diff --git a/ravenwood/bulk_enable.py b/ravenwood/bulk_enable.py
index 83fda9e..aafaaff 100644
--- a/ravenwood/bulk_enable.py
+++ b/ravenwood/bulk_enable.py
@@ -21,7 +21,7 @@
 classes that have partial success.
 
 Typical usage:
-$ ENABLE_PROBE_IGNORED=1 atest MyTestsRavenwood
+$ RAVENWOOD_RUN_DISABLED_TESTS=1 atest MyTestsRavenwood
 $ cd /path/to/tests/root
 $ python bulk_enable.py /path/to/atest/output/host_log.txt
 """
diff --git a/ravenwood/coretest/Android.bp b/ravenwood/coretest/Android.bp
new file mode 100644
index 0000000..9b7f8f7
--- /dev/null
+++ b/ravenwood/coretest/Android.bp
@@ -0,0 +1,23 @@
+package {
+    // See: http://go/android-license-faq
+    // A large-scale-change added 'default_applicable_licenses' to import
+    // all of the 'license_kinds' from "frameworks_base_license"
+    // to get the below license kinds:
+    //   SPDX-license-identifier-Apache-2.0
+    default_applicable_licenses: ["frameworks_base_license"],
+}
+
+android_ravenwood_test {
+    name: "RavenwoodCoreTest",
+
+    static_libs: [
+        "androidx.annotation_annotation",
+        "androidx.test.rules",
+    ],
+
+    srcs: [
+        "test/**/*.java",
+    ],
+    sdk_version: "test_current",
+    auto_gen_config: true,
+}
diff --git a/ravenwood/coretest/test/com/android/platform/test/ravenwood/coretest/RavenwoodTestRunnerValidationTest.java b/ravenwood/coretest/test/com/android/platform/test/ravenwood/coretest/RavenwoodTestRunnerValidationTest.java
new file mode 100644
index 0000000..e58c282
--- /dev/null
+++ b/ravenwood/coretest/test/com/android/platform/test/ravenwood/coretest/RavenwoodTestRunnerValidationTest.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2024 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.platform.test.ravenwood.coretest;
+
+import android.platform.test.ravenwood.RavenwoodRule;
+
+import androidx.test.runner.AndroidJUnit4;
+
+import org.junit.Assume;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.junit.rules.RuleChain;
+import org.junit.runner.RunWith;
+
+/**
+ * Test for the test runner validator in RavenwoodRule.
+ */
+@RunWith(AndroidJUnit4.class)
+public class RavenwoodTestRunnerValidationTest {
+    // Note the following rules don't have a @Rule, because they need to be applied in a specific
+    // order. So we use a RuleChain instead.
+    private ExpectedException mThrown = ExpectedException.none();
+    private final RavenwoodRule mRavenwood = new RavenwoodRule();
+
+    @Rule
+    public final RuleChain chain = RuleChain.outerRule(mThrown).around(mRavenwood);
+
+    public RavenwoodTestRunnerValidationTest() {
+        Assume.assumeTrue(mRavenwood._ravenwood_private$isOptionalValidationEnabled());
+        // Because RavenwoodRule will throw this error before executing the test method,
+        // we can't do it in the test method itself.
+        // So instead, we initialize it here.
+        mThrown.expectMessage("Switch to androidx.test.ext.junit.runners.AndroidJUnit4");
+    }
+
+    @Test
+    public void testValidateTestRunner() {
+    }
+}
diff --git a/ravenwood/fix_test_runner.py b/ravenwood/fix_test_runner.py
new file mode 100755
index 0000000..99b7a1f
--- /dev/null
+++ b/ravenwood/fix_test_runner.py
@@ -0,0 +1,68 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2024 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Tool switch the deprecated jetpack test runner to the correct one.
+
+Typical usage:
+$ RAVENWOOD_OPTIONAL_VALIDATION=1 atest MyTestsRavenwood # Prepend RAVENWOOD_RUN_DISABLED_TESTS=1 as needed
+$ cd /path/to/tests/root
+$ python bulk_enable.py /path/to/atest/output/host_log.txt
+"""
+
+import collections
+import os
+import re
+import subprocess
+import sys
+
+re_result = re.compile("I/ModuleListener.+?null-device-0 (.+?)#(.+?) ([A-Z_]+)(.*)$")
+
+OLD_RUNNER = "androidx.test.runner.AndroidJUnit4"
+NEW_RUNNER = "androidx.test.ext.junit.runners.AndroidJUnit4"
+SED_ARG = r"s/%s/%s/g" % (OLD_RUNNER, NEW_RUNNER)
+
+target = collections.defaultdict()
+
+with open(sys.argv[1]) as f:
+    for line in f.readlines():
+        result = re_result.search(line)
+        if result:
+            clazz, method, state, msg = result.groups()
+            if NEW_RUNNER in msg:
+                target[clazz] = 1
+
+if len(target) == 0:
+    print("No tests need updating.")
+    sys.exit(0)
+
+num_fixed = 0
+for clazz in target.keys():
+    print("Fixing test runner", clazz)
+    clazz_match = re.compile("%s\.(kt|java)" % (clazz.split(".")[-1]))
+    found = False
+    for root, dirs, files in os.walk("."):
+        for f in files:
+            if clazz_match.match(f):
+                found = True
+                num_fixed += 1
+                path = os.path.join(root, f)
+                subprocess.run(["sed", "-i", "-E", SED_ARG, path])
+    if not found:
+        print(f"  Warining: tests {clazz} not found")
+
+
+print("Tests fixed", num_fixed)
diff --git a/ravenwood/junit-impl-src/android/platform/test/ravenwood/RavenwoodRuleImpl.java b/ravenwood/junit-impl-src/android/platform/test/ravenwood/RavenwoodRuleImpl.java
index 8af561f..85fa65a 100644
--- a/ravenwood/junit-impl-src/android/platform/test/ravenwood/RavenwoodRuleImpl.java
+++ b/ravenwood/junit-impl-src/android/platform/test/ravenwood/RavenwoodRuleImpl.java
@@ -28,7 +28,10 @@
 
 import com.android.internal.os.RuntimeInit;
 
+import org.junit.Assert;
 import org.junit.runner.Description;
+import org.junit.runner.RunWith;
+import org.junit.runners.model.Statement;
 
 import java.io.PrintStream;
 import java.util.Map;
@@ -167,4 +170,31 @@
             }
         }
     }
+
+    public static void validate(Statement base, Description description,
+            boolean enableOptionalValidation) {
+        validateTestRunner(base, description, enableOptionalValidation);
+    }
+
+    private static void validateTestRunner(Statement base, Description description,
+            boolean shouldFail) {
+        final var testClass = description.getTestClass();
+        final var runWith = testClass.getAnnotation(RunWith.class);
+        if (runWith == null) {
+            return;
+        }
+
+        // Due to build dependencies, we can't directly refer to androidx classes here,
+        // so just check the class name instead.
+        if (runWith.value().getCanonicalName().equals("androidx.test.runner.AndroidJUnit4")) {
+            var message = "Test " + testClass.getCanonicalName() + " uses deprecated"
+                    + " test runner androidx.test.runner.AndroidJUnit4."
+                    + " Switch to androidx.test.ext.junit.runners.AndroidJUnit4.";
+            if (shouldFail) {
+                Assert.fail(message);
+            } else {
+                System.err.println("Warning: " + message);
+            }
+        }
+    }
 }
diff --git a/ravenwood/junit-src/android/platform/test/ravenwood/RavenwoodRule.java b/ravenwood/junit-src/android/platform/test/ravenwood/RavenwoodRule.java
index daed457..764573d 100644
--- a/ravenwood/junit-src/android/platform/test/ravenwood/RavenwoodRule.java
+++ b/ravenwood/junit-src/android/platform/test/ravenwood/RavenwoodRule.java
@@ -89,6 +89,12 @@
     private static final boolean ENABLE_REALLY_DISABLE_PATTERN =
             !REALLY_DISABLE_PATTERN.pattern().isEmpty();
 
+    /**
+     * If true, enable optional validation on running tests.
+     */
+    private static final boolean ENABLE_OPTIONAL_VALIDATION = "1".equals(
+            System.getenv("RAVENWOOD_OPTIONAL_VALIDATION"));
+
     static {
         if (ENABLE_PROBE_IGNORED) {
             System.out.println("$RAVENWOOD_RUN_DISABLED_TESTS enabled: force running all tests");
@@ -275,6 +281,12 @@
         }
     }
 
+    private void commonPrologue(Statement base, Description description) {
+        RavenwoodRuleImpl.logTestRunner("started", description);
+        RavenwoodRuleImpl.validate(base, description, ENABLE_OPTIONAL_VALIDATION);
+        RavenwoodRuleImpl.init(RavenwoodRule.this);
+    }
+
     /**
      * Run the given {@link Statement} with no special treatment.
      */
@@ -284,8 +296,7 @@
             public void evaluate() throws Throwable {
                 Assume.assumeTrue(shouldEnableOnRavenwood(description));
 
-                RavenwoodRuleImpl.logTestRunner("started", description);
-                RavenwoodRuleImpl.init(RavenwoodRule.this);
+                commonPrologue(base, description);
                 try {
                     base.evaluate();
                     RavenwoodRuleImpl.logTestRunner("finished", description);
@@ -310,8 +321,7 @@
             public void evaluate() throws Throwable {
                 Assume.assumeFalse(shouldStillIgnoreInProbeIgnoreMode(description));
 
-                RavenwoodRuleImpl.logTestRunner("started", description);
-                RavenwoodRuleImpl.init(RavenwoodRule.this);
+                commonPrologue(base, description);
                 try {
                     base.evaluate();
                 } catch (Throwable t) {
@@ -331,4 +341,11 @@
             }
         };
     }
+
+    /**
+     * Do not use it outside ravenwood core classes.
+     */
+    public boolean _ravenwood_private$isOptionalValidationEnabled() {
+        return ENABLE_OPTIONAL_VALIDATION;
+    }
 }
diff --git a/ravenwood/junit-stub-src/android/platform/test/ravenwood/RavenwoodRuleImpl.java b/ravenwood/junit-stub-src/android/platform/test/ravenwood/RavenwoodRuleImpl.java
index 7d172f2..e951351b 100644
--- a/ravenwood/junit-stub-src/android/platform/test/ravenwood/RavenwoodRuleImpl.java
+++ b/ravenwood/junit-stub-src/android/platform/test/ravenwood/RavenwoodRuleImpl.java
@@ -17,6 +17,7 @@
 package android.platform.test.ravenwood;
 
 import org.junit.runner.Description;
+import org.junit.runners.model.Statement;
 
 public class RavenwoodRuleImpl {
     public static boolean isOnRavenwood() {
@@ -34,4 +35,8 @@
     public static void logTestRunner(String label, Description description) {
         // No-op when running on a real device
     }
+
+    public static void validate(Statement base, Description description,
+            boolean enableOptionalValidation) {
+    }
 }
diff --git a/ravenwood/minimum-test/Android.bp b/ravenwood/minimum-test/Android.bp
index bf3583c..e4ed3d5 100644
--- a/ravenwood/minimum-test/Android.bp
+++ b/ravenwood/minimum-test/Android.bp
@@ -13,6 +13,7 @@
 
     static_libs: [
         "androidx.annotation_annotation",
+        "androidx.test.ext.junit",
         "androidx.test.rules",
     ],
 
diff --git a/ravenwood/minimum-test/test/com/android/ravenwood/RavenwoodMinimumTest.java b/ravenwood/minimum-test/test/com/android/ravenwood/RavenwoodMinimumTest.java
index 7abfecf..03cfad5 100644
--- a/ravenwood/minimum-test/test/com/android/ravenwood/RavenwoodMinimumTest.java
+++ b/ravenwood/minimum-test/test/com/android/ravenwood/RavenwoodMinimumTest.java
@@ -18,7 +18,7 @@
 import android.platform.test.annotations.IgnoreUnderRavenwood;
 import android.platform.test.ravenwood.RavenwoodRule;
 
-import androidx.test.runner.AndroidJUnit4;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
 
 import org.junit.Assert;
 import org.junit.Rule;