assertRaises-type tests should only contain a single statement

[Jelle Zijlstra]

Consider this code:

with pytest.raises(TypeError):
    1 + "x"
    "x" + 1

This will pass if only one of the two statements raises, which is probably not what the author wanted. Instead, each statement should be in its own pytest.raises context. (Real-world example: python/cpython#103880.)

We should show an error if an assertRaises-type context (pytest.raises, self.assertRaises, self.assertRaisesRegex) contains more than one top-level statement.

[Cooper Lees]

Yup - sure, This is definitely a bug that could hide failures. PR would be accepted.

I'd like to keep the scope to testing here tho to start with. This could open a can of worms if we look at context mangers/exception handling more broadly ...

[Alexey Nikitin]

Can be closed @cooperlees