diff --git a/services/core/java/com/android/server/wm/DisplayPolicy.java b/services/core/java/com/android/server/wm/DisplayPolicy.java
index 3df1bfc5e331e..cc7e8b1bc8613 100644
--- a/services/core/java/com/android/server/wm/DisplayPolicy.java
+++ b/services/core/java/com/android/server/wm/DisplayPolicy.java
@@ -2291,7 +2291,8 @@ public class DisplayPolicy {
         return width;
     }
 
-    private int getNavigationBarHeight(int rotation, int uiMode) {
+    @VisibleForTesting
+    int getNavigationBarHeight(int rotation, int uiMode) {
         if (INSETS_LAYOUT_GENERALIZATION) {
             if (mNavigationBar == null) {
                 return 0;
diff --git a/services/tests/wmtests/src/com/android/server/wm/TestDisplayContent.java b/services/tests/wmtests/src/com/android/server/wm/TestDisplayContent.java
index ce2d748599316..0d919d109587a 100644
--- a/services/tests/wmtests/src/com/android/server/wm/TestDisplayContent.java
+++ b/services/tests/wmtests/src/com/android/server/wm/TestDisplayContent.java
@@ -20,6 +20,7 @@ import static android.app.WindowConfiguration.WINDOWING_MODE_FULLSCREEN;
 import static android.view.DisplayAdjustments.DEFAULT_DISPLAY_ADJUSTMENTS;
 
 import static com.android.dx.mockito.inline.extended.ExtendedMockito.anyBoolean;
+import static com.android.dx.mockito.inline.extended.ExtendedMockito.anyInt;
 import static com.android.dx.mockito.inline.extended.ExtendedMockito.doAnswer;
 import static com.android.dx.mockito.inline.extended.ExtendedMockito.doNothing;
 import static com.android.dx.mockito.inline.extended.ExtendedMockito.doReturn;
@@ -153,6 +154,7 @@ class TestDisplayContent extends DisplayContent {
             if (mSystemDecorations) {
                 doReturn(true).when(newDisplay).supportsSystemDecorations();
                 doReturn(true).when(displayPolicy).hasNavigationBar();
+                doReturn(20).when(displayPolicy).getNavigationBarHeight(anyInt(), anyInt());
             } else {
                 doReturn(false).when(displayPolicy).hasNavigationBar();
                 doReturn(false).when(displayPolicy).hasStatusBar();