import contextlib
from distutils.version import StrictVersion
import functools
import inspect
import os
from pathlib import Path
import shutil
import string
import sys
import unittest
import warnings
try:
from contextlib import nullcontext
except ImportError:
from contextlib import ExitStack as nullcontext # Py3.6.
import matplotlib as mpl
import matplotlib.style
import matplotlib.units
import matplotlib.testing
from matplotlib import cbook
from matplotlib import ft2font
from matplotlib import pyplot as plt
from matplotlib import ticker
from .compare import comparable_formats, compare_images, make_test_filename
from .exceptions import ImageComparisonFailure
@contextlib.contextmanager
def _cleanup_cm():
orig_units_registry = matplotlib.units.registry.copy()
try:
with warnings.catch_warnings(), matplotlib.rc_context():
yield
finally:
matplotlib.units.registry.clear()
matplotlib.units.registry.update(orig_units_registry)
plt.close("all")
[docs]class CleanupTestCase(unittest.TestCase):
"""A wrapper for unittest.TestCase that includes cleanup operations."""
[docs] @classmethod
def setUpClass(cls):
cls._cm = _cleanup_cm().__enter__()
[docs] @classmethod
def tearDownClass(cls):
cls._cm.__exit__(None, None, None)
[docs]def cleanup(style=None):
"""
A decorator to ensure that any global state is reset before
running a test.
Parameters
----------
style : str, dict, or list, optional
The style(s) to apply. Defaults to ``["classic",
"_classic_test_patch"]``.
"""
# If cleanup is used without arguments, *style* will be a callable, and we
# pass it directly to the wrapper generator. If cleanup if called with an
# argument, it is a string naming a style, and the function will be passed
# as an argument to what we return. This is a confusing, but somewhat
# standard, pattern for writing a decorator with optional arguments.
def make_cleanup(func):
if inspect.isgeneratorfunction(func):
@functools.wraps(func)
def wrapped_callable(*args, **kwargs):
with _cleanup_cm(), matplotlib.style.context(style):
yield from func(*args, **kwargs)
else:
@functools.wraps(func)
def wrapped_callable(*args, **kwargs):
with _cleanup_cm(), matplotlib.style.context(style):
func(*args, **kwargs)
return wrapped_callable
if callable(style):
result = make_cleanup(style)
# Default of mpl_test_settings fixture and image_comparison too.
style = ["classic", "_classic_test_patch"]
return result
else:
return make_cleanup
[docs]def check_freetype_version(ver):
if ver is None:
return True
if isinstance(ver, str):
ver = (ver, ver)
ver = [StrictVersion(x) for x in ver]
found = StrictVersion(ft2font.__freetype_version__)
return ver[0] <= found <= ver[1]
def _checked_on_freetype_version(required_freetype_version):
import pytest
reason = ("Mismatched version of freetype. "
"Test requires '%s', you have '%s'" %
(required_freetype_version, ft2font.__freetype_version__))
return pytest.mark.xfail(
not check_freetype_version(required_freetype_version),
reason=reason, raises=ImageComparisonFailure, strict=False)
[docs]def remove_ticks_and_titles(figure):
figure.suptitle("")
null_formatter = ticker.NullFormatter()
for ax in figure.get_axes():
ax.set_title("")
ax.xaxis.set_major_formatter(null_formatter)
ax.xaxis.set_minor_formatter(null_formatter)
ax.yaxis.set_major_formatter(null_formatter)
ax.yaxis.set_minor_formatter(null_formatter)
try:
ax.zaxis.set_major_formatter(null_formatter)
ax.zaxis.set_minor_formatter(null_formatter)
except AttributeError:
pass
def _raise_on_image_difference(expected, actual, tol):
__tracebackhide__ = True
err = compare_images(expected, actual, tol, in_decorator=True)
if err:
for key in ["actual", "expected", "diff"]:
err[key] = os.path.relpath(err[key])
raise ImageComparisonFailure(
('images not close (RMS %(rms).3f):'
'\n\t%(actual)s\n\t%(expected)s\n\t%(diff)s') % err)
def _skip_if_format_is_uncomparable(extension):
import pytest
return pytest.mark.skipif(
extension not in comparable_formats(),
reason='Cannot compare {} files on this system'.format(extension))
def _mark_skip_if_format_is_uncomparable(extension):
import pytest
if isinstance(extension, str):
name = extension
marks = []
elif isinstance(extension, tuple):
# Extension might be a pytest ParameterSet instead of a plain string.
# Unfortunately, this type is not exposed, so since it's a namedtuple,
# check for a tuple instead.
name, = extension.values
marks = [*extension.marks]
else:
# Extension might be a pytest marker instead of a plain string.
name, = extension.args
marks = [extension.mark]
return pytest.param(name,
marks=[*marks, _skip_if_format_is_uncomparable(name)])
class _ImageComparisonBase:
"""
Image comparison base class
This class provides *just* the comparison-related functionality and avoids
any code that would be specific to any testing framework.
"""
def __init__(self, func, tol, remove_text, savefig_kwargs):
self.func = func
self.baseline_dir, self.result_dir = _image_directories(func)
self.tol = tol
self.remove_text = remove_text
self.savefig_kwargs = savefig_kwargs
def copy_baseline(self, baseline, extension):
baseline_path = self.baseline_dir / baseline
orig_expected_path = baseline_path.with_suffix(f'.{extension}')
if extension == 'eps' and not orig_expected_path.exists():
orig_expected_path = orig_expected_path.with_suffix('.pdf')
expected_fname = make_test_filename(
self.result_dir / orig_expected_path.name, 'expected')
try:
# os.symlink errors if the target already exists.
with contextlib.suppress(OSError):
os.remove(expected_fname)
try:
os.symlink(orig_expected_path, expected_fname)
except OSError: # On Windows, symlink *may* be unavailable.
shutil.copyfile(orig_expected_path, expected_fname)
except OSError as err:
raise ImageComparisonFailure(
f"Missing baseline image {expected_fname} because the "
f"following file cannot be accessed: "
f"{orig_expected_path}") from err
return expected_fname
def compare(self, idx, baseline, extension, *, _lock=False):
__tracebackhide__ = True
fignum = plt.get_fignums()[idx]
fig = plt.figure(fignum)
if self.remove_text:
remove_ticks_and_titles(fig)
actual_path = (self.result_dir / baseline).with_suffix(f'.{extension}')
kwargs = self.savefig_kwargs.copy()
if extension == 'pdf':
kwargs.setdefault('metadata',
{'Creator': None, 'Producer': None,
'CreationDate': None})
lock = cbook._lock_path(actual_path) if _lock else nullcontext()
with lock:
fig.savefig(actual_path, **kwargs)
expected_path = self.copy_baseline(baseline, extension)
_raise_on_image_difference(expected_path, actual_path, self.tol)
def _pytest_image_comparison(baseline_images, extensions, tol,
freetype_version, remove_text, savefig_kwargs,
style):
"""
Decorate function with image comparison for pytest.
This function creates a decorator that wraps a figure-generating function
with image comparison code.
"""
import pytest
extensions = map(_mark_skip_if_format_is_uncomparable, extensions)
KEYWORD_ONLY = inspect.Parameter.KEYWORD_ONLY
def decorator(func):
old_sig = inspect.signature(func)
@functools.wraps(func)
@pytest.mark.parametrize('extension', extensions)
@pytest.mark.style(style)
@_checked_on_freetype_version(freetype_version)
@functools.wraps(func)
def wrapper(*args, extension, request, **kwargs):
__tracebackhide__ = True
if 'extension' in old_sig.parameters:
kwargs['extension'] = extension
if 'request' in old_sig.parameters:
kwargs['request'] = request
img = _ImageComparisonBase(func, tol=tol, remove_text=remove_text,
savefig_kwargs=savefig_kwargs)
matplotlib.testing.set_font_settings_for_testing()
func(*args, **kwargs)
# If the test is parametrized in any way other than applied via
# this decorator, then we need to use a lock to prevent two
# processes from touching the same output file.
needs_lock = any(
marker.args[0] != 'extension'
for marker in request.node.iter_markers('parametrize'))
if baseline_images is not None:
our_baseline_images = baseline_images
else:
# Allow baseline image list to be produced on the fly based on
# current parametrization.
our_baseline_images = request.getfixturevalue(
'baseline_images')
assert len(plt.get_fignums()) == len(our_baseline_images), (
"Test generated {} images but there are {} baseline images"
.format(len(plt.get_fignums()), len(our_baseline_images)))
for idx, baseline in enumerate(our_baseline_images):
img.compare(idx, baseline, extension, _lock=needs_lock)
parameters = list(old_sig.parameters.values())
if 'extension' not in old_sig.parameters:
parameters += [inspect.Parameter('extension', KEYWORD_ONLY)]
if 'request' not in old_sig.parameters:
parameters += [inspect.Parameter("request", KEYWORD_ONLY)]
new_sig = old_sig.replace(parameters=parameters)
wrapper.__signature__ = new_sig
# Reach a bit into pytest internals to hoist the marks from our wrapped
# function.
new_marks = getattr(func, 'pytestmark', []) + wrapper.pytestmark
wrapper.pytestmark = new_marks
return wrapper
return decorator
[docs]def image_comparison(baseline_images, extensions=None, tol=0,
freetype_version=None, remove_text=False,
savefig_kwarg=None,
# Default of mpl_test_settings fixture and cleanup too.
style=("classic", "_classic_test_patch")):
"""
Compare images generated by the test with those specified in
*baseline_images*, which must correspond, else an `ImageComparisonFailure`
exception will be raised.
Parameters
----------
baseline_images : list or None
A list of strings specifying the names of the images generated by
calls to `.Figure.savefig`.
If *None*, the test function must use the ``baseline_images`` fixture,
either as a parameter or with `pytest.mark.usefixtures`. This value is
only allowed when using pytest.
extensions : None or list of str
The list of extensions to test, e.g. ``['png', 'pdf']``.
If *None*, defaults to all supported extensions: png, pdf, and svg.
When testing a single extension, it can be directly included in the
names passed to *baseline_images*. In that case, *extensions* must not
be set.
In order to keep the size of the test suite from ballooning, we only
include the ``svg`` or ``pdf`` outputs if the test is explicitly
exercising a feature dependent on that backend (see also the
`check_figures_equal` decorator for that purpose).
tol : float, default: 0
The RMS threshold above which the test is considered failed.
Due to expected small differences in floating-point calculations, on
32-bit systems an additional 0.06 is added to this threshold.
freetype_version : str or tuple
The expected freetype version or range of versions for this test to
pass.
remove_text : bool
Remove the title and tick text from the figure before comparison. This
is useful to make the baseline images independent of variations in text
rendering between different versions of FreeType.
This does not remove other, more deliberate, text, such as legends and
annotations.
savefig_kwarg : dict
Optional arguments that are passed to the savefig method.
style : str, dict, or list
The optional style(s) to apply to the image test. The test itself
can also apply additional styles if desired. Defaults to ``["classic",
"_classic_test_patch"]``.
"""
if baseline_images is not None:
# List of non-empty filename extensions.
baseline_exts = [*filter(None, {Path(baseline).suffix[1:]
for baseline in baseline_images})]
if baseline_exts:
if extensions is not None:
raise ValueError(
"When including extensions directly in 'baseline_images', "
"'extensions' cannot be set as well")
if len(baseline_exts) > 1:
raise ValueError(
"When including extensions directly in 'baseline_images', "
"all baselines must share the same suffix")
extensions = baseline_exts
baseline_images = [ # Chop suffix out from baseline_images.
Path(baseline).stem for baseline in baseline_images]
if extensions is None:
# Default extensions to test, if not set via baseline_images.
extensions = ['png', 'pdf', 'svg']
if savefig_kwarg is None:
savefig_kwarg = dict() # default no kwargs to savefig
if sys.maxsize <= 2**32:
tol += 0.06
return _pytest_image_comparison(
baseline_images=baseline_images, extensions=extensions, tol=tol,
freetype_version=freetype_version, remove_text=remove_text,
savefig_kwargs=savefig_kwarg, style=style)
def _image_directories(func):
"""
Compute the baseline and result image directories for testing *func*.
For test module ``foo.bar.test_baz``, the baseline directory is at
``foo/bar/baseline_images/test_baz`` and the result directory at
``$(pwd)/result_images/test_baz``. The result directory is created if it
doesn't exist.
"""
module_path = Path(sys.modules[func.__module__].__file__)
baseline_dir = module_path.parent / "baseline_images" / module_path.stem
result_dir = Path().resolve() / "result_images" / module_path.stem
result_dir.mkdir(parents=True, exist_ok=True)
return baseline_dir, result_dir
