TST: get coverage information out of isolated tk tests

tacaswell · tacaswell · commit ee7d467bc309 · 2022-01-13T15:02:25.000-05:00
diff --git a/lib/matplotlib/tests/test_backend_tk.py b/lib/matplotlib/tests/test_backend_tk.py
@@ -4,10 +4,11 @@
 import platform
 import re
 import subprocess
-import sys
 
 import pytest
 
+from matplotlib.testing import subprocess_run_helper
+
 _test_timeout = 60  # A reasonably safe value for slower architectures.
 
 
@@ -20,9 +21,7 @@ def _isolated_tk_test(success_count, func=None):
     in a subprocess. See GH#18261
 
     The decorated function must be fully self-contained, and thus perform
-    all the imports it needs.  Because its source is extracted and run by
-    itself, coverage will consider it as not being run, so it should be marked
-    with ``# pragma: no cover``
+    all the imports it needs.
     """
 
     if func is None:
@@ -34,14 +33,10 @@ def _isolated_tk_test(success_count, func=None):
     @functools.wraps(func)
     def test_func():
         try:
-            proc = subprocess.run(
-                [sys.executable, "-c", f"{source}\n{func.__name__}()"],
-                env={**os.environ, "MPLBACKEND": "TkAgg"},
-                timeout=_test_timeout,
-                stdout=subprocess.PIPE,
-                stderr=subprocess.PIPE,
-                check=True,
-                universal_newlines=True,
+            proc = subprocess_run_helper(
+                __name__, func, timeout=_test_timeout,
+                MPLBACKEND="TkAgg",
+                MPL_TEST_ESCAPE_HATCH="1"
             )
         except subprocess.TimeoutExpired:
             pytest.fail("Subprocess timed out")
@@ -55,13 +50,14 @@ def test_func():
             assert not [line for line in proc.stderr.splitlines()
                         if "OpenGL" not in line]
             assert proc.stdout.count("success") == success_count
-
-    return test_func
+    if "MPL_TEST_ESCAPE_HATCH" in os.environ:
+        return func
+    else:
+        return test_func
 
 
-@pytest.mark.backend('TkAgg', skip_on_importerror=True)
 @_isolated_tk_test(success_count=6)  # len(bad_boxes)
-def test_blit():  # pragma: no cover
+def test_blit():
     import matplotlib.pyplot as plt
     import numpy as np
     import matplotlib.backends.backend_tkagg  # noqa
@@ -88,9 +84,8 @@ def test_blit():  # pragma: no cover
             print("success")
 
 
-@pytest.mark.backend('TkAgg', skip_on_importerror=True)
 @_isolated_tk_test(success_count=1)
-def test_figuremanager_preserves_host_mainloop():  # pragma: no cover
+def test_figuremanager_preserves_host_mainloop():
     import tkinter
     import matplotlib.pyplot as plt
     success = []
@@ -116,10 +111,9 @@ def legitimate_quit():
 @pytest.mark.skipif(platform.python_implementation() != 'CPython',
                     reason='PyPy does not support Tkinter threading: '
                            'https://foss.heptapod.net/pypy/pypy/-/issues/1929')
-@pytest.mark.backend('TkAgg', skip_on_importerror=True)
 @pytest.mark.flaky(reruns=3)
 @_isolated_tk_test(success_count=1)
-def test_figuremanager_cleans_own_mainloop():  # pragma: no cover
+def test_figuremanager_cleans_own_mainloop():
     import tkinter
     import time
     import matplotlib.pyplot as plt
@@ -144,10 +138,9 @@ def target():
     thread.join()
 
 
-@pytest.mark.backend('TkAgg', skip_on_importerror=True)
 @pytest.mark.flaky(reruns=3)
 @_isolated_tk_test(success_count=0)
-def test_never_update():  # pragma: no cover
+def test_never_update():
     import tkinter
     del tkinter.Misc.update
     del tkinter.Misc.update_idletasks
@@ -171,9 +164,8 @@ def test_never_update():  # pragma: no cover
     # checks them.
 
 
-@pytest.mark.backend('TkAgg', skip_on_importerror=True)
 @_isolated_tk_test(success_count=2)
-def test_missing_back_button():  # pragma: no cover
+def test_missing_back_button():
     import matplotlib.pyplot as plt
     from matplotlib.backends.backend_tkagg import NavigationToolbar2Tk
 
