Merge pull request matplotlib#21005 from anntzer/rdmt

Test the rcParams deprecation machinery.

Author: jklymak

lib/matplotlib/tests/test_rcparams.py

@@ -508,3 +508,39 @@ def test_backend_fallback_headful(tmpdir):
     # The actual backend will depend on what's installed, but at least tkagg is
     # present.
     assert backend.strip().lower() != "agg"
+
+
+def test_deprecation(monkeypatch):
+    monkeypatch.setitem(
+        mpl._deprecated_map, "patch.linewidth",
+        ("0.0", "axes.linewidth", lambda old: 2 * old, lambda new: new / 2))
+    with pytest.warns(_api.MatplotlibDeprecationWarning):
+        assert mpl.rcParams["patch.linewidth"] \
+            == mpl.rcParams["axes.linewidth"] / 2
+    with pytest.warns(_api.MatplotlibDeprecationWarning):
+        mpl.rcParams["patch.linewidth"] = 1
+    assert mpl.rcParams["axes.linewidth"] == 2
+
+    monkeypatch.setitem(
+        mpl._deprecated_ignore_map, "patch.edgecolor",
+        ("0.0", "axes.edgecolor"))
+    with pytest.warns(_api.MatplotlibDeprecationWarning):
+        assert mpl.rcParams["patch.edgecolor"] \
+            == mpl.rcParams["axes.edgecolor"]
+    with pytest.warns(_api.MatplotlibDeprecationWarning):
+        mpl.rcParams["patch.edgecolor"] = "#abcd"
+    assert mpl.rcParams["axes.edgecolor"] != "#abcd"
+
+    monkeypatch.setitem(
+        mpl._deprecated_ignore_map, "patch.force_edgecolor",
+        ("0.0", None))
+    with pytest.warns(_api.MatplotlibDeprecationWarning):
+        assert mpl.rcParams["patch.force_edgecolor"] is None
+
+    monkeypatch.setitem(
+        mpl._deprecated_remain_as_none, "svg.hashsalt",
+        ("0.0",))
+    with pytest.warns(_api.MatplotlibDeprecationWarning):
+        mpl.rcParams["svg.hashsalt"] = "foobar"
+    assert mpl.rcParams["svg.hashsalt"] == "foobar"  # Doesn't warn.
+    mpl.rcParams["svg.hashsalt"] = None  # Doesn't warn.