tests: Add tests for custom warnings

Author: JDBetteridge

tests/test_warnings.py

@@ -0,0 +1,76 @@
+import pytest
+import warnings
+
+from devito.warnings import warn, DevitoWarning
+
+
+class NewWarning(UserWarning):
+    """
+    A custom warning class
+    """
+    pass
+
+
+@pytest.fixture
+def custom_warning():
+    # Instance of custom warning class
+    return NewWarning('** NEW ** A fun new kind of warning')
+
+
+class TestDevitoWarnings:
+    """
+    In all cases check that the `DevitoWarning` type of Warning is raised
+    __in all cases__, even if a custom type is provided
+    """
+    def test_raise(self):
+        with pytest.warns(DevitoWarning) as w:
+            warn('Let this be a warning to you')
+
+        assert len(w) == 1
+        assert 'DevitoWarning' in repr(w[0].message)
+        assert w[0].filename == __file__
+
+    def test_raise_from_user(self):
+        with pytest.warns(DevitoWarning) as w:
+            warn('Let this be another warning to you', UserWarning)
+
+        assert len(w) == 1
+        assert 'UserWarning:' in str(w[0].message)
+        assert w[0].filename == __file__
+
+    def test_raise_from_user_kw(self):
+        with pytest.warns(DevitoWarning) as w:
+            warn('Let this be another warning to you', category=UserWarning)
+
+        assert len(w) == 1
+        assert 'UserWarning:' in str(w[0].message)
+        assert w[0].filename == __file__
+
+    def test_raise_from_custom(self, custom_warning):
+        with pytest.warns(DevitoWarning) as w:
+            warn(custom_warning)
+
+        assert len(w) == 1
+        assert 'NewWarning:' in str(w[0].message)
+        assert w[0].filename == __file__
+
+
+class TestWarning:
+    """
+    Check that the custom DevitoWarning does not interfere with Python warnings
+    """
+    def test_raise(self):
+        with pytest.warns(UserWarning):
+            warnings.warn('Let this be a warning to you')
+
+    def test_raise_devito(self):
+        with pytest.warns(DevitoWarning):
+            warnings.warn('Let this be another warning to you', DevitoWarning)
+
+    def test_raise_devito_kw(self):
+        with pytest.warns(DevitoWarning):
+            warn('Let this be another warning to you', category=DevitoWarning)
+
+    def test_raise_from_custom(self, custom_warning):
+        with pytest.warns(NewWarning):
+            warnings.warn(custom_warning)