使用 JaCoCo 和 spring-boot-maven-plugin 生成代码覆盖率

Question

在集成测试期间，我使用 spring-boot-maven-plugin 来启动我的 spring 应用程序：

<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
    <executions>
         <execution>
             <id>start-spring-boot</id>
             <phase>pre-integration-test</phase>
             <goals>
                 <goal>start</goal>
             </goals>
         </execution>
         <execution>
             <id>stop-spring-boot</id>
             <phase>post-integration-test</phase>
             <goals>
                 <goal>stop</goal>
             </goals>
         </execution>
     </executions>
</plugin>

现在我想将 JaCoCo 代理添加到执行中，但将其作为代理或 jvmarguments 添加到配置中不起作用。开始时我总是看到：

[INFO] --- spring-boot-maven-plugin:2.2.4.RELEASE:start (start-spring-boot) @ tosca-ui ---
[INFO] Attaching agents: []

如何将 JaCoCo 与 spring-boot-maven-plugin 一起使用？

Answer 1

By default Spring Boot Maven plugin creates a fork and the agent configuration has to be explicitly specified. It can be done through setting <agents><agent>...</agent></agents> configuration 属性 in Spring Boot Maven plugin BUT it does not work with Jacoco since there is no idiomatic way to find out what's the exact path to the agent jar file.

Instead you can pass argLine variable set by Jacoco to Spring Boot Maven plugin JVM arguments:

<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
    <configuration>
        <jvmArguments>${argLine}</jvmArguments>
    </configuration>
    <executions>
        <execution>
            <id>start-spring-boot</id>
            <phase>pre-integration-test</phase>
            <goals>
                <goal>start</goal>
            </goals>
        </execution>
        <execution>
            <id>stop-spring-boot</id>
            <phase>post-integration-test</phase>
            <goals>
                <goal>stop</goal>
            </goals>
        </execution>
    </executions>
</plugin>

Since quite a few Maven plugins have to be configured to make it work, just to avoid any confusion here's the complete pom.xml file:

    <?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>jacoco-spring-boot-maven</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>jacoco-spring-boot-maven</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>11</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <jvmArguments>${argLine}</jvmArguments>
                </configuration>
                <executions>
                    <execution>
                        <id>start-spring-boot</id>
                        <phase>pre-integration-test</phase>
                        <goals>
                            <goal>start</goal>
                        </goals>
                    </execution>
                    <execution>
                        <id>stop-spring-boot</id>
                        <phase>post-integration-test</phase>
                        <goals>
                            <goal>stop</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-failsafe-plugin</artifactId>
                <version>3.0.0-M4</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>integration-test</goal>
                            <goal>verify</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.jacoco</groupId>
                <artifactId>jacoco-maven-plugin</artifactId>
                <version>0.8.5</version>
                <executions>
                    <execution>
                        <id>default-prepare-agent</id>
                        <goals>
                            <goal>prepare-agent</goal>
                        </goals>
                    </execution>
                    <execution>
                        <id>default-report</id>
                        <phase>verify</phase>
                        <goals>
                            <goal>report</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

With this, once you execute mvn clean verify you can find Jacoco reports in target/site/jacoco/index.html.

You can find complete sample project at jacoco-spring-boot-maven-plugin-sample