testenv.MustHaveExecPath(t, "bzr")
	testenv.MustHaveExecPath(t, "git")
	// TODO(jayconrod): add hg, svn, and fossil modules to testdata.
	// Could not find any for now.

	tests, err := readZipSumTests()
	if err != nil {
		t.Fatal(err)
	}

	if *modCacheDir != "" {
		cfg.BuildContext.GOPATH = *modCacheDir
	} else {
		tmpDir, err := os.MkdirTemp("", "TestZipSums")
		if err != nil {
			t.Fatal(err)