How to conduct code testing and code coverage checking in Java development

How to conduct code testing and code coverage checking in Java development

In the Java development process, code testing and code coverage checking are very important links. Code testing can help developers discover and eliminate potential bugs and ensure code quality and stability; while code coverage inspection can evaluate the completeness of tests and ensure that tests cover as much code as possible. This article will introduce how to conduct Java code testing and code coverage checking, and provide specific code examples.

1. Code testing

Code testing can generally be divided into unit testing, integration testing and system testing. Among them, unit testing is the most basic testing level, which focuses on testing a single class or method. A sample code is given below to demonstrate how to use JUnit for unit testing.

import org.junit.Test;
import static org.junit.Assert.*;

public class CalculatorTest {
    
    @Test
    public void addTest() {
        Calculator calculator = new Calculator();
        assertEquals(5, calculator.add(2, 3));
    }
    
    @Test
    public void subtractTest() {
        Calculator calculator = new Calculator();
        assertEquals(1, calculator.subtract(3, 2));
    }
}

In the example, a Calculator class is created, which includes two methods: add and subtract. Use JUnit's @Test annotation to mark the test method, and use the assertEquals method in the method to compare the actual results with the expected results. If the two match, the test passes; otherwise, the test fails.

In addition to JUnit, there are other popular Java testing frameworks, such as TestNG, Mockito, etc. Developers can choose the appropriate testing framework according to their own needs.

2. Code coverage check

Code coverage check can help developers evaluate the completeness of tests and can usually be divided into three levels: statement coverage, branch coverage and path coverage. Using code coverage tools can help developers check whether tests cover various parts of the code. A sample code is given below to demonstrate how to use JaCoCo for code coverage checking.

First, you need to add the dependency of the JaCoCo plug-in in the pom.xml file:

<build>
    <plugins>
        <plugin>
            <groupId>org.jacoco</groupId>
            <artifactId>jacoco-maven-plugin</artifactId>
            <version>0.8.7</version>
            <executions>
                <execution>
                    <id>default-prepare-agent</id>
                    <goals>
                        <goal>prepare-agent</goal>
                    </goals>
                </execution>
                <execution>
                    <id>default-report</id>
                    <phase>prepare-package</phase>
                    <goals>
                        <goal>report</goal>
                    </goals>
                </execution>
                <execution>
                    <id>default-check</id>
                    <goals>
                        <goal>check</goal>
                    </goals>
                    <configuration>
                        <rules>
                            <rule>
                                <element>PACKAGE</element>
                                <limits>
                                    <limit>
                                        <counter>BRANCH</counter>
                                        <value>COVEREDRATIO</value>
                                        <minimum>0.8</minimum>
                                    </limit>
                                </limits>
                            </rule>
                        </rules>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

Then, run the following command in the root directory of the project to generate a test report:

mvn clean test

After executing the above command, you can view the code coverage report in target/site/jacoco/index.html.

3. Summary

Code testing and code coverage checking are indispensable links in Java development. With the right testing framework and code coverage tools, code quality and stability can be effectively improved. This article takes JUnit and JaCoCo as examples and gives specific code examples, hoping to provide some reference and help to Java developers when conducting code testing and code coverage checks.

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