diff --git a/src/com/android/launcher3/Launcher.java b/src/com/android/launcher3/Launcher.java
index 8249887d9c..696c3089ab 100644
--- a/src/com/android/launcher3/Launcher.java
+++ b/src/com/android/launcher3/Launcher.java
@@ -1930,7 +1930,7 @@ public class Launcher extends StatefulActivity<LauncherState> implements Launche
 
     @Override
     public boolean dispatchKeyEvent(KeyEvent event) {
-        TestLogging.recordEvent(TestProtocol.SEQUENCE_MAIN, "Key event", event);
+        TestLogging.recordKeyEvent(TestProtocol.SEQUENCE_MAIN, "Key event", event);
         return (event.getKeyCode() == KeyEvent.KEYCODE_HOME) || super.dispatchKeyEvent(event);
     }
 
diff --git a/src/com/android/launcher3/testing/TestInformationHandler.java b/src/com/android/launcher3/testing/TestInformationHandler.java
index bc5129d8cf..6f61c0e766 100644
--- a/src/com/android/launcher3/testing/TestInformationHandler.java
+++ b/src/com/android/launcher3/testing/TestInformationHandler.java
@@ -130,13 +130,18 @@ public class TestInformationHandler implements ResourceBasedOverride {
 
             case TestProtocol.REQUEST_IS_TWO_PANELS:
                 response.putBoolean(TestProtocol.TEST_INFO_RESPONSE_FIELD,
-                    mDeviceProfile.isTwoPanels);
+                        mDeviceProfile.isTwoPanels);
                 return response;
 
             case TestProtocol.REQUEST_SET_FORCE_PAUSE_TIMEOUT:
                 TestProtocol.sForcePauseTimeout = Long.parseLong(arg);
                 return response;
 
+            case TestProtocol.REQUEST_GET_HAD_NONTEST_EVENTS:
+                response.putBoolean(
+                        TestProtocol.TEST_INFO_RESPONSE_FIELD, TestLogging.sHadEventsNotFromTest);
+                return response;
+
             default:
                 return null;
         }
diff --git a/src/com/android/launcher3/testing/TestLogging.java b/src/com/android/launcher3/testing/TestLogging.java
index 51e081972f..6cdd3ca6cf 100644
--- a/src/com/android/launcher3/testing/TestLogging.java
+++ b/src/com/android/launcher3/testing/TestLogging.java
@@ -17,6 +17,7 @@
 package com.android.launcher3.testing;
 
 import android.util.Log;
+import android.view.KeyEvent;
 import android.view.MotionEvent;
 
 import com.android.launcher3.Utilities;
@@ -25,6 +26,7 @@ import java.util.function.BiConsumer;
 
 public final class TestLogging {
     private static BiConsumer<String, String> sEventConsumer;
+    public static boolean sHadEventsNotFromTest;
 
     private static void recordEventSlow(String sequence, String event) {
         Log.d(TestProtocol.TAPL_EVENTS_TAG, sequence + " / " + event);
@@ -46,9 +48,17 @@ public final class TestLogging {
         }
     }
 
+    public static void recordKeyEvent(String sequence, String message, KeyEvent event) {
+        if (Utilities.IS_RUNNING_IN_TEST_HARNESS) {
+            recordEventSlow(sequence, message + ": " + event);
+            if (event.getDeviceId() != -1) sHadEventsNotFromTest = true;
+        }
+    }
+
     public static void recordMotionEvent(String sequence, String message, MotionEvent event) {
         if (Utilities.IS_RUNNING_IN_TEST_HARNESS && event.getAction() != MotionEvent.ACTION_MOVE) {
             recordEventSlow(sequence, message + ": " + event);
+            if (event.getDeviceId() != -1) sHadEventsNotFromTest = true;
         }
     }
 
diff --git a/src/com/android/launcher3/testing/TestProtocol.java b/src/com/android/launcher3/testing/TestProtocol.java
index d73c4b43a6..7d8f4797ce 100644
--- a/src/com/android/launcher3/testing/TestProtocol.java
+++ b/src/com/android/launcher3/testing/TestProtocol.java
@@ -93,6 +93,7 @@ public final class TestProtocol {
     public static final String REQUEST_RECENT_TASKS_LIST = "recent-tasks-list";
     public static final String REQUEST_START_EVENT_LOGGING = "start-event-logging";
     public static final String REQUEST_GET_TEST_EVENTS = "get-test-events";
+    public static final String REQUEST_GET_HAD_NONTEST_EVENTS = "get-had-nontest-events";
     public static final String REQUEST_STOP_EVENT_LOGGING = "stop-event-logging";
     public static final String REQUEST_CLEAR_DATA = "clear-data";
     public static final String REQUEST_IS_TABLET = "is-tablet";
diff --git a/tests/src/com/android/launcher3/util/rule/FailureWatcher.java b/tests/src/com/android/launcher3/util/rule/FailureWatcher.java
index 5fbf847ec6..60529a43c4 100644
--- a/tests/src/com/android/launcher3/util/rule/FailureWatcher.java
+++ b/tests/src/com/android/launcher3/util/rule/FailureWatcher.java
@@ -13,6 +13,7 @@ import com.android.launcher3.ui.AbstractLauncherUiTest;
 
 import org.junit.rules.TestWatcher;
 import org.junit.runner.Description;
+import org.junit.runners.model.Statement;
 
 import java.io.File;
 import java.io.FileOutputStream;
@@ -37,6 +38,26 @@ public class FailureWatcher extends TestWatcher {
         AbstractLauncherUiTest.checkDetectedLeaks(mLauncher);
     }
 
+    @Override
+    public Statement apply(Statement base, Description description) {
+        return new Statement() {
+            @Override
+            public void evaluate() throws Throwable {
+                try {
+                    base.evaluate();
+                } finally {
+                    if (mLauncher.hadNontestEvents()) {
+                        throw new AssertionError(
+                                "Launcher received events not sent by the test. This may mean "
+                                        + "that the touch screen of the lab device has sent false"
+                                        + " events. See the logcat for TaplEvents tag and look "
+                                        + "for events with deviceId != -1");
+                    }
+                }
+            }
+        };
+    }
+
     @Override
     protected void failed(Throwable e, Description description) {
         onError(mDevice, description, e);
diff --git a/tests/tapl/com/android/launcher3/tapl/LauncherInstrumentation.java b/tests/tapl/com/android/launcher3/tapl/LauncherInstrumentation.java
index abcc7788e2..c2930f19a1 100644
--- a/tests/tapl/com/android/launcher3/tapl/LauncherInstrumentation.java
+++ b/tests/tapl/com/android/launcher3/tapl/LauncherInstrumentation.java
@@ -306,6 +306,11 @@ public final class LauncherInstrumentation {
         getTestInfo(TestProtocol.REQUEST_SET_FORCE_PAUSE_TIMEOUT, Long.toString(timeout));
     }
 
+    public boolean hadNontestEvents() {
+        return getTestInfo(TestProtocol.REQUEST_GET_HAD_NONTEST_EVENTS)
+                .getBoolean(TestProtocol.TEST_INFO_RESPONSE_FIELD);
+    }
+
     void setActiveContainer(VisibleContainer container) {
         sActiveContainer = new WeakReference<>(container);
     }