit',
+            })
+
     def test_get_credentials_gets_values_from_file(self):
         host = MockHost()
         host.filesystem.write_text_file(
@@ -44,6 +62,27 @@ class CommonTest(unittest.TestCase):
                 'GERRIT_TOKEN': 'pass-gerrit',
             })
 
+    def test_get_credentials_choose_file_over_environment(self):
+        host = MockHost()
+        host.environ.update({
+            'GH_USER': 'user-github-from-env',
+            'GH_TOKEN': 'pass-github-from-env',
+            'GERRIT_USER': 'user-gerrit-from-env',
+            'GERRIT_TOKEN': 'pass-gerrit-from-env',
+        })
+        host.filesystem.write_text_file(
+            '/tmp/credentials.json',
+            json.dumps({
+                'GH_USER': 'user-github-from-json',
+                'GH_TOKEN': 'pass-github-from-json',
+            }))
+        self.assertEqual(
+            read_credentials(host, '/tmp/credentials.json'),
+            {
+                'GH_USER': 'user-github-from-json',
+                'GH_TOKEN': 'pass-github-from-json',
+            })
+
     def test_is_testharness_baseline(self):
         self.assertTrue(is_testharness_baseline('fake-test-expected.txt'))
         self.assertTrue(is_testharness_baseline('external/wpt/fake-test-expected.txt'))

third_party/WebKit/Tools/Scripts/webkitpy/w3c/test_exporter.py

@@ -48,8 +48,13 @@ class TestExporter(object):
             self.host.executive.error_output_limit = None
 
         credentials = read_credentials(self.host, options.credentials_json)
-        if not (credentials['GH_USER'] and credentials['GH_TOKEN']):
-            _log.error('Must provide both user and token for GitHub.')
+        if not (credentials.get('GH_USER') and credentials.get('GH_TOKEN')):
+            _log.error('You must provide your GitHub credentials for this '
+                       'script to work.')
+            _log.error('See https://chromium.googlesource.com/chromium/src'
+                       '/+/master/docs/testing/web_platform_tests.md'
+                       '#GitHub-credentials for instructions on how to set '
+                       'your credentials up.')
             return False
 
         self.wpt_github = self.wpt_github or WPTGitHub(self.host, credentials['GH_USER'], credentials['GH_TOKEN'])

third_party/WebKit/Tools/Scripts/webkitpy/w3c/test_importer.py

@@ -89,6 +89,14 @@ class TestImporter(object):
         credentials = read_credentials(self.host, options.credentials_json)
         gh_user = credentials.get('GH_USER')
         gh_token = credentials.get('GH_TOKEN')
+        if not gh_user or not gh_token:
+            _log.warning('You have not set your GitHub credentials. This '
+                         'script may fail with a network error when making '
+                         'an API request to GitHub.')
+            _log.warning('See https://chromium.googlesource.com/chromium/src'
+                         '/+/master/docs/testing/web_platform_tests.md'
+                         '#GitHub-credentials for instructions on how to set '
+                         'your credentials up.')
         self.wpt_github = self.wpt_github or WPTGitHub(self.host, gh_user, gh_token)
         self.git_cl = GitCL(self.host, auth_refresh_token_json=options.auth_refresh_token_json)