[CFE] Add PRESUBMIT.py that runs a little smoke testing

Runs pkg/front_end/tool/smoke_test_quick.dart if changing either
* A .dart file, or
* A messages.yaml file
inside the front_end folder.

Change-Id: I466fda1436806e280e38f90afe77f1c7aa53d021
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/113321
Commit-Queue: Jens Johansen <jensj@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>

pkg/front_end/PRESUBMIT.py

@@ -0,0 +1,61 @@
+# Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE file.
+"""Front-end specific presubmit script.
+
+See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
+for more details about the presubmit API built into gcl.
+"""
+
+import imp
+import os.path
+import subprocess
+
+
+def runSmokeTest(input_api, output_api):
+    hasChangedFiles = False
+    for git_file in input_api.AffectedTextFiles():
+        filename = git_file.AbsoluteLocalPath()
+        if filename.endswith(".dart") or filename.endswith("messages.yaml"):
+            hasChangedFiles = True
+            break
+
+    if hasChangedFiles:
+        local_root = input_api.change.RepositoryRoot()
+        utils = imp.load_source('utils',
+                        os.path.join(local_root, 'tools', 'utils.py'))
+        dart = os.path.join(utils.CheckedInSdkPath(), 'bin', 'dart')
+        smoke_test = os.path.join(local_root, 'pkg', 'front_end', 'tool',
+                                  'smoke_test_quick.dart')
+
+        windows = utils.GuessOS() == 'win32'
+        if windows:
+            dart += '.exe'
+
+        if not os.path.isfile(dart):
+            print('WARNING: dart not found: %s' % dart)
+            return []
+
+        if not os.path.isfile(smoke_test):
+            print('WARNING: Front-end smoke test not found: %s' % smoke_test)
+            return []
+
+        args = [dart, smoke_test]
+        process = subprocess.Popen(
+            args, stdout=subprocess.PIPE, stdin=subprocess.PIPE)
+        outs, _ = process.communicate()
+
+        if process.returncode != 0:
+            return [output_api.PresubmitError(
+                    'Front-end smoke test failure(s):',
+                    long_text=outs)]
+
+    return []
+
+
+def CheckChangeOnCommit(input_api, output_api):
+    return runSmokeTest(input_api, output_api)
+
+
+def CheckChangeOnUpload(input_api, output_api):
+    return runSmokeTest(input_api, output_api)