cmp_fast_path test improvements #507

Job	Run time
Code Coverage (macos-latest, macos)	2m 50s
cargo fmt --all -- --check	7s
cargo test (windows-latest)	4m 42s
GNU test suite	57s
cargo test (macOS-latest)	1m 29s
Code Coverage (ubuntu-latest, unix)	1m 52s
cargo clippy -- -D warnings (macOS-latest)	14s
cargo clippy -- -D warnings (windows-latest)	1m 7s
cargo check (ubuntu-latest)	28s
cargo test (ubuntu-latest)	31s
cargo check (macOS-latest)	13s
Code Coverage (windows-latest, windows)	7m 14s
cargo clippy -- -D warnings (ubuntu-latest)	12s
cargo check (windows-latest)	58s
	22m 54s

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