将 JUnit 与 App Engine 和 Eclipse 结合使用

Question

我在 Eclipse 中使用 App Engine 设置 JUnit 时遇到问题。我已经正确设置了 JUnit，也就是说，我可以运行不涉及数据存储或其他服务的测试。但是，当我尝试在测试中使用数据存储时，它们会失败。我现在正在尝试的代码来自 App Engine 网站（见下文）：

http://code.google.com/appengine/docs/java/tools/localunittesting.html#Running_Tests

到目前为止，我已经添加了外部 JAR（使用 Eclipse）appengine-testing.jar。但是当我运行测试时，我得到了下面的异常。因此，我显然不理解从上述网页启用服务的说明。有人可以弄清楚在 Eclipse 中提供 App Engine 服务所需的步骤吗？

java.lang.NoClassDefFoundError: com/google/appengine/api/datastore/dev/LocalDatastoreService
at com.google.appengine.tools.development.testing.LocalDatastoreServiceTestConfig.tearDown(LocalDatastoreServiceTestConfig.java:138)
at com.google.appengine.tools.development.testing.LocalServiceTestHelper.tearDown(LocalServiceTestHelper.java:254)
at com.cooperconrad.server.MemberTest.tearDown(MemberTest.java:28)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:37)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:73)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:46)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:180)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:41)
at org.junit.runners.ParentRunner$1.evaluate(ParentRunner.java:173)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
at org.junit.runners.ParentRunner.run(ParentRunner.java:220)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:46)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.lang.ClassNotFoundException: com.google.appengine.api.datastore.dev.LocalDatastoreService
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
... 25 more

这是实际代码（几乎从网站复制）：

package com.example;

import static org.junit.Assert.*;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import com.google.appengine.api.datastore.DatastoreService;
import com.google.appengine.api.datastore.DatastoreServiceFactory;
import com.google.appengine.api.datastore.Entity;
import com.google.appengine.api.datastore.Query;
import com.google.appengine.tools.development.testing.LocalDatastoreServiceTestConfig;
import com.google.appengine.tools.development.testing.LocalServiceTestHelper;

public class MemberTest
{
    private final LocalServiceTestHelper helper = new LocalServiceTestHelper(new LocalDatastoreServiceTestConfig());

    @Before
    public void setUp() {
        helper.setUp();
    }

    @After
    public void tearDown() {
        helper.tearDown();
    }

    // run this test twice to prove we're not leaking any state across tests
    private void doTest() {
        DatastoreService ds = DatastoreServiceFactory.getDatastoreService();
        assertEquals(0, ds.prepare(new Query("yam")).countEntities());
        ds.put(new Entity("yam"));
        ds.put(new Entity("yam"));
        assertEquals(2, ds.prepare(new Query("yam")).countEntities());
    }

    @Test
    public void testInsert1() {
        doTest();
    }

    @Test
    public void testInsert2() {
        doTest();
    }

    @Test
    public void foo()
    {
        assertEquals(4, 2 + 2);
    }
}

Answer 1

在 Eclipse 中，您是否添加了所有提到的 here 的 jar？除了 appengine-testing.jar，您还需要几个 jar。

但是，如果您的测试或被测代码具有这些依赖项，您将需要在测试类路径中添加更多 JAR：${SDK_ROOT}/lib/impl/appengine-api.jar、${SDK_ROOT}/lib/ impl/appengine-api-labs.jar 和 ${SDK_ROOT}/lib/impl/appengine-api-stubs.jar。这些 JAR 使运行时 API 和这些 API 的本地实现可用于您的测试。

Answer 2

Peter's answer 是正确的：你需要这些库：

appengine-api.jar
appengine-api-labs.jar
appengine-api-stubs.jar
appengine-tools-api.jar

您可能已经拥有第一个，而只需要最后三个。

如果您使用的是 Maven，可以将这些依赖项添加到 pom.xml：

<dependency>
  <groupId>com.google.appengine</groupId>
  <artifactId>appengine-api-labs</artifactId>
  <version>1.9.60</version>
  <scope>test</scope>
</dependency>

<dependency>
  <groupId>com.google.appengine</groupId>
  <artifactId>appengine-api-stubs</artifactId>
  <version>1.9.60</version>
  <scope>test</scope>
</dependency>

<dependency>
  <groupId>com.google.appengine</groupId>
  <artifactId>appengine-tools-sdk</artifactId>
  <version>1.9.60</version>
  <scope>test</scope>
</dependency>