Increase backend_registry test coverage

ianthomas23 · ianthomas23 · commit 987cdc42cf4d · 2024-04-26T12:06:28.000+01:00
diff --git a/lib/matplotlib/tests/test_backend_registry.py b/lib/matplotlib/tests/test_backend_registry.py
@@ -67,6 +67,25 @@ def test_list_builtin_with_filter(filter, expected):
     assert {*backends} == {*expected}
 
 
+def test_list_gui_frameworks():
+    frameworks = backend_registry.list_gui_frameworks()
+    assert not has_duplicates(frameworks)
+    # Compare using sets as order is not important
+    assert {*frameworks} == {
+        "gtk3", "gtk4", "osx", "qt", "qt5", "qt6", "tk", "wx",
+    }
+
+
+@pytest.mark.parametrize("backend, is_valid", [
+    ("agg", True),
+    ("QtAgg", True),
+    ("module://anything", True),
+    ("made-up-name", False),
+])
+def test_is_valid_backend(backend, is_valid):
+    assert backend_registry.is_valid_backend(backend) == is_valid
+
+
 def test_deprecated_rcsetup_attributes():
     match = "was deprecated in Matplotlib 3.9"
     with pytest.warns(mpl.MatplotlibDeprecationWarning, match=match):
@@ -119,3 +138,23 @@ def test_load_entry_points_only_if_needed(clear_backend_registry, backend):
     assert not backend_registry._loaded_entry_points
     backend_registry.list_all()  # Force load of entry points
     assert backend_registry._loaded_entry_points
+
+
+@pytest.mark.parametrize(
+    'gui_or_backend, expected_backend, expected_gui',
+    [
+        ('agg', 'agg', None),
+        ('qt', 'qtagg', 'qt'),
+        ('TkCairo', 'tkcairo', 'tk'),
+    ]
+)
+def test_resolve_gui_or_backend(gui_or_backend, expected_backend, expected_gui):
+    backend, gui = backend_registry.resolve_gui_or_backend(gui_or_backend)
+    assert backend == expected_backend
+    assert gui == expected_gui
+
+
+def test_resolve_gui_or_backend_invalid():
+    match = "is not a recognised GUI loop or backend name"
+    with pytest.raises(RuntimeError, match=match):
+        backend_registry.resolve_gui_or_backend('no-such-name')
