#!/usr/bin/env python
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"""Classes for failures that occur during tests."""

import test_expectations

import cPickle


# FIXME: This is backwards.  Each TestFailure subclass should know what
# test_expectation type it corresponds too.  Then this method just
# collects them all from the failure list and returns the worst one.
def determine_result_type(failure_list):
    """Takes a set of test_failures and returns which result type best fits
    the list of failures. "Best fits" means we use the worst type of failure.

    Returns:
      one of the test_expectations result types - PASS, TEXT, CRASH, etc."""

    if not failure_list or len(failure_list) == 0:
        return test_expectations.PASS

    failure_types = [type(f) for f in failure_list]
    if FailureCrash in failure_types:
        return test_expectations.CRASH
    elif FailureTimeout in failure_types:
        return test_expectations.TIMEOUT
    elif (FailureMissingResult in failure_types or
          FailureMissingImage in failure_types or
          FailureMissingImageHash in failure_types or
          FailureMissingAudio in failure_types):
        return test_expectations.MISSING
    else:
        is_text_failure = FailureTextMismatch in failure_types
        is_image_failure = (FailureImageHashIncorrect in failure_types or
                            FailureImageHashMismatch in failure_types)
        is_reftest_failure = (FailureReftestMismatch in failure_types or
                              FailureReftestMismatchDidNotOccur in failure_types)
        is_audio_failure = (FailureAudioMismatch in failure_types)
        if is_text_failure and is_image_failure:
            return test_expectations.IMAGE_PLUS_TEXT
        elif is_text_failure:
            return test_expectations.TEXT
        elif is_image_failure or is_reftest_failure:
            return test_expectations.IMAGE
        elif is_audio_failure:
            return test_expectations.AUDIO
        else:
            raise ValueError("unclassifiable set of failures: "
                             + str(failure_types))


class TestFailure(object):
    """Abstract base class that defines the failure interface."""

    @staticmethod
    def loads(s):
        """Creates a TestFailure object from the specified string."""
        return cPickle.loads(s)

    @staticmethod
    def message():
        """Returns a string describing the failure in more detail."""
        raise NotImplementedError

    def __eq__(self, other):
        return self.__class__.__name__ == other.__class__.__name__

    def __ne__(self, other):
        return self.__class__.__name__ != other.__class__.__name__

    def __hash__(self):
        return hash(self.__class__.__name__)

    def dumps(self):
        """Returns the string/JSON representation of a TestFailure."""
        return cPickle.dumps(self)

    def should_kill_dump_render_tree(self):
        """Returns True if we should kill DumpRenderTree before the next
        test."""
        return False


class FailureTimeout(TestFailure):
    """Test timed out.  We also want to restart DumpRenderTree if this
    happens."""
    def __init__(self, is_reftest=False):
        self.is_reftest = is_reftest

    @staticmethod
    def message():
        return "Test timed out"

    def should_kill_dump_render_tree(self):
        return True


class FailureCrash(TestFailure):
    """DumpRenderTree crashed."""
    def __init__(self, is_reftest=False):
        self.is_reftest = is_reftest

    @staticmethod
    def message():
        return "DumpRenderTree crashed"

    def should_kill_dump_render_tree(self):
        return True


class FailureMissingResult(TestFailure):
    """Expected result was missing."""

    @staticmethod
    def message():
        return "No expected results found"


class FailureTextMismatch(TestFailure):
    """Text diff output failed."""

    @staticmethod
    def message():
        return "Text diff mismatch"


class FailureMissingImageHash(TestFailure):
    """Actual result hash was missing."""
    # Chrome doesn't know to display a .checksum file as text, so don't bother
    # putting in a link to the actual result.

    @staticmethod
    def message():
        return "No expected image hash found"


class FailureMissingImage(TestFailure):
    """Actual result image was missing."""

    @staticmethod
    def message():
        return "No expected image found"


class FailureImageHashMismatch(TestFailure):
    """Image hashes didn't match."""

    @staticmethod
    def message():
        # We call this a simple image mismatch to avoid confusion, since
        # we link to the PNGs rather than the checksums.
        return "Image mismatch"


class FailureImageHashIncorrect(TestFailure):
    """Actual result hash is incorrect."""
    # Chrome doesn't know to display a .checksum file as text, so don't bother
    # putting in a link to the actual result.

    @staticmethod
    def message():
        return "Images match, expected image hash incorrect. "


class FailureReftestMismatch(TestFailure):
    """The result didn't match the reference rendering."""

    @staticmethod
    def message():
        return "Mismatch with reference"


class FailureReftestMismatchDidNotOccur(TestFailure):
    """Unexpected match between the result and the reference rendering."""

    @staticmethod
    def message():
        return "Mismatch with the reference did not occur"


class FailureMissingAudio(TestFailure):
    """Actual result image was missing."""

    @staticmethod
    def message():
        return "No expected audio found"


class FailureAudioMismatch(TestFailure):
    """Audio files didn't match."""

    @staticmethod
    def message():
        return "Audio mismatch"


# Convenient collection of all failure classes for anything that might
# need to enumerate over them all.
ALL_FAILURE_CLASSES = (FailureTimeout, FailureCrash, FailureMissingResult,
                       FailureTextMismatch, FailureMissingImageHash,
                       FailureMissingImage, FailureImageHashMismatch,
                       FailureImageHashIncorrect, FailureReftestMismatch,
                       FailureReftestMismatchDidNotOccur)