Cargo flaky-test

Tries to make a flaky Rust test fail or time out and dumps the trace of all threads to disk. Assumes lldb to be installed.

Install:

cargo install --git https://github.com/ggwpez/flaky-test

Example

Investigating the voter_persists_its_votes test of the sc-consensus-grandpa crate in the polkadot-sdk workspace:

RUST_LOG=info flaky-test \
	--manifest-path ../polkadot-sdk \
	-p sc-consensus-grandpa voter_persists_its_votes \
	--timeout 120 --batch 10 --reps 10

Shows us that it indeed fails. Otherwise increase the batch size. With >100 it should reliably fail:

Now you can take a look at the stacktrace file, or start a debugger and attach it to the printed PID. Traces look like this.
Attaching lldb can be done with lldb attach -p ....

License

GPLv3 only as per LICENSE.