Embed: In case KVStoreHash verification fails, close the backend.

In case of failed verification, the server used to keep opened backend
(so the file was locked on OS level).

client/pkg/testutil/leak.go

@@ -110,8 +110,12 @@ func BeforeTest(t TB) {
 // It will detect common goroutine leaks, retrying in case there are goroutines
 // not synchronously torn down, and fail the test if any goroutines are stuck.
 func AfterTest(t TB) {
-	if err := CheckAfterTest(1 * time.Second); err != nil {
-		t.Errorf("Test %v", err)
+	// If test-failed the leaked goroutines list is hidding the real
+	// source of problem.
+	if !t.Failed() {
+		if err := CheckAfterTest(1 * time.Second); err != nil {
+			t.Errorf("Test %v", err)
+		}
 	}
 }
 

client/pkg/testutil/testutil.go

@@ -53,8 +53,9 @@ func MustNewURL(t *testing.T, s string) *url.URL {
 func FatalStack(t *testing.T, s string) {
 	stackTrace := make([]byte, 1024*1024)
 	n := runtime.Stack(stackTrace, true)
+	t.Errorf("---> Test failed: %s", s)
 	t.Error(string(stackTrace[:n]))
-	t.Fatalf(s)
+	t.Fatal(s)
 }
 
 // ConditionFunc returns true when a condition is met.