Don't observe Modes changes if MODES_UI is disabled

The ZenModesLinkPreferenceController is present in the Notifications and Sound screens, and although isAvailable() is false when MODES_UI is not enabled, it was still registering the listener for Settings changes, and calling updateState().

Thus, Settings would (likely) crash if Zen settings change while the user is in one of those screens, due to not finding the manual rule.

Fixes: 360498255
Test: atest ZenSettingsObserverTest
Flag: android.app.modes_ui
Change-Id: I7741809fd0028aace6ac58992be965701e64a2e3

src/com/android/settings/notification/modes/ZenSettingsObserver.java

@@ -16,6 +16,7 @@
 
 package com.android.settings.notification.modes;
 
+import android.app.Flags;
 import android.content.Context;
 import android.database.ContentObserver;
 import android.net.Uri;
@@ -42,13 +43,17 @@ class ZenSettingsObserver extends ContentObserver {
     }
 
     void register() {
-        mContext.getContentResolver().registerContentObserver(ZEN_MODE_URI, false, this);
-        mContext.getContentResolver().registerContentObserver(ZEN_MODE_CONFIG_ETAG_URI, false,
-                this);
+        if (Flags.modesApi() && Flags.modesUi()) {
+            mContext.getContentResolver().registerContentObserver(ZEN_MODE_URI, false, this);
+            mContext.getContentResolver().registerContentObserver(ZEN_MODE_CONFIG_ETAG_URI, false,
+                    this);
+        }
     }
 
     void unregister() {
-        mContext.getContentResolver().unregisterContentObserver(this);
+        if (Flags.modesApi() && Flags.modesUi()) {
+            mContext.getContentResolver().unregisterContentObserver(this);
+        }
     }
 
     void setOnChangeListener(@Nullable Runnable callback) {

tests/robotests/src/com/android/settings/notification/modes/ZenSettingsObserverTest.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.notification.modes;
+
+import static android.provider.Settings.Global.ZEN_MODE_CONFIG_ETAG;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.robolectric.Shadows.shadowOf;
+
+import android.app.Flags;
+import android.content.Context;
+import android.database.ContentObserver;
+import android.net.Uri;
+import android.platform.test.annotations.DisableFlags;
+import android.platform.test.annotations.EnableFlags;
+import android.platform.test.flag.junit.SetFlagsRule;
+import android.provider.Settings;
+
+import androidx.test.core.app.ApplicationProvider;
+
+import com.google.common.collect.ImmutableList;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.shadows.ShadowLooper;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+@RunWith(RobolectricTestRunner.class)
+public class ZenSettingsObserverTest {
+
+    @Rule
+    public final SetFlagsRule mSetFlagsRule = new SetFlagsRule();
+
+    private static final Uri SETTINGS_URI = Settings.Global.getUriFor(
+            ZEN_MODE_CONFIG_ETAG);
+
+    private Context mContext;
+    private ZenSettingsObserver mObserver;
+
+    @Before
+    public void setUp() {
+        mContext = ApplicationProvider.getApplicationContext();
+        mObserver = new ZenSettingsObserver(mContext);
+    }
+
+    @Test
+    @EnableFlags(Flags.FLAG_MODES_UI)
+    public void register_withFlagEnabled_registersAndCallsBack() {
+        AtomicInteger someValue = new AtomicInteger();
+        mObserver.setOnChangeListener(someValue::incrementAndGet);
+        assertThat(getSettingsContentObservers()).isEmpty();
+
+        mObserver.register();
+        assertThat(getSettingsContentObservers()).hasSize(1);
+
+        getSettingsContentObservers().forEach(o -> o.dispatchChange(false, SETTINGS_URI));
+        ShadowLooper.idleMainLooper();
+        assertThat(someValue.get()).isEqualTo(1);
+
+        mObserver.unregister();
+        assertThat(getSettingsContentObservers()).isEmpty();
+    }
+
+    @Test
+    @DisableFlags(Flags.FLAG_MODES_UI)
+    public void register_withFlagDisabled_doesNotRegister() {
+        mObserver.register();
+        assertThat(getSettingsContentObservers()).isEmpty();
+        mObserver.unregister();
+        assertThat(getSettingsContentObservers()).isEmpty();
+    }
+
+    private ImmutableList<ContentObserver> getSettingsContentObservers() {
+        return ImmutableList.copyOf(
+                shadowOf(mContext.getContentResolver())
+                        .getContentObservers(SETTINGS_URI));
+    }
+}