Raise in cachedResult when result is not called

src/unittest_extensions/case.py

@@ -64,9 +64,13 @@ def result(self) -> Any:
     def cachedResult(self) -> Any:
         """
         Return the result of the last `subject` call.
-        Use this function if when you to assert different attributes of your
+        Use this function when you want to assert different attributes of your
         subject without executing it multiple times.
+
+        Raises `unittest_extensions.TestError` if subject has not been called.
         """
+        if not hasattr(self, "_subject_result"):
+            raise TestError("Cannot call 'cachedResult' before calling 'result'")
         return self._subject_result
 
     def assertResult(self, value):

src/unittest_extensions/tests/test_use_case.py

@@ -62,6 +62,11 @@ def test_missing_arg_raises(self):
             TestError, "Subject misses 1 required positional argument."
         )
 
+    @args({"a": 1, "b": 2})
+    def test_cachedResult_raises(self):
+        with self.assertRaises(TestError):
+            self.cachedResult()
+
 
 class TestAppend(TestCase):