Add function to assert that an object is an instance of a specific type

tests/unit/_utils/test_assert_that_is_instance.py

@@ -0,0 +1,29 @@
+from src.jcloud_docsgen.utils import assert_that_is_instance
+import pytest
+import types
+
+class TestType: ...
+TestType.__name__ = 'NOT TestType'
+
+@pytest.mark.parametrize('obj,class_or_tuple', [
+    (1, int),
+    (1, (int,)),
+    (1, str | int),
+    (1, int | str | list),
+    (TestType(), TestType),
+    (None, types.NoneType),
+])
+def test_assert_that_is_instance(obj, class_or_tuple):
+    assert_that_is_instance(obj, class_or_tuple)
+
+@pytest.mark.parametrize('obj,class_or_tuple,expected_exception_msg', [
+    (1, str, 'expected \'str\', got \'int\''),
+    (1, (str,), 'expected \'str\', got \'int\''),
+    (1, str | float, 'expected either \'str\' or \'float\', got \'int\''),
+    (1, str | float | list, 'expected either \'str\', \'float\' or \'list\', got \'int\''),
+    (1, TestType, 'expected \'NOT TestType\', got \'int\''),
+])
+def test_assert_that_is_instance_exceptions(obj, class_or_tuple, expected_exception_msg):
+    with pytest.raises(TypeError) as exc_info:
+        assert_that_is_instance(obj, class_or_tuple)
+    assert str(exc_info.value) == expected_exception_msg