diff --git a/src/com/android/settings/accessibility/ToggleScreenMagnificationPreferenceFragment.java b/src/com/android/settings/accessibility/ToggleScreenMagnificationPreferenceFragment.java
index 2de2cb727ee..ac4a961a6f1 100644
--- a/src/com/android/settings/accessibility/ToggleScreenMagnificationPreferenceFragment.java
+++ b/src/com/android/settings/accessibility/ToggleScreenMagnificationPreferenceFragment.java
@@ -46,6 +46,7 @@ import androidx.preference.PreferenceCategory;
 import androidx.preference.PreferenceScreen;
 import androidx.preference.PreferenceViewHolder;
 
+import com.android.internal.annotations.VisibleForTesting;
 import com.android.settings.R;
 import com.android.settings.accessibility.AccessibilityUtil.UserShortcutType;
 
@@ -509,7 +510,8 @@ public class ToggleScreenMagnificationPreferenceFragment extends
         int EDIT_SHORTCUT = 3;
     }
 
-    private static void optInAllMagnificationValuesToSettings(Context context, int shortcutTypes) {
+    @VisibleForTesting
+    static void optInAllMagnificationValuesToSettings(Context context, int shortcutTypes) {
         if ((shortcutTypes & UserShortcutType.SOFTWARE) == UserShortcutType.SOFTWARE) {
             optInMagnificationValueToSettings(context, UserShortcutType.SOFTWARE);
         }
@@ -532,7 +534,7 @@ public class ToggleScreenMagnificationPreferenceFragment extends
         }
 
         final StringJoiner joiner = new StringJoiner(String.valueOf(COMPONENT_NAME_SEPARATOR));
-        if (TextUtils.isEmpty(targetString)) {
+        if (!TextUtils.isEmpty(targetString)) {
             joiner.add(targetString);
         }
         joiner.add(MAGNIFICATION_CONTROLLER_NAME);
@@ -540,7 +542,8 @@ public class ToggleScreenMagnificationPreferenceFragment extends
         Settings.Secure.putString(context.getContentResolver(), targetKey, joiner.toString());
     }
 
-    private static void optOutAllMagnificationValuesFromSettings(Context context,
+    @VisibleForTesting
+    static void optOutAllMagnificationValuesFromSettings(Context context,
             int shortcutTypes) {
         if ((shortcutTypes & UserShortcutType.SOFTWARE) == UserShortcutType.SOFTWARE) {
             optOutMagnificationValueFromSettings(context, UserShortcutType.SOFTWARE);
@@ -576,7 +579,8 @@ public class ToggleScreenMagnificationPreferenceFragment extends
         Settings.Secure.putString(context.getContentResolver(), targetKey, joiner.toString());
     }
 
-    private static boolean hasMagnificationValuesInSettings(Context context, int shortcutTypes) {
+    @VisibleForTesting
+    static boolean hasMagnificationValuesInSettings(Context context, int shortcutTypes) {
         boolean exist = false;
 
         if ((shortcutTypes & UserShortcutType.SOFTWARE) == UserShortcutType.SOFTWARE) {
diff --git a/tests/robotests/src/com/android/settings/accessibility/ToggleScreenMagnificationPreferenceFragmentTest.java b/tests/robotests/src/com/android/settings/accessibility/ToggleScreenMagnificationPreferenceFragmentTest.java
new file mode 100644
index 00000000000..3a2aa4c36e1
--- /dev/null
+++ b/tests/robotests/src/com/android/settings/accessibility/ToggleScreenMagnificationPreferenceFragmentTest.java
@@ -0,0 +1,130 @@
+/*
+ * Copyright (C) 2020 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.accessibility;
+
+import static com.android.settings.accessibility.AccessibilityUtil.UserShortcutType;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import android.content.ComponentName;
+import android.content.Context;
+import android.provider.Settings;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.RuntimeEnvironment;
+
+@RunWith(RobolectricTestRunner.class)
+public class ToggleScreenMagnificationPreferenceFragmentTest {
+
+    private static final String DUMMY_PACKAGE_NAME = "com.dummy.example";
+    private static final String DUMMY_CLASS_NAME = DUMMY_PACKAGE_NAME + ".dummy_a11y_service";
+    private static final ComponentName DUMMY_COMPONENT_NAME = new ComponentName(DUMMY_PACKAGE_NAME,
+            DUMMY_CLASS_NAME);
+    private static final String SOFTWARE_SHORTCUT_KEY =
+            Settings.Secure.ACCESSIBILITY_BUTTON_TARGET_COMPONENT;
+    private static final String HARDWARE_SHORTCUT_KEY =
+            Settings.Secure.ACCESSIBILITY_SHORTCUT_TARGET_SERVICE;
+    private static final String TRIPLETAP_SHORTCUT_KEY =
+            Settings.Secure.ACCESSIBILITY_DISPLAY_MAGNIFICATION_ENABLED;
+    private static final String MAGNIFICATION_CONTROLLER_NAME =
+            "com.android.server.accessibility.MagnificationController";
+
+    private Context mContext;
+
+    @Before
+    public void setUp() {
+        mContext = RuntimeEnvironment.application;
+    }
+
+    @Test
+    public void hasValueInSettings_putValue_hasValue() {
+        putStringIntoSettings(TRIPLETAP_SHORTCUT_KEY, MAGNIFICATION_CONTROLLER_NAME);
+
+        assertThat(ToggleScreenMagnificationPreferenceFragment.hasMagnificationValuesInSettings(
+                mContext, UserShortcutType.TRIPLETAP)).isTrue();
+    }
+
+    @Test
+    public void optInAllValuesToSettings_optInValue_haveMatchString() {
+        int shortcutTypes = UserShortcutType.SOFTWARE | UserShortcutType.TRIPLETAP;
+
+        ToggleScreenMagnificationPreferenceFragment.optInAllMagnificationValuesToSettings(mContext,
+                shortcutTypes);
+
+        assertThat(getStringFromSettings(SOFTWARE_SHORTCUT_KEY)).isEqualTo(
+                MAGNIFICATION_CONTROLLER_NAME);
+        assertThat(getStringFromSettings(TRIPLETAP_SHORTCUT_KEY)).isEqualTo(
+                MAGNIFICATION_CONTROLLER_NAME);
+
+    }
+
+    @Test
+    public void optInAllValuesToSettings_existOtherValue_optInValue_haveMatchString() {
+        putStringIntoSettings(SOFTWARE_SHORTCUT_KEY, DUMMY_COMPONENT_NAME.flattenToString());
+
+        ToggleScreenMagnificationPreferenceFragment.optInAllMagnificationValuesToSettings(mContext,
+                UserShortcutType.SOFTWARE);
+
+        assertThat(getStringFromSettings(SOFTWARE_SHORTCUT_KEY)).isEqualTo(
+                DUMMY_COMPONENT_NAME.flattenToString() + ":" + MAGNIFICATION_CONTROLLER_NAME);
+
+    }
+
+    @Test
+    public void optOutAllValuesToSettings_optOutValue_emptyString() {
+        putStringIntoSettings(SOFTWARE_SHORTCUT_KEY, MAGNIFICATION_CONTROLLER_NAME);
+        putStringIntoSettings(HARDWARE_SHORTCUT_KEY, MAGNIFICATION_CONTROLLER_NAME);
+        putStringIntoSettings(TRIPLETAP_SHORTCUT_KEY, MAGNIFICATION_CONTROLLER_NAME);
+        int shortcutTypes =
+                UserShortcutType.SOFTWARE | UserShortcutType.HARDWARE | UserShortcutType.TRIPLETAP;
+
+        ToggleScreenMagnificationPreferenceFragment.optOutAllMagnificationValuesFromSettings(
+                mContext, shortcutTypes);
+
+        assertThat(getStringFromSettings(SOFTWARE_SHORTCUT_KEY)).isEmpty();
+        assertThat(getStringFromSettings(HARDWARE_SHORTCUT_KEY)).isEmpty();
+        assertThat(getStringFromSettings(TRIPLETAP_SHORTCUT_KEY)).isEmpty();
+    }
+
+    @Test
+    public void optOutValueFromSettings_existOtherValue_optOutValue_haveMatchString() {
+        putStringIntoSettings(SOFTWARE_SHORTCUT_KEY,
+                DUMMY_COMPONENT_NAME.flattenToString() + ":" + MAGNIFICATION_CONTROLLER_NAME);
+        putStringIntoSettings(HARDWARE_SHORTCUT_KEY,
+                DUMMY_COMPONENT_NAME.flattenToString() + ":" + MAGNIFICATION_CONTROLLER_NAME);
+        int shortcutTypes = UserShortcutType.SOFTWARE | UserShortcutType.HARDWARE;
+
+        ToggleScreenMagnificationPreferenceFragment.optOutAllMagnificationValuesFromSettings(
+                mContext, shortcutTypes);
+
+        assertThat(getStringFromSettings(SOFTWARE_SHORTCUT_KEY)).isEqualTo(
+                DUMMY_COMPONENT_NAME.flattenToString());
+        assertThat(getStringFromSettings(HARDWARE_SHORTCUT_KEY)).isEqualTo(
+                DUMMY_COMPONENT_NAME.flattenToString());
+    }
+
+    private void putStringIntoSettings(String key, String componentName) {
+        Settings.Secure.putString(mContext.getContentResolver(), key, componentName);
+    }
+
+    private String getStringFromSettings(String key) {
+        return Settings.Secure.getString(mContext.getContentResolver(), key);
+    }
+}