code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC licenses this file
  // to you 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 org.openqa.selenium.support;
  
  import static org.assertj.core.api.Assertions.assertThat;
  import static org.mockito.Mockito.mock;
  
  import java.util.concurrent.atomic.AtomicInteger;
  import org.junit.jupiter.api.Tag;
  import org.junit.jupiter.api.Test;
  import org.openqa.selenium.By;
  import org.openqa.selenium.WebDriver;
  
  @Tag("UnitTests")
  class ThreadGuardTest {
  
    @Test
    void testProtect() throws Exception {
      WebDriver actual = mock(WebDriver.class);
      final WebDriver protect = ThreadGuard.protect(actual);
      final AtomicInteger successes = new AtomicInteger();
      Thread foo =
          new Thread(
              () -> {
                protect.findElement(By.id("foo"));
                successes.incrementAndGet();
              });
      foo.start();
      foo.join();
      assertThat(successes.get()).isZero();
    }
  
    @Test
    void testProtectSuccess() {
      WebDriver actual = mock(WebDriver.class);
      final WebDriver protect = ThreadGuard.protect(actual);
      assertThat(protect.findElement(By.id("foo"))).isNull();
    }
  }
  