Implement expect_all_equal() and friends

[hadley]

Fixes #1836. Fixes #2235. Closes #2240.

[claude]

Claude finished @hadley's task —— View job

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Code Review

• Review new expect_all_equal() implementation
• Check test coverage and snapshots
• Review modifications to expect-match.R
• Identify potential bugs or issues
• Provide minimal feedback

Analysis

The PR introduces expect_all_equal() - a function to test that all elements in a vector equal a single expected value. Implementation looks solid:

• Input validation is comprehensive (R/expect-all.R:5-13)
• Uses existing expect_waldo_equal_() infrastructure correctly
• Test coverage is good with edge cases and error scenarios
• Snapshots show appropriate error messages

The refactoring of show_text() in expect-match.R improves the API by making the labels parameter more generic.

LGTM.

[DavisVaughan]

Suggested change

	#' Do you expect every value in a vector to have this value?
	#' Does a vector have a constant value?

Just thinking out loud

[hadley]

Constant makes me think unchanging (over time)

[DavisVaughan]

Suggested change

	! Expected every element of `x` to equal TRUE.
	! Expected every element of `x` to equal `TRUE`.

??

[hadley]

FWIW that would be inconsistent with expect_equal().