Maven – JaCoCo代码覆盖率示例

一时失言乱红尘 2023-02-15 05:18 44阅读 0赞

![format_png][]![format_png 1][]

在本文中，我们将向您展示如何使用[JaCoCo Maven插件][JaCoCo Maven]生成Java项目的代码覆盖率报告。

经过测试

1.  Maven 3.5.3
2.  JUnit 5.3.1
3.  jacoco-maven-plugin 0.8.2

> **注意**  
> JaCoCo是一个积极开发的行覆盖率工具，用于测量要测试的代码行数。

## 1. JaCoCo Maven插件 ##

1.1在`pom.xml`文件中声明以下JaCoCo插件。

pom.xml

<plugin>
    		<groupId>org.jacoco</groupId>
    		<artifactId>jacoco-maven-plugin</artifactId>
    		<version>0.8.2</version>
    		<executions>
    			<execution>
    				<goals>
    					<goal>prepare-agent</goal>
    				</goals>
    			</execution>
    			
    			<execution>
    				<id>report</id>
    				<phase>test</phase>
    				<goals>
    					<goal>report</goal>
    				</goals>
    			</execution>
    		</executions>
    	</plugin>

它将在Maven测试阶段运行JaCoCo“报告”目标。

## 2.单元测试 ##

2.1一个简单的Java代码返回一条消息，并检查一个空字符串。

MessageBuilder.java

package com.mkyong.examples;
    
    public class MessageBuilder {
    
        public String getMessage(String name) {
    
            StringBuilder result = new StringBuilder();
    
            if (name == null || name.trim().length() == 0) {
    
                result.append("Please provide a name!");
    
            } else {
    
                result.append("Hello " + name);
    
            }
            return result.toString();
        }
    
    }

2.2上等单元测试。

TestMessageBuilder.java

2.3运行`mvn test` ，将在`target/site/jacoco/*`处生成JaCoCo代码覆盖率报告

Terminal

$ mvn clean test
    
    [INFO] -------------------------------------------------------
    [INFO]  T E S T S
    [INFO] -------------------------------------------------------
    [INFO] Running com.mkyong.examples.TestMessageBuilder
    [INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.012 s - in com.mkyong.examples.TestMessageBuilder
    [INFO]
    [INFO] Results:
    [INFO]
    [INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
    [INFO]
    [INFO]
    [INFO] --- jacoco-maven-plugin:0.8.2:report (report) @ maven-code-coverage ---
    [INFO] Loading execution data file D:\maven-examples\maven-code-coverage\target\jacoco.exec
    [INFO] Analyzed bundle 'maven-code-coverage' with 1 classes
    [INFO] ------------------------------------------------------------------------
    [INFO] BUILD SUCCESS
    [INFO] ------------------------------------------------------------------------
    [INFO] Total time: 4.164 s
    [INFO] Finished at: 2018-11-14T16:48:39+08:00
    [INFO] ------------------------------------------------------------------------

2.4打开`target/site/jacoco/index.html`文件，查看代码覆盖率报告：

![format_png 2][]![format_png 3][]

![format_png 4][]![format_png 5][]

1.  绿色–测试或覆盖代码。
2.  红色–未测试或覆盖代码。
3.  黄色–代码已部分测试或覆盖。

## 3.改进单元测试 ##

3.1为红线再添加一个测试。

TestMessageBuilder.java

package com.mkyong.examples;
    
    import org.junit.jupiter.api.Test;
    
    import static org.junit.jupiter.api.Assertions.assertEquals;
    
    public class TestMessageBuilder {
    
        @Test
        public void testNameMkyong() {
    
            MessageBuilder obj = new MessageBuilder();
            assertEquals("Hello mkyong", obj.getMessage("mkyong"));
    
        }
    
    	@Test
        public void testNameEmpty() {
    
            MessageBuilder obj = new MessageBuilder();
            assertEquals("Please provide a name!", obj.getMessage(" "));
    
        }
    }

再次查看报告。

Terminal

$ mvn clean test

`target/site/jacoco/index.html`

![format_png 6][]![format_png 7][]

3.2如果条件允许，再对黄线添加一项测试。

TestMessageBuilder.java

package com.mkyong.examples;
    
    import org.junit.jupiter.api.Test;
    
    import static org.junit.jupiter.api.Assertions.assertEquals;
    
    public class TestMessageBuilder {
    
        @Test
        public void testNameMkyong() {
    
            MessageBuilder obj = new MessageBuilder();
            assertEquals("Hello mkyong", obj.getMessage("mkyong"));
    
        }
    
        @Test
        public void testNameEmpty() {
    
            MessageBuilder obj = new MessageBuilder();
            assertEquals("Please provide a name!", obj.getMessage(" "));
    
        }
    
        @Test
        public void testNameNull() {
    
            MessageBuilder obj = new MessageBuilder();
            assertEquals("Please provide a name!", obj.getMessage(null));
    
        }
    
    }

再次查看报告。

Terminal

$ mvn clean test

`target/site/jacoco/index.html`

![format_png 8][]![format_png 9][]

![format_png 10][]![format_png 11][]

最后，所有线路均经过测试，覆盖率达到100％。

## 4.常见问题 ##

4.1确保线路覆盖率必须至少达到90％。

pom.xml

<plugin>
    		<groupId>org.jacoco</groupId>
    		<artifactId>jacoco-maven-plugin</artifactId>
    		<version>${jacoco.version}</version>
    		<executions>
    			<execution>
    				<goals>
    					<goal>prepare-agent</goal>
    				</goals>
    			</execution>
    			<execution>
    				<id>jacoco-report</id>
    				<phase>test</phase>
    				<goals>
    					<goal>report</goal>
    				</goals>
    			</execution>
    			
    			<execution>
    				<id>jacoco-check</id>
    				<goals>
    					<goal>check</goal>
    				</goals>
    				<configuration>
    					<rules>
    						<rule>
    							<element>PACKAGE</element>
    							<limits>
    								<limit>
    									<counter>LINE</counter>
    									<value>COVEREDRATIO</value>
    									<minimum>0.9</minimum>
    								</limit>
    							</limits>
    						</rule>
    					</rules>
    				</configuration>
    			</execution>
    			
    		</executions>
    	</plugin>

`jacoco:check`目标已附加到Maven验证阶段。

Terminal

$ mvn clean verify
    
    [INFO] Analyzed bundle 'maven-code-coverage' with 1 classes
    [WARNING] Rule violated for package com.mkyong.examples: lines covered ratio is 0.8, but expected minimum is 0.9

> **注意**  
> 更多[JaCoCo检查][JaCoCo]示例：

4.2如何更新默认的JaCoCo输出文件夹？

pom.xml

## 下载源代码 ##

> $ git clone [https://github.com/mkyong/maven-examples.git][https_github.com_mkyong_maven-examples.git]  
> $ cd maven代码覆盖率
> 
> $ mvn清洁测试  
> ＃在'target / site / jacoco / index.html'查看报告

## 参考文献 ##

1.  [Wikipedia：Java代码覆盖工具][Wikipedia_Java]
2.  [JaCoCo Java代码覆盖率库][JaCoCo Java]
3.  [JaCoCo在Eclipse IDE中][JaCoCo_Eclipse IDE]

标签： [代码覆盖率][Link 1] [jacoco][] [maven][]

> 翻译自: [https://mkyong.com/maven/maven-jacoco-code-coverage-example/][https_mkyong.com_maven_maven-jacoco-code-coverage-example]

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[JaCoCo Maven]: https://www.jacoco.org/jacoco/trunk/doc/maven.html
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[JaCoCo]: https://www.jacoco.org/jacoco/trunk/doc/check-mojo.html
[https_github.com_mkyong_maven-examples.git]: https://github.com/mkyong/maven-examples.git
[Wikipedia_Java]: https://en.wikipedia.org/wiki/Java_code_coverage_tools
[JaCoCo Java]: https://www.jacoco.org/jacoco/
[JaCoCo_Eclipse IDE]: https://www.mkyong.com/maven/jacoco-java-code-coverage-maven-example/
[Link 1]: https://mkyong.com/tag/code-coverage/
[jacoco]: https://mkyong.com/tag/jacoco/
[maven]: https://mkyong.com/tag/maven/
[https_mkyong.com_maven_maven-jacoco-code-coverage-example]: https://mkyong.com/maven/maven-jacoco-code-coverage-example/