1 files changed, 124 insertions, 0 deletions
diff --git a/catapult/common/py_utils/py_utils/expectations_parser.py b/catapult/common/py_utils/py_utils/expectations_parser.py
new file mode 100644
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+++ b/catapult/common/py_utils/py_utils/expectations_parser.py
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+# Copyright 2017 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 re
+
+
+class ParseError(Exception):
+  pass
+
+
+class Expectation(object):
+  def __init__(self, reason, test, conditions, results):
+    """Constructor for expectations.
+
+    Args:
+      reason: String that indicates the reason for disabling.
+      test: String indicating which test is being disabled.
+      conditions: List of tags indicating which conditions to disable for.
+          Conditions are combined using logical and. Example: ['Mac', 'Debug']
+      results: List of outcomes for test. Example: ['Skip', 'Pass']
+    """
+    assert isinstance(reason, basestring) or reason is None
+    self._reason = reason
+    assert isinstance(test, basestring)
+    self._test = test
+    assert isinstance(conditions, list)
+    self._conditions = conditions
+    assert isinstance(results, list)
+    self._results = results
+
+  def __eq__(self, other):
+    return (self.reason == other.reason and
+            self.test == other.test and
+            self.conditions == other.conditions and
+            self.results == other.results)
+
+  @property
+  def reason(self):
+    return self._reason
+
+  @property
+  def test(self):
+    return self._test
+
+  @property
+  def conditions(self):
+    return self._conditions
+
+  @property
+  def results(self):
+    return self._results
+
+
+class TestExpectationParser(object):
+  """Parse expectations data in TA/DA format.
+
+  This parser covers the 'tagged' test lists format in:
+      bit.ly/chromium-test-list-format
+
+  Takes raw expectations data as a string read from the TA/DA expectation file
+  in the format:
+
+    # This is an example expectation file.
+    #
+    # tags: Mac Mac10.10 Mac10.11
+    # tags: Win Win8
+
+    crbug.com/123 [ Win ] benchmark/story [ Skip ]
+    ...
+  """
+
+  TAG_TOKEN = '# tags:'
+  _MATCH_STRING = r'^(?:(crbug.com/\d+) )?'  # The bug field (optional).
+  _MATCH_STRING += r'(?:\[ (.+) \] )?' # The label field (optional).
+  _MATCH_STRING += r'(\S+) ' # The test path field.
+  _MATCH_STRING += r'\[ ([^\[.]+) \]'  # The expectation field.
+  _MATCH_STRING += r'(\s+#.*)?$' # End comment (optional).
+  MATCHER = re.compile(_MATCH_STRING)
+
+  def __init__(self, raw_data):
+    self._tags = []
+    self._expectations = []
+    self._ParseRawExpectationData(raw_data)
+
+  def _ParseRawExpectationData(self, raw_data):
+    for count, line in list(enumerate(raw_data.splitlines(), start=1)):
+      # Handle metadata and comments.
+      if line.startswith(self.TAG_TOKEN):
+        for word in line[len(self.TAG_TOKEN):].split():
+          # Expectations must be after all tags are declared.
+          if self._expectations:
+            raise ParseError('Tag found after first expectation.')
+          self._tags.append(word)
+      elif line.startswith('#') or not line:
+        continue  # Ignore, it is just a comment or empty.
+      else:
+        self._expectations.append(
+            self._ParseExpectationLine(count, line, self._tags))
+
+  def _ParseExpectationLine(self, line_number, line, tags):
+    match = self.MATCHER.match(line)
+    if not match:
+      raise ParseError(
+          'Expectation has invalid syntax on line %d: %s'
+          % (line_number, line))
+    # Unused group is optional trailing comment.
+    reason, raw_conditions, test, results, _ = match.groups()
+    conditions = [c for c in raw_conditions.split()] if raw_conditions else []
+
+    for c in conditions:
+      if c not in tags:
+        raise ParseError(
+            'Condition %s not found in expectations tag data. Line %d'
+            % (c, line_number))
+    return Expectation(reason, test, conditions, [r for r in results.split()])
+
+  @property
+  def expectations(self):
+    return self._expectations
+
+  @property
+  def tags(self):
+    return self._tags