Properly handle AutomatedBackupPolicy midnight start time (hours = 0) (#8337) (#15219)

* Properly handle ABP midnight (hours = 0)

* Add ExpectNonEmptyPlan to test

* Simplify custom flatten

Signed-off-by: Modular Magician <[email protected]>

Author: modular-magician

.changelog/8337.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+Fix automated backup policy handling of 0 start time (midnight)
+```

google/resource_alloydb_cluster_test.go

@@ -79,6 +79,7 @@ func TestAccAlloydbCluster_addAutomatedBackupPolicyAndInitialUser(t *testing.T)
 
 	context := map[string]interface{}{
 		"random_suffix": acctest.RandString(t, 10),
+		"hour":          23,
 	}
 
 	acctest.VcrTest(t, resource.TestCase{
@@ -119,6 +120,7 @@ func TestAccAlloydbCluster_deleteAutomatedBackupPolicyAndInitialUser(t *testing.
 
 	context := map[string]interface{}{
 		"random_suffix": acctest.RandString(t, 10),
+		"hour":          23,
 	}
 
 	acctest.VcrTest(t, resource.TestCase{
@@ -151,6 +153,37 @@ func TestAccAlloydbCluster_deleteAutomatedBackupPolicyAndInitialUser(t *testing.
 	})
 }
 
+// Test if automatedBackupPolicy properly handles a startTime of 0 (aka midnight). Calling terraform plan
+// after creating the cluster should not bring anything up.
+func TestAccAlloydbCluster_AutomatedBackupPolicyHandlesMidnight(t *testing.T) {
+	t.Parallel()
+
+	context := map[string]interface{}{
+		"random_suffix": acctest.RandString(t, 10),
+		"hour":          0,
+	}
+
+	acctest.VcrTest(t, resource.TestCase{
+		PreCheck:                 func() { acctest.AccTestPreCheck(t) },
+		ProtoV5ProviderFactories: acctest.ProtoV5ProviderFactories(t),
+		CheckDestroy:             testAccCheckAlloydbClusterDestroyProducer(t),
+		Steps: []resource.TestStep{
+			{
+				Config: testAccAlloydbCluster_withInitialUserAndAutomatedBackupPolicy(context),
+			},
+			{
+				ResourceName:            "google_alloydb_cluster.default",
+				ImportState:             true,
+				ImportStateVerify:       true,
+				ImportStateVerifyIgnore: []string{"initial_user", "cluster_id", "location"},
+			},
+			{
+				Config: testAccAlloydbCluster_alloydbClusterBasicExample(context),
+			},
+		},
+	})
+}
+
 func testAccAlloydbCluster_withInitialUserAndAutomatedBackupPolicy(context map[string]interface{}) string {
 	return acctest.Nprintf(`
 resource "google_alloydb_cluster" "default" {
@@ -172,7 +205,7 @@ resource "google_alloydb_cluster" "default" {
       days_of_week = ["MONDAY"]
 
       start_times {
-        hours   = 23
+        hours   = %{hour}
         minutes = 0
         seconds = 0
         nanos   = 0

google/services/alloydb/resource_alloydb_cluster.go

@@ -860,8 +860,8 @@ func flattenAlloydbClusterAutomatedBackupPolicyWeeklyScheduleStartTimes(v interf
 	for _, raw := range l {
 		original := raw.(map[string]interface{})
 		if len(original) < 1 {
-			// Do not include empty json objects coming back from the api
-			continue
+			// If no start times exist, that means we take backups at midnight. This is represented as 0's all around.
+			return append(transformed, map[string]interface{}{})
 		}
 		transformed = append(transformed, map[string]interface{}{
 			"hours":   flattenAlloydbClusterAutomatedBackupPolicyWeeklyScheduleStartTimesHours(original["hours"], d, config),
@@ -872,6 +872,7 @@ func flattenAlloydbClusterAutomatedBackupPolicyWeeklyScheduleStartTimes(v interf
 	}
 	return transformed
 }
+
 func flattenAlloydbClusterAutomatedBackupPolicyWeeklyScheduleStartTimesHours(v interface{}, d *schema.ResourceData, config *transport_tpg.Config) interface{} {
 	// Handles the string fixed64 format
 	if strVal, ok := v.(string); ok {