Add some tests for extending object lock duration (#3965)

Make sure that we can successfully update the object lock duration and run full maintenance without having to close and reopen the repo.

---

#### Does this PR need a docs update or release note?

- [ ] ✅ Yes, it's included
- [ ] 🕐 Yes, but in a later PR
- [x] ⛔ No

#### Type of change

- [ ] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [x] 🤖 Supportability/Tests
- [ ] 💻 CI/Deployment
- [ ] 🧹 Tech Debt/Cleanup

#### Issue(s)

* #3519

#### Test Plan

- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E

src/internal/kopia/wrapper_test.go

@@ -369,6 +369,25 @@ func checkRetentionParams(
 	expectExtend(t, params.ExtendObjectLocks, "extend object locks")
 }
 
+// mustReopen closes and reopens the connection that w uses. Assumes no other
+// structs besides w are holding a reference to the conn that w has.
+//
+//revive:disable-next-line:context-as-argument
+func mustReopen(t *testing.T, ctx context.Context, w *Wrapper) {
+	k := w.c
+
+	err := w.Close(ctx)
+	require.NoError(t, err, "closing wrapper: %v", clues.ToCore(err))
+
+	err = k.Close(ctx)
+	require.NoError(t, err, "closing conn: %v", clues.ToCore(err))
+
+	err = k.Connect(ctx, repository.Options{})
+	require.NoError(t, err, "reconnecting conn: %v", clues.ToCore(err))
+
+	w.c = k
+}
+
 type RetentionIntegrationSuite struct {
 	tester.Suite
 }
@@ -592,6 +611,91 @@ func (suite *RetentionIntegrationSuite) TestSetRetentionParameters_And_Maintenan
 		assert.False)
 }
 
+func (suite *RetentionIntegrationSuite) TestSetAndUpdateRetentionParameters_RunMaintenance() {
+	table := []struct {
+		name   string
+		reopen bool
+	}{
+		{
+			// Check that in the same connection we can create a repo, set and then
+			// update the retention period, and run full maintenance to extend object
+			// locks.
+			name: "SameConnection",
+		},
+		{
+			// Test that even if the retention configuration change is done from a
+			// different repo connection that we still can extend the object locking
+			// duration and run maintenance successfully.
+			name:   "ReopenToReconfigure",
+			reopen: true,
+		},
+	}
+
+	for _, test := range table {
+		suite.Run(test.name, func() {
+			t := suite.T()
+
+			ctx, flush := tester.NewContext(t)
+			defer flush()
+
+			k, err := openKopiaRepo(t, ctx)
+			require.NoError(t, err, clues.ToCore(err))
+
+			w := &Wrapper{k}
+
+			mOpts := repository.Maintenance{
+				Safety: repository.FullMaintenanceSafety,
+				Type:   repository.CompleteMaintenance,
+			}
+
+			// This will set common maintenance config parameters. There's some interplay
+			// between the maintenance schedule and retention period that we want to check
+			// below.
+			err = w.RepoMaintenance(ctx, mOpts)
+			require.NoError(t, err, clues.ToCore(err))
+
+			// Enable retention.
+			err = w.SetRetentionParameters(ctx, repository.Retention{
+				Mode:     ptr.To(repository.GovernanceRetention),
+				Duration: ptr.To(time.Hour * 48),
+				Extend:   ptr.To(true),
+			})
+			require.NoError(t, err, clues.ToCore(err))
+
+			checkRetentionParams(
+				t,
+				ctx,
+				k,
+				blob.Governance,
+				time.Hour*48,
+				assert.True)
+
+			if test.reopen {
+				mustReopen(t, ctx, w)
+			}
+
+			// Change retention duration without updating mode.
+			err = w.SetRetentionParameters(ctx, repository.Retention{
+				Duration: ptr.To(time.Hour * 96),
+			})
+			require.NoError(t, err, clues.ToCore(err))
+
+			checkRetentionParams(
+				t,
+				ctx,
+				k,
+				blob.Governance,
+				time.Hour*96,
+				assert.True)
+
+			// Run full maintenance again. This should extend object locks for things if
+			// they exist.
+			err = w.RepoMaintenance(ctx, mOpts)
+			require.NoError(t, err, clues.ToCore(err))
+		})
+	}
+}
+
 // ---------------
 // integration tests that use kopia and initialize a repo
 // ---------------