assertRaises with context should replace context.exception with context.value

[graingert]

input

with self.assertRaises(Exception) as ctx:
    sut()

self.assertIn("msg", str(ctx.exception))

expected output

with pytest.raises(Exception) as ctx:
    sut()

assert "msg" in str(ctx.value)

[graingert]

or maybe you could cheat and output

with pytest.raises(Exception) as ctx:
    sut()

ctx.exception = ctx.value # TODO: replace all uses of ctx.exception with ctx.value
assert "msg" in str(ctx.exception)

[htgoebel]

This would required static code analysis. I considert this as "won't fix", but will keep it open for the case someone else is eager to pick it up.

[graingert]

Might be worth updating pytest to provide a .exception property alias

[graingert]

@htgoebel I believe this is the smallest code change to fix this issue: pytest-dev/pytest#5541

[graingert]

unittest2pytest/README.rst

Lines 78 to 83 in 2c32cd6

	Note: if your tests use the context managers ``with self.assertRaises`` or
	``with self.assertWarns``, they will be transformed to ``pytest.raises`` or
	``pytest.warns`` appropriately, but because the semantics are different, any
	use of the output value from the context managers (e.g. the ``x`` in
	``with pytest.raises(ValueError) as x:``) will be wrong and will require
	manual adjustment after the fact.

should probably be updated for when pytest-dev/pytest#5541 lands

[jaraco]

I encountered this issue today. Did you consider emitting a warning when this condition is encountered?