Usage

As is stated in the cargo-difftests README, one could simply use cargo-difftests like so:

% # collect profiling data
% cargo difftests collect-profiling-data
% touch src/advanced_arithmetic.rs # change mtime
% cargo difftests analyze --dir target/tmp/difftests/tests/test_add
clean
% cargo difftests analyze --dir target/tmp/difftests/tests/test_mul
dirty
% cargo difftests analyze --dir target/tmp/difftests/tests/test_div
dirty
% cargo difftests collect-profiling-data --filter test_mul --exact
% cargo difftests analyze --dir target/tmp/difftests/tests/test_mul
clean
% cargo difftests analyze --dir target/tmp/difftests/tests/test_div
dirty
% cargo difftests collect-profiling-data --filter test_div --exact
% cargo difftests analyze --dir target/tmp/difftests/tests/test_div
clean

Recommended workflow

Initial profiling data collection

cargo difftests collect-profiling-data --compile-index --index-root=difftests-index-root --root=target/tmp/difftests

Analyze, rerun and collect new profiling data

CARGO_DIFFTESTS_EXTRA_ARGS='--compile-index,--index-root=difftests-index-root,--root=target/tmp/difftests' cargo difftests rerun-dirty-from-indexes --index-root=difftests-index-root

cargo difftests rerun-dirty-from-indexes is basically an alias for cargo difftests analyze-all-from-index --action=rerun-dirty; more information about analyze-all can be found in the analyze-all article.

The --compile-index tells cargo-difftests to compile indexes. You can optionally pass --and-clean next to --compile-index to have cargo-difftests clean up all the profiling data other than the index after it’s done running a test, to reduce the amount of required disk space.