Fixed incorrect return value for mocked function (#6080)

Signed-off-by: Alex Le <[email protected]>

Author: alexqyle

pkg/compactor/compactor_test.go

@@ -1083,7 +1083,7 @@ func TestCompactor_ShouldSkipOutOrOrderBlocks(t *testing.T) {
 	cfg.SkipBlocksWithOutOfOrderChunksEnabled = true
 	c, tsdbCompac, tsdbPlanner, _, registry := prepare(t, cfg, bucketClient, nil)
 
-	tsdbCompac.On("CompactWithBlockPopulator", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return(b1, nil)
+	tsdbCompac.On("CompactWithBlockPopulator", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return([]ulid.ULID{b1}, nil)
 
 	tsdbPlanner.On("Plan", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return([]*metadata.Meta{
 		{
@@ -1986,7 +1986,7 @@ func TestCompactor_ShouldNotTreatInterruptionsAsErrors(t *testing.T) {
 	c, tsdbCompactor, tsdbPlanner, logs, registry := prepare(t, prepareConfig(), bucketClient, nil)
 
 	ctx, cancel := context.WithCancel(context.Background())
-	tsdbCompactor.On("CompactWithBlockPopulator", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return(ulid.ULID{}, context.Canceled).Run(func(args mock.Arguments) {
+	tsdbCompactor.On("CompactWithBlockPopulator", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return([]ulid.ULID{}, context.Canceled).Run(func(args mock.Arguments) {
 		cancel()
 	})
 	tsdbPlanner.On("Plan", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return([]*metadata.Meta{