matplotlib · anntzer · Jun 5, 2019
diff --git a/doc/api/next_api_changes/deprecations.rst b/doc/api/next_api_changes/deprecations.rst
@@ -41,3 +41,11 @@ Flags containing "U" passed to `.cbook.to_filehandle` and `.cbook.open_file_cm`
 Please remove "U" from flags passed to `.cbook.to_filehandle` and
 `.cbook.open_file_cm`.  This is consistent with their removal from `open` in
 Python 3.9.
+
+``matplotlib.checkdep_usetex``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+``matplotlib.checkdep_usetex`` is deprecated (it checks for the presence of
+tex, dvipng, and ghostscript, even though ghostscript is not needed for raster
+output and dvipng is not needed for vector output).  The
+``matplotlib.testing.decorators.needs_usetex`` is a partial replacement to
+decorate tests that depend on usetex mode.
diff --git a/lib/matplotlib/__init__.py b/lib/matplotlib/__init__.py
@@ -504,6 +504,8 @@ def checkdep_ps_distiller(s):
     return s
 
 
+@cbook.deprecated(
+    "3.3", alternative="matplotlib.testing.decorators.needs_usetex")
 def checkdep_usetex(s):
     if not s:
         return False

diff --git a/lib/matplotlib/testing/decorators.py b/lib/matplotlib/testing/decorators.py
@@ -459,3 +459,28 @@ def backend_switcher(*args, **kwargs):
         return backend_switcher
 
     return switch_backend_decorator
+
+
+def needs_usetex(func):
+    """
+    Decorate *func* with `unittest.skipIf` to skip the test if usetex
+    dependencies are missing.
+    """
+    has_tex = shutil.which("tex")
+    try:
+        mpl._get_executable_info("dvipng")
+    except FileNotFoundError:
+        has_dvipng = False
+    else:
+        has_dvipng = True
+    try:
+        mpl._get_executable_info("gs")
+    except FileNotFoundError:
+        has_gs = False
+    else:
+        has_gs = True
+    return (
+        unittest.skipIf(not has_tex, "usetex requires TeX.")(
+            unittest.skipIf(not has_dvipng, "usetex requires dvipng.")(
+                unittest.skipIf(not has_gs, "usetex requires ghostscript.")(
+                    func))))
diff --git a/lib/matplotlib/tests/test_backend_pdf.py b/lib/matplotlib/tests/test_backend_pdf.py
@@ -10,12 +10,7 @@
 from matplotlib import dviread, pyplot as plt, checkdep_usetex, rcParams
 from matplotlib.backends.backend_pdf import PdfPages
 from matplotlib.testing.compare import compare_images
-from matplotlib.testing.decorators import image_comparison
-
-
-needs_usetex = pytest.mark.skipif(
-    not checkdep_usetex(True),
-    reason="This test needs a TeX installation")
+from matplotlib.testing.decorators import image_comparison, needs_usetex
 
 
 @image_comparison(['pdf_use14corefonts.pdf'])

diff --git a/lib/matplotlib/tests/test_backend_ps.py b/lib/matplotlib/tests/test_backend_ps.py
@@ -7,15 +7,12 @@
 import matplotlib as mpl
 import matplotlib.pyplot as plt
 from matplotlib import cbook, patheffects
-from matplotlib.testing.decorators import image_comparison
+from matplotlib.testing.decorators import image_comparison, needs_usetex
 
 
 needs_ghostscript = pytest.mark.skipif(
     "eps" not in mpl.testing.compare.converter,
     reason="This test needs a ghostscript installation")
-needs_usetex = pytest.mark.skipif(
-    not mpl.checkdep_usetex(True),
-    reason="This test needs a TeX installation")
 
 
 # This tests tends to hit a TeX cache lock on AppVeyor.
@@ -26,11 +23,11 @@
     pytest.param('ps', False, {'ps.usedistiller': 'ghostscript'},
                  marks=needs_ghostscript),
     pytest.param('ps', False, {'text.usetex': True},
-                 marks=[needs_ghostscript, needs_usetex]),
+                 marks=needs_usetex),
     ('eps', False, {}),
     ('eps', True, {'ps.useafm': True}),
     pytest.param('eps', False, {'text.usetex': True},
-                 marks=[needs_ghostscript, needs_usetex]),
+                 marks=needs_usetex),
 ], ids=[
     'ps',
     'ps with distiller',
@@ -75,7 +72,6 @@ def test_patheffects():
 
 
 @needs_usetex
-@needs_ghostscript
 def tes
E29B
t_tilde_in_tempfilename(tmpdir):
     # Tilde ~ in the tempdir path (e.g. TMPDIR, TMP or TEMP on windows
     # when the username is very long and windows uses a short name) breaks

diff --git a/lib/matplotlib/tests/test_backend_svg.py b/lib/matplotlib/tests/test_backend_svg.py
@@ -10,12 +10,7 @@
 from matplotlib import dviread
 from matplotlib.figure import Figure
 import matplotlib.pyplot as plt
-from matplotlib.testing.decorators import image_comparison
-
-
-needs_usetex = pytest.mark.skipif(
-    not mpl.checkdep_usetex(True),
-    reason="This test needs a TeX installation")
+from matplotlib.testing.decorators import image_comparison, needs_usetex
 
 
 def test_visibility():

diff --git a/lib/matplotlib/tests/test_text.py b/lib/matplotlib/tests/test_text.py
@@ -9,12 +9,7 @@
 from matplotlib.backend_bases import MouseEvent
 import matplotlib.patches as mpatches
 import matplotlib.pyplot as plt
-from matplotlib.testing.decorators import check_figures_equal, image_comparison
-
-
-needs_usetex = pytest.mark.skipif(
-    not matplotlib.checkdep_usetex(True),
-    reason="This test needs a TeX installation")
+from matplotlib.testing.decorators import image_comparison, needs_usetex
 
 
 @image_comparison(['font_styles'])

diff --git a/lib/matplotlib/tests/test_usetex.py b/lib/matplotlib/tests/test_usetex.py
@@ -2,17 +2,12 @@
 import platform
 
 import matplotlib as mpl
-from matplotlib.testing.decorators import check_figures_equal, image_comparison
+from matplotlib.testing.decorators import (
+    check_figures_equal, image_comparison, needs_usetex)
 import matplotlib.pyplot as plt
 
 
-@pytest.fixture(autouse=True)  # All tests in this module use usetex.
-def usetex():
-    if not mpl.checkdep_usetex(True):
-        pytest.skip('Missing TeX of Ghostscript or dvipng')
-    mpl.rcParams['text.usetex'] = True
-
-
+@needs_usetex
 @image_comparison(baseline_images=['test_usetex'],
                   extensions=['pdf', 'png'],
                   tol={'aarch64': 2.868}.get(platform.machine(), 0.3))
@@ -25,12 +20,13 @@ def test_usetex():
             # \sqrt and \frac draw horizontal rules, \mathrm changes the font
             r'\LaTeX\ $\left[\int\limits_e^{2e}'
             r'\sqrt\frac{\log^3 x}{x}\,\mathrm{d}x \right\}$',
-            fontsize=24)
+            usetex=True, fontsize=24)
     ax.set_xticks([])
     ax.set_yticks([])
 
 
+@needs_usetex
 @check_figures_equal()
 def test_unicode_minus(fig_test, fig_ref):
-    fig_test.text(.5, .5, "$-$")
-    fig_ref.text(.5, .5, "\N{MINUS SIGN}")
+    fig_test.text(.5, .5, "$-$", usetex=True)
+    fig_ref.text(.5, .5, "\N{MINUS SIGN}", usetex=True)