not_shows_message and not_prints_text

[wush978]

I think it might be useful for not_shows_message or not_prints_text which is similar to shows_message and prints_text except that the test is fail instead of pass.

For example, I need to test if executing an external program does not produces warning message.

[wush978]

Hi,

I have created R functions not_shows_message and not_matches in https://github.com/wush978/test_that/commit/560ecb2123a9264a6f7c3967fb0535f0a065f0f8

Since I'm still not familiar with test_that, the proposed features might be redundant or inappropriate. Please give me some instructions or feedback about this issue.

Thanks.

[hadley]

I agree that these tests are needed and currently missing (see also #62), but I'd really like some global way of doing this, rather than having to create a negated version of every single expectation.

[richfitz]

Would it be possible to have a not() function (as in https://gist.github.com/richfitz/5056365), and have each expectation function prepare a string for success and for failure. The not() function would just toggle the value of passed and select the alternative string.

There aren't so many expectations that this seems like a huge change, doesn't proliferate expectations, and would be backward compatible with user-defined expectations if it is possible to come up with a string that indicates that it was expected that test would fail.

[hadley]

@richfitz Yeah, I was just thinking about that too. I think it's a solid approach.

[hadley]

Please see 1b1987b and b475797. If this looks good for the expect_that form, I'll add negated helpers.

[muschellij2]

Is this still the case since not() is becoming deprecated?

Or should it be something like testthat::expect_failure(expect_warning(expr))