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import contextlib
import functools
import inspect
import os
from platform import uname
from pathlib import Path
import shutil
import string
import sys
import warnings
from packaging.version import parse as parse_version
import matplotlib.style
import matplotlib.units
import matplotlib.testing
from matplotlib import _pylab_helpers, cbook, ft2font, pyplot as plt, ticker
from matplotlib.figure import Figure
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")
def _check_freetype_version(ver):
if ver is None:
return True
if isinstance(ver, str):
ver = (ver, ver)
ver = [parse_version(x) for x in ver]
found = parse_version(ft2font.__freetype_version__)
return ver[0] <= found <= ver[1]
def _checked_on_freetype_version(required_freetype_version):
import pytest
return pytest.mark.xfail(
not _check_freetype_version(required_freetype_version),
reason=f"Mismatched version of freetype. "
f"Test requires '{required_freetype_version}', "
f"you have '{ft2font.__freetype_version__}'",
raises=ImageComparisonFailure, strict=False)
def remove_ticks_and_titles(figure):
figure.suptitle("")
null_formatter = ticker.NullFormatter()
def remove_ticks(ax):
"""Remove ticks in *ax* and all its child 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
for child in ax.child_axes:
remove_ticks(child)
for ax in figure.get_axes():
remove_ticks(ax)
@contextlib.contextmanager
def _collect_new_figures():
"""
After::
with _collect_new_figures() as figs:
some_code()
the list *figs* contains the figures that have been created during the
execution of ``some_code``, sorted by figure number.
"""
managers = _pylab_helpers.Gcf.figs
preexisting = [manager for manager in managers.values()]
new_figs = []
try:
yield new_figs
finally:
new_managers = sorted([manager for manager in managers.values()
if manager not in preexisting],
key=lambda manager: manager.num)
new_figs[:] = [manager.canvas.figure for manager in new_managers]
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)
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:
if 'microsoft' in uname().release.lower():
raise OSError # On WSL, symlink breaks silently
if sys.platform == 'emscripten':
raise OSError
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, fig, baseline, extension, *, _lock=False):
__tracebackhide__ = True
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 contextlib.nullcontext())
with lock:
try:
fig.savefig(actual_path, **kwargs)
finally:
# Matplotlib has an autouse fixture to close figures, but this
# makes things more convenient for third-party users.
plt.close(fig)
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
KEYWORD_ONLY = inspect.Parameter.KEYWORD_ONLY
def decorator(func):
old_sig = inspect.signature(func)
@functools.wraps(func)
@pytest.mark.parametrize('extension', extensions)
@matplotlib.style.context(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
if extension not in comparable_formats():
reason = {
'gif': 'because ImageMagick is not installed',
'pdf': 'because Ghostscript is not installed',
'eps': 'because Ghostscript is not installed',
'svg': 'because Inkscape is not installed',
}.get(extension, 'on this system')
pytest.skip(f"Cannot compare {extension} files {reason}")
img = _ImageComparisonBase(func, tol=tol, remove_text=remove_text,
savefig_kwargs=savefig_kwargs)
matplotlib.testing.set_font_settings_for_testing()
with _collect_new_figures() as figs:
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(figs) == len(our_baseline_images), (
f"Test generated {len(figs)} images but there are "
f"{len(our_baseline_images)} baseline images")
for fig, baseline in zip(figs, our_baseline_images):
img.compare(fig, 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
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: 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 check_figures_equal(*, extensions=("png", ), tol=0):
"""
Decorator for test cases that generate and compare two figures.
The decorated function must take two keyword arguments, *fig_test*
and *fig_ref*, and draw the test and reference images on them.
After the function returns, the figures are saved and compared.
This decorator should be preferred over `image_comparison` when possible in
order to keep the size of the test suite from ballooning.
Parameters
----------
extensions : list, default: ["png"]
The extensions to test. Supported extensions are "png", "pdf", "svg".
Testing with the one default extension is sufficient if the output is not
format dependent, e.g. if you test that a ``bar()`` plot yields the same
result as some manually placed Rectangles. You should use all extensions
if a renderer property is involved, e.g. correct alpha blending.
tol : float
The RMS threshold above which the test is considered failed.
Raises
------
RuntimeError
If any new figures are created (and not subsequently closed) inside
the test function.
Examples
--------
Check that calling `.Axes.plot` with a single argument plots it against
``[0, 1, 2, ...]``::
@check_figures_equal()
def test_plot(fig_test, fig_ref):
fig_test.subplots().plot([1, 3, 5])
fig_ref.subplots().plot([0, 1, 2], [1, 3, 5])
"""
ALLOWED_CHARS = set(string.digits + string.ascii_letters + '_-[]()')
KEYWORD_ONLY = inspect.Parameter.KEYWORD_ONLY
def decorator(func):
import pytest
_, result_dir = _image_directories(func)
old_sig = inspect.signature(func)
if not {"fig_test", "fig_ref"}.issubset(old_sig.parameters):
raise ValueError("The decorated function must have at least the "
"parameters 'fig_test' and 'fig_ref', but your "
f"function has the signature {old_sig}")
@pytest.mark.parametrize("ext", extensions)
def wrapper(*args, ext, request, **kwargs):
if 'ext' in old_sig.parameters:
kwargs['ext'] = ext
if 'request' in old_sig.parameters:
kwargs['request'] = request
file_name = "".join(c for c in request.node.name
if c in ALLOWED_CHARS)
fig_test = Figure()
fig_ref = Figure()
func(*args, fig_test=fig_test, fig_ref=fig_ref, **kwargs)
if len(fig_test.get_children()) == 1 and len(fig_ref.get_children()) == 1:
# no artists have been added. The only child is fig.patch.
raise RuntimeError("Both figures are empty. Make sure you are "
"plotting to fig_test or fig_ref.")
test_image_path = result_dir / (file_name + "." + ext)
ref_image_path = result_dir / (file_name + "-expected." + ext)
fig_test.savefig(test_image_path)
fig_ref.savefig(ref_image_path)
_raise_on_image_difference(
ref_image_path, test_image_path, tol=tol
)
parameters = [
param
for param in old_sig.parameters.values()
if param.name not in {"fig_test", "fig_ref"}
]
if 'ext' not in old_sig.parameters:
parameters += [inspect.Parameter("ext", 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
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(inspect.getfile(func))
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