Tests

fix variable expansion in error message #1765

Job	Run time
quick-test	4m 29s
cargo-mutants (0, cargo)	6m 36s
test (macOS-latest, stable)	7m 36s
cargo-mutants (1, cargo)	8m 4s
pr-mutants	0s
branch-mutants	0s
test (macOS-latest, nightly)	10m 15s
cargo-mutants (2, cargo)	7m 9s
cargo-mutants (3, cargo)	12m 7s
test (macOS-latest, 1.78)	5m 18s
tests-from-tarball (ubuntu-latest)	2m 19s
cargo-mutants (4, cargo)	9m 26s
test (ubuntu-latest, stable)	6m 37s
test (ubuntu-latest, nightly)	8m 15s
cargo-mutants (5, cargo)	10m 55s
test (ubuntu-latest, 1.78)	4m 56s
cargo-mutants (6, cargo)	8m 27s
test (windows-latest, stable)	11m 37s
cargo-mutants (7, cargo)	11m 55s
test (windows-latest, nightly)	15m 43s
test (windows-latest, 1.78)	8m 51s
cargo-mutants (8, cargo)	11m 43s
cargo-mutants (9, cargo)	7m 30s
	2h 59m 48s

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