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 .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 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 = { '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 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 check_figures_equal(*, extensions=("png", "pdf", "svg"), 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", "pdf", "svg"] The extensions to test. 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) try: fig_test = plt.figure("test") fig_ref = plt.figure("reference") with _collect_new_figures() as figs: func(*args, fig_test=fig_test, fig_ref=fig_ref, **kwargs) if figs: raise RuntimeError('Number of open figures changed during ' 'test. Make sure you are plotting to ' 'fig_test or fig_ref, or if this is ' 'deliberate explicitly close the ' 'new figure(s) inside the test.') 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 ) finally: plt.close(fig_test) plt.close(fig_ref) 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