Added checks for tests.

PRESUBMIT will check:
  1. a new test can NOT be added to Dart 1.0 the new test can only be added to DDC.
  2. a existing Dart 1.0 test changed must have its corresponding DDC test updated too (if it exists).

Presubmit errors may appear as:

** Presubmit ERRORS **
Error: If you change a Dart 1.0 test, you must also update the DDC test:
1. Dart 1.0 test changed: tests/corelib/symbol_map_helper.dart
1. DDC  test must change: tests/corelib_2/symbol_map_helper.dart
2. Dart 1.0 test changed: tests/language/compiler_annotations.dart
2. DDC  test must change: tests/language_2/compiler_annotations.dart

R=jacobr@google.com, rnystrom@google.com

Error: New Dart 1.0 test can not be added the test must be added as a DDC test:
Fix tests:
1. New Dart 1.0  test: tests/corelib/new_test.dart
1. Should be DDC test: tests/corelib_2/new_test.dart
2. New Dart 1.0  test: tests/language/new_test.dart
2. Should be DDC test: tests/language_2/new_test.dart
Review-Url: https://codereview.chromium.org/2982043002 .

Author: terrylucas

PRESUBMIT.py

@@ -10,18 +10,19 @@
 
 import imp
 import os
+import os.path
 import scm
 import subprocess
 import tempfile
 
 def _CheckBuildStatus(input_api, output_api):
-   results = []
-   status_check = input_api.canned_checks.CheckTreeIsOpen(
-       input_api,
-       output_api,
-       json_url='http://dart-status.appspot.com/current?format=json')
-   results.extend(status_check)
-   return results
+  results = []
+  status_check = input_api.canned_checks.CheckTreeIsOpen(
+      input_api,
+      output_api,
+      json_url='http://dart-status.appspot.com/current?format=json')
+  results.extend(status_check)
+  return results
 
 def _CheckDartFormat(input_api, output_api):
   local_root = input_api.change.RepositoryRoot()
@@ -96,9 +97,81 @@ def HasFormatErrors(filename=None, contents=None):
 
   return []
 
+def _CheckNewTests(input_api, output_api):
+  testsDirectories = [
+      #    Dart 1 tests                DDC tests
+      # =================       ==========================
+      ("tests/language/",       "tests/language_2/"),
+      ("tests/corelib/",        "tests/corelib_2/"),
+      ("tests/lib/",            "tests/lib_2/"),
+      ("tests/html/",           "tests/lib_2/html/"),
+  ]
+
+  result = []
+  # Tuples of (new Dart 1 test path, expected DDC test path)
+  dart1TestsAdded = []
+  # Tuples of (original Dart test path, expected DDC test path)
+  ddcTestsExists = []
+  for f in input_api.AffectedFiles():
+    for oldPath, newPath in testsDirectories:
+      if f.LocalPath().startswith(oldPath):
+        if f.Action() == 'A':
+          # Compute where the new test should live.
+          ddcTestPath = f.LocalPath().replace(oldPath, newPath)
+          dart1TestsAdded.append((f.LocalPath(), ddcTestPath))
+        elif f.Action() == 'M':
+          # Find all modified tests in Dart 1.0
+          filename = f.LocalPath()
+          for oldPath, newPath in testsDirectories:
+            if filename.find(oldPath) == 0:
+              ddcTestFilePathAbs = "%s" % \
+                  f.AbsoluteLocalPath().replace(oldPath, newPath)
+              if os.path.isfile(ddcTestFilePathAbs):
+                #originalDart1Test.append(f.LocalPath())
+                ddcTestsExists.append((f.LocalPath(),
+                    f.LocalPath().replace(oldPath, newPath)))
+
+  # Does a Dart 2.0 DDC test exist if so it must be changed too.
+  missingDDCTestsChange = []
+  for (dartTest, ddcTest) in ddcTestsExists:
+    foundDDCTestModified = False
+    for f in input_api.AffectedFiles():
+      if f.LocalPath() == ddcTest:
+        # Found corresponding DDC test - great.
+        foundDDCTestModified = True
+        break
+    if not foundDDCTestModified:
+      # Add the tuple (dart 1 test path, DDC test path)
+      missingDDCTestsChange.append((dartTest, ddcTest))
+
+  if missingDDCTestsChange:
+    errorList = []
+    for idx, (orginalTest, ddcTest) in enumerate(missingDDCTestsChange):
+      errorList.append(
+          '%s. Dart 1.0 test changed: %s\n%s. DDC  test must change: ' \
+          '%s\n' % (idx + 1, orginalTest, idx + 1, ddcTest))
+    result.append(output_api.PresubmitError(
+        'Error: If you change a Dart 1.0 test, you must also update the DDC '
+        'test:\n%s' % ''.join(errorList)))
+
+  if dart1TestsAdded:
+    errorList = []
+    for idx, (oldTestPath, newTestPath) in enumerate(dart1TestsAdded):
+      errorList.append('%s. New Dart 1.0  test: %s\n'
+          '%s. Should be DDC test: %s\n' % \
+          (idx + 1, oldTestPath, idx + 1, newTestPath))
+    result.append(output_api.PresubmitError(
+        'Error: New Dart 1.0 test can not be added the test must be added as '
+        'a DDC test:\n'
+        'Fix tests:\n%s' % ''.join(errorList)))
+
+  return result
+
 def CheckChangeOnCommit(input_api, output_api):
   return (_CheckBuildStatus(input_api, output_api) +
+          _CheckNewTests(input_api, output_api) +
           _CheckDartFormat(input_api, output_api))
 
 def CheckChangeOnUpload(input_api, output_api):
-  return _CheckDartFormat(input_api, output_api)
+  return (_CheckNewTests(input_api, output_api) +
+          _CheckDartFormat(input_api, output_api))