Fragile tests relying on exact messaging of lintr output

[MichaelChirico]

What happened?

These two tests break under the current development version of R which is in the process of being released to CRAN:

logrx/tests/testthat/test-get.R

Lines 181 to 189 in f6c24f8

	expected <- paste0(
	"Line 6 [library_call_linter] Move all library calls to the ",
	"top of the script.\n\nLine 8 [undesirable_operator_linter] Operator ",
	"`<<-` is undesirable. It\nassigns outside the current environment in a ",
	"way that can be hard to reason\nabout. Prefer fully-encapsulated ",
	"functions wherever possible, or, if\nnecessary, assign to a specific ",
	"environment with assign(). Recall that you\ncan create an environment ",
	"at the desired scope with new.env()."
	)

logrx/tests/testthat/test-writer.R

Lines 199 to 209 in f6c24f8

	"Line 3 [undesirable_operator_linter] Operator `<<-` is undesirable.",
	" It\nassigns outside the current environment in a way that can be hard",
	" to reason\nabout. Prefer fully-encapsulated functions wherever possible,",
	" or, if\nnecessary, assign to a specific environment with assign(). ",
	"Recall that you\ncan create an environment at the desired scope with",
	" new.env().\n\nLine 4 [undesirable_operator_linter] Operator `<<-` is",
	" undesirable. It\nassigns outside the current environment in a way that",
	" can be hard to reason\nabout. Prefer fully-encapsulated functions",
	" wherever possible, or, if\nnecessary, assign to a specific environment",
	" with assign(). Recall that you\ncan create an environment at the",
	" desired scope with new.env()."

In general, I try and avoid relying on fragile things like "the exact wording of an error message produced by an upstream package".

For example, in {data.table}, we have this list of messages/message factories for test outputs that come directly from {base} R:

https://github.com/Rdatatable/data.table/blob/c29e313dac1de8b959f5e3438c33c0d00873be05/inst/tests/tests.Rraw#L176-L201

I will submit a quick-fix PR shortly, but it's worth thinking through a more robust way to structure these tests going forward.

Session Information

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Reproducible Example

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