internal/zstd: use dynamic path resolution for xxhsum in FuzzXXHash

Updates #64000

Change-Id: I71fb80128d7e2a1f82322cbf04f74db01dcc631b
GitHub-Last-Rev: 7413594
GitHub-Pull-Request: #64003
Reviewed-on: https://go-review.googlesource.com/c/go/+/539938
Run-TryBot: Jes Cok <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>
Reviewed-by: Heschi Kreinick <[email protected]>

Author: callthingsoff

src/internal/zstd/xxhash_test.go

@@ -67,10 +67,16 @@ func TestLargeXXHash(t *testing.T) {
 	}
 }
 
-func FuzzXXHash(f *testing.F) {
-	if _, err := os.Stat("/usr/bin/xxhsum"); err != nil {
-		f.Skip("skipping because /usr/bin/xxhsum does not exist")
+func findXxhsum(t testing.TB) string {
+	xxhsum, err := exec.LookPath("xxhsum")
+	if err != nil {
+		t.Skip("skipping because xxhsum not found")
 	}
+	return xxhsum
+}
+
+func FuzzXXHash(f *testing.F) {
+	xxhsum := findXxhsum(f)
 
 	for _, test := range xxHashTests {
 		f.Add([]byte(test.data))
@@ -84,7 +90,7 @@ func FuzzXXHash(f *testing.F) {
 	f.Add(bigData(f))
 
 	f.Fuzz(func(t *testing.T, b []byte) {
-		cmd := exec.Command("/usr/bin/xxhsum", "-H64")
+		cmd := exec.Command(xxhsum, "-H64")
 		cmd.Stdin = bytes.NewReader(b)
 		var hhsumHash bytes.Buffer
 		cmd.Stdout = &hhsumHash