Fix TestSilenceLimits tests

This commit fixes silence tests that relied on the maintenance
function running at a fixed 100ms interval. If the go runtime
that runs the maintenance is not scheduled with 150ms then the
test will fail.

Signed-off-by: George Robinson <[email protected]>

silence/silence_test.go

@@ -465,12 +465,8 @@ func TestSilenceLimits(t *testing.T) {
 			MaxSilences:        1,
 			MaxPerSilenceBytes: 2 << 11, // 4KB
 		},
-		Retention: 100 * time.Millisecond,
 	})
 	require.NoError(t, err)
-	stopCh := make(chan struct{})
-	defer close(stopCh)
-	go s.Maintenance(100*time.Millisecond, "", stopCh, nil)
 
 	// Insert sil1 should succeed without error.
 	sil1 := &pb.Silence{
@@ -493,10 +489,13 @@ func TestSilenceLimits(t *testing.T) {
 	require.EqualError(t, err, "exceeded maximum number of silences: 1 (limit: 1)")
 	require.Equal(t, "", id2)
 
-	// Expire sil1 and wait for the maintenance to finish.
-	// This should allow sil2 to be inserted.
+	// Expire sil1 and run the GC. This should allow sil2 to be
+	// inserted.
 	require.NoError(t, s.Expire(id1))
-	time.Sleep(150 * time.Millisecond)
+	n, err := s.GC()
+	require.NoError(t, err)
+	require.Equal(t, 1, n)
+
 	id2, err = s.Set(sil2)
 	require.NoError(t, err)
 	require.NotEqual(t, "", id2)
@@ -507,7 +506,9 @@ func TestSilenceLimits(t *testing.T) {
 
 	// Expire sil2.
 	require.NoError(t, s.Expire(id2))
-	time.Sleep(150 * time.Millisecond)
+	n, err = s.GC()
+	require.NoError(t, err)
+	require.Equal(t, 1, n)
 
 	// Insert sil3 should fail because it exceeds maximum size.
 	sil3 := &pb.Silence{