如何使用 JUnit4 测试 maven 插件

Question

我正在编写一个 maven 插件并想编写一些 JUnit 测试。我按照Maven Plugin Testing 中的描述进行操作。不幸的是，在我可以配置或调用任何东西之前，我在测试设置期间不断收到异常。

这是我的 JUnit 测试代码：

public class ResetMojoTest {

    private static final String POM_FILE_NAME = "/path/to/pom.xml"; 

    @Rule
    public MojoRule rule = new MojoRule();

    @Test
    public void testSomething()
        throws Exception
    {
        File pom = new File(POM_FILE_NAME);
        Assert.assertNotNull( pom );
        Assert.assertTrue( pom.exists() );

        ResetMojo resetMojo = (ResetMojo) rule.lookupMojo( "touch", pom );
        Assert.assertNotNull( resetMojo );
        resetMojo.execute();
    }

}

这是异常的堆栈跟踪：

java.io.IOException: Stream closed
    at java.io.BufferedInputStream.getInIfOpen(BufferedInputStream.java:134)
    at java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
    at java.io.BufferedInputStream.read(BufferedInputStream.java:237)
    at org.apache.commons.io.input.BOMInputStream.getBOM(BOMInputStream.java:175)
    at org.apache.commons.io.input.BOMInputStream.getBOMCharsetName(BOMInputStream.java:201)
    at org.apache.commons.io.input.XmlStreamReader.doRawStream(XmlStreamReader.java:412)
    at org.apache.commons.io.input.XmlStreamReader.<init>(XmlStreamReader.java:206)
    at org.apache.commons.io.input.XmlStreamReader.<init>(XmlStreamReader.java:171)
    at org.apache.commons.io.input.XmlStreamReader.<init>(XmlStreamReader.java:140)
    at org.apache.maven.plugin.testing.AbstractMojoTestCase.setUp(AbstractMojoTestCase.java:119)
    at org.apache.maven.plugin.testing.MojoRule$2.evaluate(MojoRule.java:299)
    at org.junit.rules.RunRules.evaluate(RunRules.java:20)

关于如何使它工作的任何想法？

Answer 1

也遇到了这个问题。 mojo 规则失败，因为它实例化了AbstractMojoTestCase 的匿名实现，然后它会查找它，然后尝试在此处创建一个加载数据的输入流：InputStream is = getClass().getResourceAsStream( "/" + getPluginDescriptorLocation() );。这（getPluginDescriptorLocation()）只是一个硬编码的文件字符串"META-INF/maven/plugin.xml"。

我通过添加以下依赖项解决了这个问题：

<dependency>
  <groupId>org.apache.maven</groupId>
  <artifactId>maven-compat</artifactId>
  <version>3.5.0</version>
</dependency>

我不确定为什么这可以解决问题。该文件仍然不存在（我已经检查了原始来源和target 目录，但两者都不存在）。因此，需要进行额外的搜索才能弄清楚为什么会这样。

这是我的依赖项供参考。

<dependency>
  <groupId>org.apache.maven</groupId>
  <artifactId>maven-plugin-api</artifactId>
  <version>3.5.0</version>
</dependency>
<dependency>
  <groupId>org.twdata.maven</groupId>
  <artifactId>mojo-executor</artifactId>
  <version>2.3.0</version>
</dependency>
<dependency>
  <groupId>org.apache.maven.plugin-tools</groupId>
  <artifactId>maven-plugin-annotations</artifactId>
  <version>3.5</version>
  <scope>provided</scope>
</dependency>
<dependency>
  <groupId>org.eclipse.aether</groupId>
  <artifactId>aether-api</artifactId>
  <version>1.1.0</version>
</dependency>
<dependency>
  <groupId>org.apache.maven</groupId>
  <artifactId>maven-core</artifactId>
  <version>3.5.0</version>
</dependency>
<dependency>
  <groupId>org.apache.maven</groupId>
  <artifactId>maven-compat</artifactId>
  <version>3.5.0</version>
</dependency>
<!--Test Dependencies-->
<dependency>
  <groupId>junit</groupId>
  <artifactId>junit</artifactId>
  <version>4.12</version>
  <scope>test</scope>
</dependency>
<dependency>
  <groupId>org.apache.maven.plugin-testing</groupId>
  <artifactId>maven-plugin-testing-harness</artifactId>
  <version>3.3.0</version>
  <scope>test</scope>
</dependency>

Answer 2

遇到同样的问题。通过添加正确的依赖项来解决它。重要的是标记为由harness maven插件提供的依赖项被添加到测试范围：

<properties>
  <dependency.maven.version>3.3.9</dependency.maven.version>
  <!-- and others -->
</properties>

<dependencies>
  <!-- your dependencies -->

  <!-- maven plugin dependencies -->
  <dependency>
    <groupId>org.apache.maven</groupId>
    <artifactId>maven-plugin-api</artifactId>
    <version>${dependency.maven.version}</version>
  </dependency>
  <dependency>
    <groupId>org.apache.maven</groupId>
    <artifactId>maven-core</artifactId>
    <version>${dependency.maven.version}</version>
  </dependency>
  <dependency>
    <groupId>org.apache.maven</groupId>
    <artifactId>maven-model</artifactId>
    <version>${dependency.maven.version}</version>
  </dependency>
  <dependency>
    <groupId>org.apache.maven</groupId>
    <artifactId>maven-artifact</artifactId>
    <version>${dependency.maven.version}</version>
  </dependency>

  <!-- test dependencies -->
  <dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>${dependency.junit.version}</version>
    <scope>test</scope>
  </dependency>
  <dependency>
    <groupId>org.apache.maven.plugin-testing</groupId>
    <artifactId>maven-plugin-testing-harness</artifactId>
    <version>3.3.0</version>
    <scope>test</scope>
  </dependency>
  <dependency>
    <groupId>org.apache.maven</groupId>
    <artifactId>maven-aether-provider</artifactId>
    <version>${dependency.maven.version}</version>
    <scope>test</scope>
  </dependency>
  <dependency>
    <groupId>org.apache.maven</groupId>
    <artifactId>maven-compat</artifactId>
    <version>${dependency.maven.version}</version>
    <scope>test</scope>
  </dependency>

  <!-- provided maven dependencies -->
  <dependency>
    <groupId>org.apache.maven.plugin-tools</groupId>
    <artifactId>maven-plugin-annotations</artifactId>
    <version>3.3</version>
    <scope>provided</scope>
  </dependency>

</dependencies>

你的测试类应该是这样的

public class YourMojoTest {

  @Rule
  public MojoRule rule = new MojoRule();

  @Test
  public void shouldExecuteMojo() throws Exception {
    // given
    File testPom = new File(PlexusTestCase.getBasedir(), "src/test/resources/pom.xml");

    final Properties properties = new Properties();
    final MavenProject mavenProject = Mockito.mock(MavenProject.class);
    Mockito.when(mavenProject.getProperties()).thenReturn(properties);

    // when
    YourMojo mojo = (YourMojo) rule.lookupMojo("fetch", testPom);
    assertNotNull(mojo);
    mojo.setProject(mavenProject);
    mojo.execute();

    // then
    // do your tests ...
  }
}

希望这对其他在同一问题上苦苦挣扎的人有所帮助

Answer 3

POM文件的加载不好看：

以下代码来自示例：

File pom = rule.getTestFile( "src/test/resources/unit/project-to-test/pom.xml" );

这就是你所拥有的：

File pom = new File(POM_FILE_NAME);

除此之外，您还有一个不同的位置，如下所示：

private static final String POM_FILE_NAME = "/path/to/pom.xml"; 

但是pom文件的位置应该是：

private static final String POM_FILE_NAME = "src/test/resources/pom.xml";