diff --git a/services/core/java/com/android/server/biometrics/sensors/face/aidl/Sensor.java b/services/core/java/com/android/server/biometrics/sensors/face/aidl/Sensor.java
index a204c6c..90aa4ad 100644
--- a/services/core/java/com/android/server/biometrics/sensors/face/aidl/Sensor.java
+++ b/services/core/java/com/android/server/biometrics/sensors/face/aidl/Sensor.java
@@ -436,13 +436,7 @@
         mScheduler = new BiometricScheduler(tag, null /* gestureAvailabilityDispatcher */);
         mLockoutCache = new LockoutCache();
         mAuthenticatorIds = new HashMap<>();
-        mLazySession = () -> {
-            if (mTestHalEnabled) {
-                return new TestSession(mCurrentSession.mHalSessionCallback);
-            } else {
-                return mCurrentSession != null ? mCurrentSession.mSession : null;
-            }
-        };
+        mLazySession = () -> mCurrentSession != null ? mCurrentSession.mSession : null;
     }
 
     @NonNull HalClientMonitor.LazyDaemon<ISession> getLazySession() {
@@ -499,6 +493,10 @@
 
     void setTestHalEnabled(boolean enabled) {
         Slog.w(mTag, "setTestHalEnabled: " + enabled);
+        if (enabled != mTestHalEnabled) {
+            // The framework should retrieve a new session from the HAL.
+            mCurrentSession = null;
+        }
         mTestHalEnabled = enabled;
     }
 
diff --git a/services/core/java/com/android/server/biometrics/sensors/face/aidl/TestHal.java b/services/core/java/com/android/server/biometrics/sensors/face/aidl/TestHal.java
index a38da3a..ff65c93 100644
--- a/services/core/java/com/android/server/biometrics/sensors/face/aidl/TestHal.java
+++ b/services/core/java/com/android/server/biometrics/sensors/face/aidl/TestHal.java
@@ -17,12 +17,14 @@
 package com.android.server.biometrics.sensors.face.aidl;
 
 import android.hardware.biometrics.common.ICancellationSignal;
+import android.hardware.biometrics.face.Error;
 import android.hardware.biometrics.face.IFace;
 import android.hardware.biometrics.face.ISession;
 import android.hardware.biometrics.face.ISessionCallback;
 import android.hardware.biometrics.face.SensorProps;
 import android.hardware.common.NativeHandle;
 import android.hardware.keymaster.HardwareAuthToken;
+import android.os.RemoteException;
 import android.util.Slog;
 
 /**
@@ -38,70 +40,96 @@
 
     @Override
     public ISession createSession(int sensorId, int userId, ISessionCallback cb) {
+        Slog.w(TAG, "createSession, sensorId: " + sensorId + " userId: " + userId);
+
         return new ISession.Stub() {
             @Override
-            public void generateChallenge(int cookie, int timeoutSec) {
+            public void generateChallenge(int cookie, int timeoutSec) throws RemoteException {
                 Slog.w(TAG, "generateChallenge, cookie: " + cookie);
+                cb.onChallengeGenerated(0L);
             }
 
             @Override
-            public void revokeChallenge(int cookie, long challenge) {
+            public void revokeChallenge(int cookie, long challenge) throws RemoteException {
                 Slog.w(TAG, "revokeChallenge: " + challenge + ", cookie: " + cookie);
+                cb.onChallengeRevoked(challenge);
             }
 
             @Override
             public ICancellationSignal enroll(int cookie, HardwareAuthToken hat,
                     byte enrollmentType, byte[] features, NativeHandle previewSurface) {
                 Slog.w(TAG, "enroll, cookie: " + cookie);
-                return null;
+                return new ICancellationSignal.Stub() {
+                    @Override
+                    public void cancel() throws RemoteException {
+                        cb.onError(Error.CANCELED, 0 /* vendorCode */);
+                    }
+                };
             }
 
             @Override
             public ICancellationSignal authenticate(int cookie, long operationId) {
                 Slog.w(TAG, "authenticate, cookie: " + cookie);
-                return null;
+                return new ICancellationSignal.Stub() {
+                    @Override
+                    public void cancel() throws RemoteException {
+                        cb.onError(Error.CANCELED, 0 /* vendorCode */);
+                    }
+                };
             }
 
             @Override
             public ICancellationSignal detectInteraction(int cookie) {
                 Slog.w(TAG, "detectInteraction, cookie: " + cookie);
-                return null;
+                return new ICancellationSignal.Stub() {
+                    @Override
+                    public void cancel() throws RemoteException {
+                        cb.onError(Error.CANCELED, 0 /* vendorCode */);
+                    }
+                };
             }
 
             @Override
-            public void enumerateEnrollments(int cookie) {
+            public void enumerateEnrollments(int cookie) throws RemoteException {
                 Slog.w(TAG, "enumerateEnrollments, cookie: " + cookie);
+                cb.onEnrollmentsEnumerated(new int[0]);
             }
 
             @Override
-            public void removeEnrollments(int cookie, int[] enrollmentIds) {
+            public void removeEnrollments(int cookie, int[] enrollmentIds) throws RemoteException {
                 Slog.w(TAG, "removeEnrollments, cookie: " + cookie);
+                cb.onEnrollmentsRemoved(enrollmentIds);
             }
 
             @Override
-            public void getFeatures(int cookie, int enrollmentId) {
+            public void getFeatures(int cookie, int enrollmentId) throws RemoteException {
                 Slog.w(TAG, "getFeatures, cookie: " + cookie);
+                cb.onFeaturesRetrieved(new byte[0], enrollmentId);
             }
 
             @Override
             public void setFeature(int cookie, HardwareAuthToken hat, int enrollmentId,
-                    byte feature, boolean enabled) {
+                    byte feature, boolean enabled) throws RemoteException {
                 Slog.w(TAG, "setFeature, cookie: " + cookie);
+                cb.onFeatureSet(enrollmentId, feature);
             }
 
             @Override
-            public void getAuthenticatorId(int cookie) {
+            public void getAuthenticatorId(int cookie) throws RemoteException {
                 Slog.w(TAG, "getAuthenticatorId, cookie: " + cookie);
+                cb.onAuthenticatorIdRetrieved(0L);
             }
 
             @Override
-            public void invalidateAuthenticatorId(int cookie) {
+            public void invalidateAuthenticatorId(int cookie) throws RemoteException {
                 Slog.w(TAG, "invalidateAuthenticatorId, cookie: " + cookie);
+                cb.onAuthenticatorIdInvalidated(0L);
             }
 
             @Override
-            public void resetLockout(int cookie, HardwareAuthToken hat) {
+            public void resetLockout(int cookie, HardwareAuthToken hat) throws RemoteException {
                 Slog.w(TAG, "resetLockout, cookie: " + cookie);
+                cb.onLockoutCleared();
             }
         };
     }
diff --git a/services/core/java/com/android/server/biometrics/sensors/face/aidl/TestSession.java b/services/core/java/com/android/server/biometrics/sensors/face/aidl/TestSession.java
deleted file mode 100644
index 23e6988..0000000
--- a/services/core/java/com/android/server/biometrics/sensors/face/aidl/TestSession.java
+++ /dev/null
@@ -1,117 +0,0 @@
-/*
- * 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.server.biometrics.sensors.face.aidl;
-
-import android.annotation.NonNull;
-import android.hardware.biometrics.common.ICancellationSignal;
-import android.hardware.biometrics.face.Error;
-import android.hardware.biometrics.face.ISession;
-import android.hardware.common.NativeHandle;
-import android.hardware.keymaster.HardwareAuthToken;
-import android.os.Binder;
-import android.os.IBinder;
-import android.util.Slog;
-
-/**
- * Test session that provides mostly no-ops.
- */
-public class TestSession extends ISession.Stub {
-    private static final String TAG = "FaceTestSession";
-
-    @NonNull
-    private final Sensor.HalSessionCallback mHalSessionCallback;
-
-    TestSession(@NonNull Sensor.HalSessionCallback halSessionCallback) {
-        mHalSessionCallback = halSessionCallback;
-    }
-
-    @Override
-    public void generateChallenge(int cookie, int timeoutSec) {
-        mHalSessionCallback.onChallengeGenerated(0 /* challenge */);
-    }
-
-    @Override
-    public void revokeChallenge(int cookie, long challenge) {
-        mHalSessionCallback.onChallengeRevoked(challenge);
-    }
-
-    @Override
-    public ICancellationSignal enroll(int cookie, HardwareAuthToken hat, byte enrollmentType,
-            byte[] features, NativeHandle previewSurface) {
-        return null;
-    }
-
-    @Override
-    public ICancellationSignal authenticate(int cookie, long operationId) {
-        return new ICancellationSignal() {
-            @Override
-            public void cancel() {
-                mHalSessionCallback.onError(Error.CANCELED, 0 /* vendorCode */);
-            }
-
-            @Override
-            public IBinder asBinder() {
-                return new Binder();
-            }
-        };
-    }
-
-    @Override
-    public ICancellationSignal detectInteraction(int cookie) {
-        return null;
-    }
-
-    @Override
-    public void enumerateEnrollments(int cookie) {
-
-    }
-
-    @Override
-    public void removeEnrollments(int cookie, int[] enrollmentIds) {
-
-    }
-
-    @Override
-    public void getFeatures(int cookie, int enrollmentId) {
-
-    }
-
-    @Override
-    public void setFeature(int cookie, HardwareAuthToken hat, int enrollmentId, byte feature,
-            boolean enabled) {
-
-    }
-
-    @Override
-    public void getAuthenticatorId(int cookie) {
-        Slog.d(TAG, "getAuthenticatorId");
-        // Immediately return a value so the framework can continue with subsequent requests.
-        mHalSessionCallback.onAuthenticatorIdRetrieved(0);
-    }
-
-    @Override
-    public void invalidateAuthenticatorId(int cookie) {
-        Slog.d(TAG, "invalidateAuthenticatorId");
-        // Immediately return a value so the framework can continue with subsequent requests.
-        mHalSessionCallback.onAuthenticatorIdInvalidated(0);
-    }
-
-    @Override
-    public void resetLockout(int cookie, HardwareAuthToken hat) {
-        mHalSessionCallback.onLockoutCleared();
-    }
-}
diff --git a/services/core/java/com/android/server/biometrics/sensors/face/hidl/TestHal.java b/services/core/java/com/android/server/biometrics/sensors/face/hidl/TestHal.java
index 00ca802..13bd1c2 100644
--- a/services/core/java/com/android/server/biometrics/sensors/face/hidl/TestHal.java
+++ b/services/core/java/com/android/server/biometrics/sensors/face/hidl/TestHal.java
@@ -98,8 +98,11 @@
     }
 
     @Override
-    public int enumerate() {
+    public int enumerate() throws RemoteException {
         Slog.w(TAG, "enumerate");
+        if (mCallback != null) {
+            mCallback.onEnumerate(0 /* deviceId */, new ArrayList<>(), 0 /* userId */);
+        }
         return 0;
     }
 
diff --git a/services/core/java/com/android/server/biometrics/sensors/fingerprint/aidl/Sensor.java b/services/core/java/com/android/server/biometrics/sensors/fingerprint/aidl/Sensor.java
index 6e1d7d6..a4dcac7 100644
--- a/services/core/java/com/android/server/biometrics/sensors/fingerprint/aidl/Sensor.java
+++ b/services/core/java/com/android/server/biometrics/sensors/fingerprint/aidl/Sensor.java
@@ -416,13 +416,7 @@
         mScheduler = new BiometricScheduler(tag, gestureAvailabilityDispatcher);
         mLockoutCache = new LockoutCache();
         mAuthenticatorIds = new HashMap<>();
-        mLazySession = () -> {
-            if (mTestHalEnabled) {
-                return new TestSession(mCurrentSession.mHalSessionCallback);
-            } else {
-                return mCurrentSession != null ? mCurrentSession.mSession : null;
-            }
-        };
+        mLazySession = () -> mCurrentSession != null ? mCurrentSession.mSession : null;
     }
 
     @NonNull HalClientMonitor.LazyDaemon<ISession> getLazySession() {
@@ -478,7 +472,11 @@
     }
 
     void setTestHalEnabled(boolean enabled) {
-        Slog.w(mTag, "setTestHalEnabled, enabled");
+        Slog.w(mTag, "setTestHalEnabled: " + enabled);
+        if (enabled != mTestHalEnabled) {
+            // The framework should retrieve a new session from the HAL.
+            mCurrentSession = null;
+        }
         mTestHalEnabled = enabled;
     }
 
diff --git a/services/core/java/com/android/server/biometrics/sensors/fingerprint/aidl/TestHal.java b/services/core/java/com/android/server/biometrics/sensors/fingerprint/aidl/TestHal.java
index 66b68ee..8ed24b6 100644
--- a/services/core/java/com/android/server/biometrics/sensors/fingerprint/aidl/TestHal.java
+++ b/services/core/java/com/android/server/biometrics/sensors/fingerprint/aidl/TestHal.java
@@ -17,11 +17,13 @@
 package com.android.server.biometrics.sensors.fingerprint.aidl;
 
 import android.hardware.biometrics.common.ICancellationSignal;
+import android.hardware.biometrics.fingerprint.Error;
 import android.hardware.biometrics.fingerprint.IFingerprint;
 import android.hardware.biometrics.fingerprint.ISession;
 import android.hardware.biometrics.fingerprint.ISessionCallback;
 import android.hardware.biometrics.fingerprint.SensorProps;
 import android.hardware.keymaster.HardwareAuthToken;
+import android.os.RemoteException;
 import android.util.Slog;
 
 /**
@@ -38,58 +40,82 @@
 
     @Override
     public ISession createSession(int sensorId, int userId, ISessionCallback cb) {
+        Slog.w(TAG, "createSession, sensorId: " + sensorId + " userId: " + userId);
+
         return new ISession.Stub() {
             @Override
-            public void generateChallenge(int cookie, int timeoutSec) {
+            public void generateChallenge(int cookie, int timeoutSec) throws RemoteException {
                 Slog.w(TAG, "generateChallenge, cookie: " + cookie);
+                cb.onChallengeGenerated(0L);
             }
 
             @Override
-            public void revokeChallenge(int cookie, long challenge) {
+            public void revokeChallenge(int cookie, long challenge) throws RemoteException {
                 Slog.w(TAG, "revokeChallenge: " + challenge + ", cookie: " + cookie);
+                cb.onChallengeRevoked(challenge);
             }
 
             @Override
             public ICancellationSignal enroll(int cookie, HardwareAuthToken hat) {
                 Slog.w(TAG, "enroll, cookie: " + cookie);
-                return null;
+                return new ICancellationSignal.Stub() {
+                    @Override
+                    public void cancel() throws RemoteException {
+                        cb.onError(Error.CANCELED, 0 /* vendorCode */);
+                    }
+                };
             }
 
             @Override
             public ICancellationSignal authenticate(int cookie, long operationId) {
                 Slog.w(TAG, "authenticate, cookie: " + cookie);
-                return null;
+                return new ICancellationSignal.Stub() {
+                    @Override
+                    public void cancel() throws RemoteException {
+                        cb.onError(Error.CANCELED, 0 /* vendorCode */);
+                    }
+                };
             }
 
             @Override
             public ICancellationSignal detectInteraction(int cookie) {
                 Slog.w(TAG, "detectInteraction, cookie: " + cookie);
-                return null;
+                return new ICancellationSignal.Stub() {
+                    @Override
+                    public void cancel() throws RemoteException {
+                        cb.onError(Error.CANCELED, 0 /* vendorCode */);
+                    }
+                };
             }
 
             @Override
-            public void enumerateEnrollments(int cookie) {
+            public void enumerateEnrollments(int cookie) throws RemoteException {
                 Slog.w(TAG, "enumerateEnrollments, cookie: " + cookie);
+                cb.onEnrollmentsEnumerated(new int[0]);
             }
 
             @Override
-            public void removeEnrollments(int cookie, int[] enrollmentIds) {
+            public void removeEnrollments(int cookie, int[] enrollmentIds) throws RemoteException {
                 Slog.w(TAG, "removeEnrollments, cookie: " + cookie);
+                cb.onEnrollmentsRemoved(enrollmentIds);
             }
 
             @Override
-            public void getAuthenticatorId(int cookie) {
+            public void getAuthenticatorId(int cookie) throws RemoteException {
                 Slog.w(TAG, "getAuthenticatorId, cookie: " + cookie);
+                cb.onAuthenticatorIdRetrieved(0L);
             }
 
             @Override
-            public void invalidateAuthenticatorId(int cookie) {
+            public void invalidateAuthenticatorId(int cookie) throws RemoteException {
                 Slog.w(TAG, "invalidateAuthenticatorId, cookie: " + cookie);
+                cb.onAuthenticatorIdInvalidated(0L);
             }
 
             @Override
-            public void resetLockout(int cookie, HardwareAuthToken hat) {
+            public void resetLockout(int cookie, HardwareAuthToken hat) throws RemoteException {
                 Slog.w(TAG, "resetLockout, cookie: " + cookie);
+                cb.onLockoutCleared();
             }
 
             @Override
diff --git a/services/core/java/com/android/server/biometrics/sensors/fingerprint/aidl/TestSession.java b/services/core/java/com/android/server/biometrics/sensors/fingerprint/aidl/TestSession.java
deleted file mode 100644
index ac4f665..0000000
--- a/services/core/java/com/android/server/biometrics/sensors/fingerprint/aidl/TestSession.java
+++ /dev/null
@@ -1,119 +0,0 @@
-/*
- * 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.server.biometrics.sensors.fingerprint.aidl;
-
-import android.annotation.NonNull;
-import android.hardware.biometrics.common.ICancellationSignal;
-import android.hardware.biometrics.face.Error;
-import android.hardware.biometrics.fingerprint.ISession;
-import android.hardware.keymaster.HardwareAuthToken;
-import android.os.Binder;
-import android.os.IBinder;
-import android.util.Slog;
-
-/**
- * Test session that provides mostly no-ops.
- */
-class TestSession extends ISession.Stub {
-
-    private static final String TAG = "FingerprintTestSession";
-
-    @NonNull private final Sensor.HalSessionCallback mHalSessionCallback;
-
-    TestSession(@NonNull Sensor.HalSessionCallback halSessionCallback) {
-        mHalSessionCallback = halSessionCallback;
-    }
-
-    @Override
-    public void generateChallenge(int cookie, int timeoutSec) {
-        mHalSessionCallback.onChallengeGenerated(0 /* challenge */);
-    }
-
-    @Override
-    public void revokeChallenge(int cookie, long challenge) {
-        mHalSessionCallback.onChallengeRevoked(challenge);
-    }
-
-    @Override
-    public ICancellationSignal enroll(int cookie, HardwareAuthToken hat) {
-        return null;
-    }
-
-    @Override
-    public ICancellationSignal authenticate(int cookie, long operationId) {
-        return new ICancellationSignal() {
-            @Override
-            public void cancel() {
-                mHalSessionCallback.onError(Error.CANCELED, 0 /* vendorCode */);
-            }
-
-            @Override
-            public IBinder asBinder() {
-                return new Binder();
-            }
-        };
-    }
-
-    @Override
-    public ICancellationSignal detectInteraction(int cookie) {
-        return null;
-    }
-
-    @Override
-    public void enumerateEnrollments(int cookie) {
-        Slog.d(TAG, "enumerate");
-    }
-
-    @Override
-    public void removeEnrollments(int cookie, int[] enrollmentIds) {
-        Slog.d(TAG, "remove");
-    }
-
-    @Override
-    public void getAuthenticatorId(int cookie) {
-        Slog.d(TAG, "getAuthenticatorId");
-        // Immediately return a value so the framework can continue with subsequent requests.
-        mHalSessionCallback.onAuthenticatorIdRetrieved(0);
-    }
-
-    @Override
-    public void invalidateAuthenticatorId(int cookie) {
-        Slog.d(TAG, "invalidateAuthenticatorId");
-        // Immediately return a value so the framework can continue with subsequent requests.
-        mHalSessionCallback.onAuthenticatorIdInvalidated(0);
-    }
-
-    @Override
-    public void resetLockout(int cookie, HardwareAuthToken hat) {
-        mHalSessionCallback.onLockoutCleared();
-    }
-
-    @Override
-    public void onPointerDown(int pointerId, int x, int y, float minor, float major) {
-
-    }
-
-    @Override
-    public void onPointerUp(int pointerId) {
-
-    }
-
-    @Override
-    public void onUiReady() {
-
-    }
-}
diff --git a/services/core/java/com/android/server/biometrics/sensors/fingerprint/hidl/TestHal.java b/services/core/java/com/android/server/biometrics/sensors/fingerprint/hidl/TestHal.java
index 57447f3..14fdb50 100644
--- a/services/core/java/com/android/server/biometrics/sensors/fingerprint/hidl/TestHal.java
+++ b/services/core/java/com/android/server/biometrics/sensors/fingerprint/hidl/TestHal.java
@@ -83,8 +83,12 @@
     }
 
     @Override
-    public int enumerate() {
+    public int enumerate() throws RemoteException {
         Slog.w(TAG, "Enumerate");
+        if (mCallback != null) {
+            mCallback.onEnumerate(0 /* deviceId */, 0 /* fingerId */, 0 /* groupId */,
+                    0 /* remaining */);
+        }
         return 0;
     }