diff --git a/core/src/test/java/io/temporal/samples/sleepfordays/SleepForDaysJUnit5Test.java b/core/src/test/java/io/temporal/samples/sleepfordays/SleepForDaysJUnit5Test.java
new file mode 100644
index 000000000..44e1f9e68
--- /dev/null
+++ b/core/src/test/java/io/temporal/samples/sleepfordays/SleepForDaysJUnit5Test.java
@@ -0,0 +1,74 @@
+/*
+ *  Copyright (c) 2020 Temporal Technologies, Inc. All Rights Reserved
+ *
+ *  Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Modifications copyright (C) 2017 Uber Technologies, Inc.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"). You may not
+ *  use this file except in compliance with the License. A copy of the License is
+ *  located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ *  or in the "license" file accompanying this file. This file 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 io.temporal.samples.sleepfordays;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.Mockito.*;
+
+import io.temporal.client.WorkflowClient;
+import io.temporal.testing.TestWorkflowEnvironment;
+import io.temporal.testing.TestWorkflowExtension;
+import io.temporal.worker.Worker;
+import java.time.Duration;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Timeout;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+public class SleepForDaysJUnit5Test {
+
+  @RegisterExtension
+  public TestWorkflowExtension testWorkflowRule =
+      TestWorkflowExtension.newBuilder()
+          .registerWorkflowImplementationTypes(SleepForDaysImpl.class)
+          .setDoNotStart(true)
+          .build();
+
+  @Test
+  @Timeout(8)
+  public void testSleepForDays(
+      TestWorkflowEnvironment testEnv, Worker worker, SleepForDaysWorkflow workflow) {
+    // Mock activity
+    SendEmailActivity activities = mock(SendEmailActivity.class);
+    worker.registerActivitiesImplementations(activities);
+    // Start environment
+    testEnv.start();
+
+    // Start workflow
+    WorkflowClient.start(workflow::sleepForDays);
+
+    long startTime = testEnv.currentTimeMillis();
+    // Time-skip 5 minutes.
+    testEnv.sleep(Duration.ofMinutes(5));
+    // Check that the activity has been called, we're now waiting for the sleep to finish.
+    verify(activities, times(1)).sendEmail(anyString());
+    // Time-skip 3 days.
+    testEnv.sleep(Duration.ofDays(90));
+    // Expect 3 more activity calls.
+    verify(activities, times(4)).sendEmail(anyString());
+    // Send the signal to complete the workflow.
+    workflow.complete();
+    // Expect no more activity calls to have been made - workflow is complete.
+    workflow.sleepForDays();
+    verify(activities, times(4)).sendEmail(anyString());
+    // Expect more than 90 days to have passed.
+    long endTime = testEnv.currentTimeMillis();
+    assertEquals(true, endTime - startTime > Duration.ofDays(90).toMillis());
+  }
+}