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Make image_comparison work even without the autoclose fixture. #21256

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Oct 14, 2021
+41 −18
Merged

Make image_comparison work even without the autoclose fixture. #21256

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59 changes: 41 additions & 18 deletions lib/matplotlib/testing/decorators.py
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Original file line number Diff line number Diff line change
Expand Up @@ -14,10 +14,7 @@
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 matplotlib import cbook, ft2font, pyplot as plt, ticker, _pylab_helpers
from .compare import comparable_formats, compare_images, make_test_filename
from .exceptions import ImageComparisonFailure

Expand Down Expand Up @@ -129,6 +126,29 @@ def remove_ticks(ax):
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

Expand Down Expand Up @@ -178,10 +198,8 @@ def copy_baseline(self, baseline, extension):
f"{orig_expected_path}") from err
return expected_fname

def compare(self, idx, baseline, extension, *, _lock=False):
def compare(self, fig, baseline, extension, *, _lock=False):
__tracebackhide__ = True
fignum = plt.get_fignums()[idx]
fig = plt.figure(fignum)

if self.remove_text:
remove_ticks_and_titles(fig)
Expand All @@ -196,7 +214,12 @@ def compare(self, idx, baseline, extension, *, _lock=False):
lock = (cbook._lock_path(actual_path)
if _lock else contextlib.nullcontext())
with lock:
fig.savefig(actual_path, **kwargs)
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)

Expand Down Expand Up @@ -235,7 +258,9 @@ def wrapper(*args, extension, request, **kwargs):
img = _ImageComparisonBase(func, tol=tol, remove_text=remove_text,
savefig_kwargs=savefig_kwargs)
matplotlib.testing.set_font_settings_for_testing()
func(*args, **kwargs)

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
Expand All @@ -252,11 +277,11 @@ def wrapper(*args, extension, request, **kwargs):
our_baseline_images = request.getfixturevalue(
'baseline_images')

assert len(plt.get_fignums()) == len(our_baseline_images), (
assert len(figs) == 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)
.format(len(figs), len(our_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:
Expand Down Expand Up @@ -427,11 +452,9 @@ def wrapper(*args, ext, request, **kwargs):
try:
fig_test = plt.figure("test")
fig_ref = plt.figure("reference")
# Keep track of number of open figures, to make sure test
# doesn't create any new ones
n_figs = len(plt.get_fignums())
func(*args, fig_test=fig_test, fig_ref=fig_ref, **kwargs)
if len(plt.get_fignums()) > n_figs:
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 '
Expand Down