Errors monkey-patching a class method using super()

[timabbott]

mypy throws:

/home/tabbott/foo.py: note: In function "foo":
/home/tabbott/foo.py:10: error: "super" used outside class
/home/tabbott/foo.py: note: At top level:
/home/tabbott/foo.py:13: error: Cannot assign to a method

with the following code monkey-patching a class with inheritance:

class Base(object):
    def test(self):
        return self.val

class Test(Base):
    val = "yay"

def foo(self):
    print(super(Test, self).test())

Test.test = foo

x = Test()
x.test()

Example real code with the issue is here:
https://github.com/zulip/zulip/blob/master/zerver/lib/test_helpers.py#L104

I think we could fix the super() issue by allowing super inside a non-class method when it's first argument is self (could imagine having an annotation tag along the lines of SelfType that auto-any uses for such a function?); a similar approach might work for the other one too (you can only assign functions with a SelfType tag to class methods?)

[msullivan]

We don't really try to support monkey patching at all