Fix ZRangeArgs Start/Stop ordering for BYSCORE REV in GetWorkflowInstances

backend/redis/diagnostics.go

@@ -36,8 +36,8 @@ func (rb *redisBackend) GetWorkflowInstances(ctx context.Context, afterInstanceI
 
 	result, err := rb.rdb.ZRangeArgs(ctx, redis.ZRangeArgs{
 		Key:     rb.keys.instancesByCreation(),
-		Stop:    stop,
-		Start:   "-inf",
+		Start:   stop,
+		Stop:    "-inf",
 		ByScore: true,
 		Rev:     true,
 		Count:   int64(count),

backend/redis/diagnostics_test.go

@@ -42,3 +42,75 @@ func Test_Diag_GetWorkflowInstances(t *testing.T) {
 	require.Len(t, instances, 1)
 	require.Equal(t, "ex1", instances[0].Instance.InstanceID)
 }
+
+func Test_Diag_GetWorkflowInstances_Ordering(t *testing.T) {
+	if testing.Short() {
+		t.Skip()
+	}
+
+	rclient := getClient()
+	setup := getCreateBackend(rclient)
+
+	b := setup()
+
+	t.Cleanup(func() {
+		require.NoError(t, b.Close())
+	})
+
+	bd := b.(diag.Backend)
+	c := client.New(b)
+	ctx := context.Background()
+
+	for _, id := range []string{"inst-a", "inst-b", "inst-c"} {
+		_, err := c.CreateWorkflowInstance(ctx, client.WorkflowInstanceOptions{InstanceID: id}, "some-workflow")
+		require.NoError(t, err)
+	}
+
+	// Results should be newest-first (Rev: true).
+	instances, err := bd.GetWorkflowInstances(ctx, "", "", 10)
+	require.NoError(t, err)
+	require.Len(t, instances, 3)
+	require.Equal(t, "inst-c", instances[0].Instance.InstanceID)
+	require.Equal(t, "inst-a", instances[2].Instance.InstanceID)
+}
+
+func Test_Diag_GetWorkflowInstances_Pagination(t *testing.T) {
+	if testing.Short() {
+		t.Skip()
+	}
+
+	rclient := getClient()
+	setup := getCreateBackend(rclient)
+
+	b := setup()
+
+	t.Cleanup(func() {
+		require.NoError(t, b.Close())
+	})
+
+	bd := b.(diag.Backend)
+	c := client.New(b)
+	ctx := context.Background()
+
+	for _, id := range []string{"inst-1", "inst-2", "inst-3", "inst-4"} {
+		_, err := c.CreateWorkflowInstance(ctx, client.WorkflowInstanceOptions{InstanceID: id}, "some-workflow")
+		require.NoError(t, err)
+	}
+
+	// First page: newest 2.
+	page1, err := bd.GetWorkflowInstances(ctx, "", "", 2)
+	require.NoError(t, err)
+	require.Len(t, page1, 2)
+
+	// Second page: continue after last item of page 1.
+	last := page1[len(page1)-1]
+	page2, err := bd.GetWorkflowInstances(ctx, last.Instance.InstanceID, last.Instance.ExecutionID, 2)
+	require.NoError(t, err)
+	require.Len(t, page2, 2)
+
+	// No overlap between pages.
+	page1IDs := map[string]bool{page1[0].Instance.InstanceID: true, page1[1].Instance.InstanceID: true}
+	for _, inst := range page2 {
+		require.False(t, page1IDs[inst.Instance.InstanceID], "duplicate instance across pages: %s", inst.Instance.InstanceID)
+	}
+}