Change ready_at to first_ready_at and make a unit test for it

src/registrar/migrations/0057_domain_deleted_at_domain_first_ready_at.py

@@ -1,4 +1,4 @@
-# Generated by Django 4.2.7 on 2023-12-21 17:12
+# Generated by Django 4.2.7 on 2023-12-21 19:28
 
 from django.db import migrations, models
 
@@ -16,7 +16,7 @@ class Migration(migrations.Migration):
         ),
         migrations.AddField(
             model_name="domain",
-            name="ready_at",
+            name="first_ready_at",
             field=models.DateField(
                 editable=False, help_text="The last time this domain moved into the READY state", null=True
             ),

src/registrar/models/domain.py

@@ -967,7 +967,7 @@ class Domain(TimeStampedModel, DomainHelper):
         help_text="Deleted at date",
     )
 
-    ready_at = DateField(
+    first_ready_at = DateField(
         null=True,
         editable=False,
         help_text="The last time this domain moved into the READY state",
@@ -1336,7 +1336,11 @@ class Domain(TimeStampedModel, DomainHelper):
         """
         logger.info("Changing to ready state")
         logger.info("able to transition to ready state")
-        self.ready_at = timezone.now()
+        # if self.first_ready_at is not None, this means that his
+        # domain wasr READY, then not READY, then is READY again.
+        # We do not want to overwrite first_ready_at.
+        if self.first_ready_at is None:
+            self.first_ready_at = timezone.now()
 
     @transition(
         field="state",

src/registrar/tests/test_models_domain.py

@@ -385,6 +385,34 @@ class TestDomainStatuses(MockEppLib):
         """Domain 'revert_client_hold' method causes the registry to change statuses"""
         raise
 
+    def test_first_ready_at(self):
+        """
+        first_ready_at is set when a domain is first transitioned to READY. It does not get overwritten
+        in case the domain gets out of and back into READY.
+        """
+        domain, _ = Domain.objects.get_or_create(name="pig-knuckles.gov", state=Domain.State.DNS_NEEDED)
+        self.assertEqual(domain.first_ready_at, None)
+
+        domain.ready()
+
+        # check that status is READY
+        self.assertTrue(domain.is_active())
+        self.assertNotEqual(domain.first_ready_at, None)
+
+        # Capture the value of first_ready_at
+        first_ready_at = domain.first_ready_at
+
+        # change domain status
+        domain.dns_needed()
+        self.assertFalse(domain.is_active())
+
+        # change  back to READY
+        domain.ready()
+        self.assertTrue(domain.is_active())
+
+        # assert that the value of first_ready_at has not changed
+        self.assertEqual(domain.first_ready_at, first_ready_at)
+
     def tearDown(self) -> None:
         PublicContact.objects.all().delete()
         Domain.objects.all().delete()
@@ -1112,7 +1140,7 @@ class TestRegistrantNameservers(MockEppLib):
             Then `commands.CreateHost` and `commands.UpdateDomain` is sent
                 to the registry
             And `domain.is_active` returns False
-            And domain.ready_at is null
+            And domain.first_ready_at is null
         """
 
         # set 1 nameserver
@@ -1139,7 +1167,7 @@ class TestRegistrantNameservers(MockEppLib):
         # as you have less than 2 nameservers
         self.assertFalse(self.domain.is_active())
 
-        self.assertEqual(self.domain.ready_at, None)
+        self.assertEqual(self.domain.first_ready_at, None)
 
     def test_user_adds_two_nameservers(self):
         """
@@ -1149,7 +1177,7 @@ class TestRegistrantNameservers(MockEppLib):
             Then `commands.CreateHost` and `commands.UpdateDomain` is sent
                 to the registry
             And `domain.is_active` returns True
-            And domain.ready_at is not null
+            And domain.first_ready_at is not null
         """
 
         # set 2 nameservers
@@ -1180,7 +1208,7 @@ class TestRegistrantNameservers(MockEppLib):
         self.assertEqual(4, self.mockedSendFunction.call_count)
         # check that status is READY
         self.assertTrue(self.domain.is_active())
-        self.assertNotEqual(self.domain.ready_at, None)
+        self.assertNotEqual(self.domain.first_ready_at, None)
 
     def test_user_adds_too_many_nameservers(self):
         """