Merge pull request #13935 from anntzer/switch_backend_warn

tacaswell · web-flow · commit 0c4f13ae4b34 · 2019-04-14T21:30:53.000-04:00
Deprecate the useless switch_backend_warn parameter to matplotlib.test.
diff --git a/doc/api/next_api_changes/2019-04-12-AL.rst b/doc/api/next_api_changes/2019-04-12-AL.rst
@@ -0,0 +1,5 @@
+Deprecations
+````````````
+
+The ``switch_backend_warn`` parameter to ``matplotlib.test`` has no effect and
+is deprecated.
diff --git a/lib/matplotlib/__init__.py b/lib/matplotlib/__init__.py
@@ -1262,7 +1262,6 @@ def use(backend, warn=False, force=True):
         If True and not *force*, warn that the call will have no effect if
         this is called after pyplot has been imported and a backend is set up.
 
-
     force : bool, optional, default: True
         If True, attempt to switch the backend.   An ImportError is raised if
         an interactive backend is selected, but another interactive
@@ -1281,20 +1280,17 @@ def use(backend, warn=False, force=True):
     elif 'matplotlib.pyplot' in sys.modules:
         # pyplot has already been imported (which triggered backend selection)
         # and the requested backend is different from the current one.
-
-        # If we are going to force the switch, never warn, else, if warn
-        # is True, then direct users to `plt.switch_backend`
-        if (not force) and warn:
-            cbook._warn_external(
-                "matplotlib.pyplot has already been imported, "
-                "this call will have no effect.")
-
-        # if we are going to force switching the backend, pull in
-        # `switch_backend` from pyplot.  This will only happen if
-        # pyplot is already imported.
         if force:
+            # if we are going to force switching the backend, pull in
+            # `switch_backend` from pyplot (which is already imported).
             from matplotlib.pyplot import switch_backend
             switch_backend(name)
+        elif warn:
+            # Only if we are not going to force the switch *and* warn is True,
+            # then direct users to `plt.switch_backend`.
+            cbook._warn_external(
+                "matplotlib.pyplot has already been imported, "
+                "this call will have no effect.")
     else:
         # Finally if pyplot is not imported update both rcParams and
         # rcDefaults so restoring the defaults later with rcdefaults
@@ -1385,6 +1381,7 @@ def _init_tests():
         raise
 
 
+@cbook._delete_parameter("3.2", "switch_backend_warn")
 def test(verbosity=None, coverage=False, switch_backend_warn=True,
          recursionlimit=0, **kwargs):
     """Run the matplotlib test suite."""
@@ -1426,7 +1423,7 @@ def test(verbosity=None, coverage=False, switch_backend_warn=True,
         retcode = pytest.main(args, **kwargs)
     finally:
         if old_backend.lower() != 'agg':
-            use(old_backend, warn=switch_backend_warn)
+            use(old_backend)
         if recursionlimit:
             sys.setrecursionlimit(old_recursionlimit)
 
diff --git a/tests.py b/tests.py
@@ -45,6 +45,5 @@
 
     print('Python byte-compilation optimization level:', sys.flags.optimize)
 
-    retcode = test(argv=extra_args, switch_backend_warn=False,
-                   recursionlimit=args.recursionlimit)
+    retcode = test(argv=extra_args, recursionlimit=args.recursionlimit)
     sys.exit(retcode)
