misuse of pytest API in tests:

[rotu]

This error is showing up in CI:
https://ci.ros2.org/job/ci_linux/7643/testReport/rosidl_adapter.test/test_parse_message_string/test_parse_message_string/

AssertionError: assert 'foo' in '' + where '' = str()

thrown here:

rosidl/rosidl_adapter/test/test_parse_message_file.py

Lines 40 to 42 in b7d12f5

	with pytest.raises(ValueError) as e:
	parse_message_file('pkg', filename)
	assert 'foo' in str(e)

and a similar failure https://ci.ros2.org/job/ci_linux/7643/testReport/rosidl_adapter.test/test_parse_message_string/test_parse_message_string/ thrown here:

rosidl/rosidl_adapter/test/test_parse_message_string.py

Lines 71 to 73 in b7d12f5

	with pytest.raises(ValueError) as e:
	parse_message_string('pkg', 'Foo', 'bool FOO=1\nbool FOO=1')
	assert 'FOO' in str(e)

The issue is that when using with pytest.raises(...) as e, e contains an ExceptionInfo object, not the exception itself. This test should be corrected.

[rotu]

seems to be due to changing behavior of str() on ExceptionInfo objects in pytest 5: pytest-dev/pytest#5412

[rotu]

Fixed in #393