TST: Allow baseline_images to be a fixture.

QuLogic · QuLogic · commit f736296e634a · 2017-04-15T02:45:30.000-04:00
The main point is it can be indirectly determined from other
parametrizations.
diff --git a/lib/matplotlib/testing/conftest.py b/lib/matplotlib/testing/conftest.py
@@ -65,7 +65,13 @@ def mpl_image_comparison_parameters(request, extension):
     # pytest won't get confused.
     # We annotate the decorated function with any parameters captured by this
     # fixture so that they can be used by the wrapper in image_comparison.
+    baseline_images = request.keywords['baseline_images'].args[0]
+    if baseline_images is None:
+        # Allow baseline image list to be produced on the fly based on current
+        # parametrization.
+        baseline_images = request.getfixturevalue('baseline_images')
+
     func = request.function
-    func.__wrapped__.parameters = (extension, )
+    func.__wrapped__.parameters = (baseline_images, extension)
     yield
     delattr(func.__wrapped__, 'parameters')
diff --git a/lib/matplotlib/testing/decorators.py b/lib/matplotlib/testing/decorators.py
@@ -344,6 +344,7 @@ def _pytest_image_comparison(baseline_images, extensions, tol,
     def decorator(func):
         @pytest.mark.usefixtures('mpl_image_comparison_parameters')
         @pytest.mark.parametrize('extension', extensions)
+        @pytest.mark.baseline_images(baseline_images)
         @pytest.mark.style(style)
         @_checked_on_freetype_version(freetype_version)
         @functools.wraps(func)
@@ -359,7 +360,7 @@ def wrapper(*args, **kwargs):
             # so that we don't need to modify the function's real signature for
             # any parametrization. Modifying the signature is very very tricky
             # and likely to confuse pytest.
-            extension, = func.parameters
+            baseline_images, extension = func.parameters
 
             assert len(plt.get_fignums()) == len(baseline_images), (
                 "Test generated {} images but there are {} baseline images"
@@ -373,7 +374,7 @@ def wrapper(*args, **kwargs):
     return decorator
 
 
-def image_comparison(baseline_images=None, extensions=None, tol=0,
+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.
@@ -385,10 +386,14 @@ def image_comparison(baseline_images=None, extensions=None, tol=0,
 
     Arguments
     ---------
-    baseline_images : list
+    baseline_images : list or None
         A list of strings specifying the names of the images generated by
         calls to :meth:`matplotlib.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 | list ]
 
         If None, defaults to all supported extensions.
@@ -415,9 +420,6 @@ def image_comparison(baseline_images=None, extensions=None, tol=0,
         '_classic_test' style.
 
     """
-    if baseline_images is None:
-        raise ValueError('baseline_images must be specified')
-
     if extensions is None:
         # default extensions to test
         extensions = ['png', 'pdf', 'svg']
@@ -432,6 +434,9 @@ def image_comparison(baseline_images=None, extensions=None, tol=0,
             freetype_version=freetype_version, remove_text=remove_text,
             savefig_kwargs=savefig_kwarg, style=style)
     else:
+        if baseline_images is None:
+            raise ValueError('baseline_images must be specified')
+
         return ImageComparisonDecorator(
             baseline_images=baseline_images, extensions=extensions, tol=tol,
             freetype_version=freetype_version, remove_text=remove_text,
