Module cargo_test_support::compare

Routines for comparing and diffing output.

Patterns

Many of these functions support special markup to assist with comparing text that may vary or is otherwise uninteresting for the test at hand. The supported patterns are:

• [..] is a wildcard that matches 0 or more characters on the same line (similar to .* in a regex). It is non-greedy.
• [EXE] optionally adds .exe on Windows (empty string on other platforms).
• [ROOT] is the path to the test directory’s root.
• [CWD] is the working directory of the process that was run.
• There is a wide range of substitutions (such as [COMPILING] or [WARNING]) to match cargo’s “status” output and allows you to ignore the alignment. See the source of substitute_macros for a complete list of substitutions.
• [DIRTY-MSVC] (only when the line starts with it) would be replaced by [DIRTY] when cfg(target_env = "msvc") or the line will be ignored otherwise. Tests that work around issue 7358 can use this to avoid duplicating the with_stderr call like: if cfg!(target_env = "msvc") {e.with_stderr("...[DIRTY]...");} else {e.with_stderr("...");}.

Normalization

In addition to the patterns described above, the strings are normalized in such a way to avoid unwanted differences. The normalizations are:

• Raw tab characters are converted to the string <tab>. This is helpful so that raw tabs do not need to be written in the expected string, and to avoid confusion of tabs vs spaces.
• Backslashes are converted to forward slashes to deal with Windows paths. This helps so that all tests can be written assuming forward slashes. Other heuristics are applied to try to ensure Windows-style paths aren’t a problem.
• Carriage returns are removed, which can help when running on Windows.

Functions

• assert_e2e
  Assertion policy for functional end-to-end tests
• assert_ui
  Assertion policy for UI tests