Add test cases

Author: JukkaL

mypy/test/data/check-ignore.test

@@ -28,3 +28,17 @@ x   # E: Name 'x' is not defined
 x = 1
 x = '' # type: ignore
 x = '' # E: Incompatible types in assignment (expression has type "str", variable has type "int")
+
+[case testIgnoreInvalidOverride]
+class A:
+    def f(self) -> int: pass
+class B(A):
+    def f(self) -> str: pass # type: ignore
+
+[case testIgnoreMissingModuleAttribute]
+import m
+m.x = object # type: ignore
+m.f() # type: ignore
+m.y # E: "module" has no attribute "y"
+[file m.py]
+[builtins fixtures/module.py]