Use skipif instead of xfail when test dependencies are missing.

In such cases, there's no need to even try running the test and get an
exception out of it.

Author: anntzer

lib/matplotlib/tests/test_backend_pdf.py

@@ -14,7 +14,7 @@
                                             _determinism_check)
 
 
-needs_usetex = pytest.mark.xfail(
+needs_usetex = pytest.mark.skipif(
     not checkdep_usetex(True),
     reason="This test needs a TeX installation")
 

lib/matplotlib/tests/test_backend_ps.py

@@ -15,12 +15,10 @@
                                             _determinism_check)
 
 
-needs_ghostscript = pytest.mark.xfail(
+needs_ghostscript = pytest.mark.skipif(
     matplotlib.checkdep_ghostscript()[0] is None,
     reason="This test needs a ghostscript installation")
-
-
-needs_usetex = pytest.mark.xfail(
+needs_usetex = pytest.mark.skipif(
     not matplotlib.checkdep_usetex(True),
     reason="This test needs a TeX installation")
 

lib/matplotlib/tests/test_backend_qt4.py

@@ -24,7 +24,7 @@
     py_qt_ver = QtCore.__version_info__[0]
 
 if py_qt_ver != 4:
-    pytestmark = pytest.mark.xfail(reason='Qt4 is not available')
+    pytestmark = pytest.mark.skipif(reason='Qt4 is not available')
 
 
 @pytest.mark.backend('Qt4Agg')

lib/matplotlib/tests/test_backend_svg.py

@@ -12,7 +12,7 @@
 from matplotlib import dviread
 
 
-needs_usetex = pytest.mark.xfail(
+needs_usetex = pytest.mark.skipif(
     not matplotlib.checkdep_usetex(True),
     reason="This test needs a TeX installation")
 

lib/matplotlib/tests/test_image.py

@@ -21,14 +21,6 @@
 import pytest
 
 
-try:
-    from PIL import Image
-    HAS_PIL = True
-except ImportError:
-    HAS_PIL = False
-needs_pillow = pytest.mark.xfail(not HAS_PIL, reason='Test requires Pillow')
-
-
 @image_comparison(baseline_images=['image_interps'], style='mpl20')
 def test_image_interps():
     'make the basic nearest, bilinear and bicubic interps'
@@ -111,17 +103,17 @@ def test_image_python_io():
     plt.imread(buffer)
 
 
-@needs_pillow
 def test_imread_pil_uint16():
+    pytest.importorskip("PIL")
     img = plt.imread(os.path.join(os.path.dirname(__file__),
                      'baseline_images', 'test_image', 'uint16.tif'))
     assert img.dtype == np.uint16
     assert np.sum(img) == 134184960
 
 
 @pytest.mark.skipif(sys.version_info < (3, 6), reason="requires Python 3.6+")
-@needs_pillow
 def test_imread_fspath():
+    pytest.importorskip("PIL")
     from pathlib import Path
     img = plt.imread(
         Path(__file__).parent / 'baseline_images/test_image/uint16.tif')
@@ -498,8 +490,8 @@ def test_nonuniformimage_setnorm():
     im.set_norm(plt.Normalize())
 
 
-@needs_pillow
 def test_jpeg_2d():
+    Image = pytest.importorskip('PIL.Image')
     # smoke test that mode-L pillow images work.
     imd = np.ones((10, 10), dtype='uint8')
     for i in range(10):
@@ -510,8 +502,9 @@ def test_jpeg_2d():
     ax.imshow(im)
 
 
-@needs_pillow
 def test_jpeg_alpha():
+    Image = pytest.importorskip('PIL.Image')
+
     plt.figure(figsize=(1, 1), dpi=300)
     # Create an image that is all black, with a gradient from 0-1 in
     # the alpha channel from left to right.

lib/matplotlib/tests/test_text.py

@@ -10,7 +10,7 @@
 from matplotlib.testing.decorators import image_comparison
 
 
-needs_usetex = pytest.mark.xfail(
+needs_usetex = pytest.mark.skipif(
     not matplotlib.checkdep_usetex(True),
     reason="This test needs a TeX installation")