diff --git a/quickstep/src/com/android/quickstep/util/MotionPauseDetector.java b/quickstep/src/com/android/quickstep/util/MotionPauseDetector.java
index ac2534e..65be624 100644
--- a/quickstep/src/com/android/quickstep/util/MotionPauseDetector.java
+++ b/quickstep/src/com/android/quickstep/util/MotionPauseDetector.java
@@ -17,6 +17,7 @@
 
 import android.content.Context;
 import android.content.res.Resources;
+import android.util.Log;
 import android.view.MotionEvent;
 import android.view.VelocityTracker;
 
@@ -85,7 +86,12 @@
         mSpeedSomewhatFast = res.getDimension(R.dimen.motion_pause_detector_speed_somewhat_fast);
         mSpeedFast = res.getDimension(R.dimen.motion_pause_detector_speed_fast);
         mForcePauseTimeout = new Alarm();
-        mForcePauseTimeout.setOnAlarmListener(alarm -> updatePaused(true /* isPaused */));
+        mForcePauseTimeout.setOnAlarmListener(alarm -> {
+            if (TestProtocol.sDebugTracing) {
+                Log.d(TestProtocol.MOTION_PAUSE_TIMEOUT, "onAlarm");
+            }
+            updatePaused(true /* isPaused */);
+        });
         mMakePauseHarderToTrigger = makePauseHarderToTrigger;
         mVelocityProvider = new SystemVelocityProvider(axis);
     }
@@ -119,9 +125,13 @@
      * @param pointerIndex Index for the pointer being tracked in the motion event
      */
     public void addPosition(MotionEvent ev, int pointerIndex) {
-        mForcePauseTimeout.setAlarm(TestProtocol.sForcePauseTimeout != null
+        long timeoutMs = TestProtocol.sForcePauseTimeout != null
                 ? TestProtocol.sForcePauseTimeout
-                : mMakePauseHarderToTrigger ? HARDER_TRIGGER_TIMEOUT : FORCE_PAUSE_TIMEOUT);
+                : mMakePauseHarderToTrigger ? HARDER_TRIGGER_TIMEOUT : FORCE_PAUSE_TIMEOUT;
+        if (TestProtocol.sDebugTracing) {
+            Log.d(TestProtocol.MOTION_PAUSE_TIMEOUT, "setAlarm: " + timeoutMs);
+        }
+        mForcePauseTimeout.setAlarm(timeoutMs);
         float newVelocity = mVelocityProvider.addMotionEvent(ev, ev.getPointerId(pointerIndex));
         if (mPreviousVelocity != null) {
             checkMotionPaused(newVelocity, mPreviousVelocity, ev.getEventTime());
@@ -162,6 +172,9 @@
                 }
             }
         }
+        if (TestProtocol.sDebugTracing) {
+            Log.d(TestProtocol.MOTION_PAUSE_TIMEOUT, "checkMotionPaused: " + isPaused);
+        }
         updatePaused(isPaused);
     }
 
diff --git a/src/com/android/launcher3/Launcher.java b/src/com/android/launcher3/Launcher.java
index 8249887..696c308 100644
--- a/src/com/android/launcher3/Launcher.java
+++ b/src/com/android/launcher3/Launcher.java
@@ -1930,7 +1930,7 @@
 
     @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 bc5129d..6f61c0e 100644
--- a/src/com/android/launcher3/testing/TestInformationHandler.java
+++ b/src/com/android/launcher3/testing/TestInformationHandler.java
@@ -130,13 +130,18 @@
 
             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 51e0819..6cdd3ca 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 @@
 
 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 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 d73c4b4..82bb111 100644
--- a/src/com/android/launcher3/testing/TestProtocol.java
+++ b/src/com/android/launcher3/testing/TestProtocol.java
@@ -93,6 +93,7 @@
     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";
@@ -116,4 +117,5 @@
     public static final String WORK_PROFILE_REMOVED = "b/159671700";
     public static final String FALLBACK_ACTIVITY_NO_SET = "b/181019015";
     public static final String THIRD_PARTY_LAUNCHER_NOT_SET = "b/187080582";
+    public static final String MOTION_PAUSE_TIMEOUT = "b/194114179";
 }
diff --git a/tests/src/com/android/launcher3/util/rule/FailureWatcher.java b/tests/src/com/android/launcher3/util/rule/FailureWatcher.java
index 5fbf847..60529a4 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 org.junit.rules.TestWatcher;
 import org.junit.runner.Description;
+import org.junit.runners.model.Statement;
 
 import java.io.File;
 import java.io.FileOutputStream;
@@ -38,6 +39,26 @@
     }
 
     @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 abcc778..c2930f1 100644
--- a/tests/tapl/com/android/launcher3/tapl/LauncherInstrumentation.java
+++ b/tests/tapl/com/android/launcher3/tapl/LauncherInstrumentation.java
@@ -306,6 +306,11 @@
         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);
     }