Attempting to reproduce an issue when generating code-coverage for a project that uses the crate prometheus-0.9
To reproduce (using nightly-2020-11-25):
$ rm *.prof*
$ cargo clean
$ RUSTFLAGS="-Z instrument-coverage" LLVM_PROFILE_FILE="cargo-%m.profraw" cargo +nightly-2020-11-25 test --tests
...
Running target/debug/deps/prometheus_code_cov-24bcfe5d001389f5
running 1 test
test tests::it_returns_1 ... ok
...
$ cargo +nightly-2020-11-25 profdata -- merge -sparse *.profraw -o out.profdata
$ cargo cov -- report --instr-profile=./out.profdata target/debug/deps/prometheus_code_cov-24bcfe5d001389f5
error: target/debug/deps/prometheus_code_cov-24bcfe5d001389f5: Failed to load coverage: Truncated coverage data
To generate code coverage, do one of the following:
- Change
prometheusinCargo.tomlto0.8 - Remove
use prometheus::Encoder;insrc/lib.rs:4 - Remove
tokio::spawn(start_server());insrc/lib.rs:13
Output when one of the above is changed:
$ rm *.prof*
$ cargo clean
$ RUSTFLAGS="-Z instrument-coverage" LLVM_PROFILE_FILE="cargo-%m.profraw" cargo +nightly-2020-11-25 test --tests
$ cargo +nightly-2020-11-25 profdata -- merge -sparse *.profraw -o out.profdata
$ cargo cov -- report --instr-profile=./out.profdata target/debug/deps/prometheus_code_cov-24bcfe5d001389f5
...
src/lib.rs 12 8 33.33% 6 2 66.67% 24 9 62.50%
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL 17839 17136 3.94% 2078 1765 15.06% 20773 19266 7.25%