--Write a basic sample of Java automated testing with JUnit 5 + Apache Maven
├── pom.xml
└── src
├── main
│ └── java
│ └── myapp
│ └── Calc.java
└── test
└── java
└── myapp
└── CalcTest.java
pom.xml
<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 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>mygroup</groupId>
<artifactId>myapp</artifactId>
<packaging>jar</packaging>
<version>1.0.0</version>
<name>myapp</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>11</maven.compiler.source>
<maven.compiler.target>11</maven.compiler.target>
</properties>
<build>
<plugins>
<!--Introduced the plugin required for test execution in JUnit 5-->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>3.0.0-M5</version>
</plugin>
</plugins>
</build>
<dependencies>
<!--Introduced the library required for writing test code-->
<!-- https://mvnrepository.com/artifact/org.junit.jupiter/junit-jupiter-api -->
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<version>5.7.0</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>
reference:
Calc.java
package myapp;
public class Calc {
private int base;
//Set a reference value
public Calc(int base) {
this.base = base;
}
//Add
public int plus(int num) {
return base + num;
}
//Pull
public int minus(int num) {
return base - num;
}
}
CalcTest.java
package myapp;
import org.junit.jupiter.api.AfterAll;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;
class CalcTest {
//Run only once before the test starts
@BeforeAll
static void beforeAll() {
System.out.println("Start CalcTest");
}
//Run only once after the test starts
@AfterAll
static void afterAll() {
System.out.println("CalcTest finished");
}
//Executed before each test method starts
@BeforeEach
void beforeEach() {
System.out.println("Start one test method of CalcTest");
}
//Executed after each test method starts
@AfterEach
void afterEach() {
System.out.println("Finish one test method of CalcTest");
}
//Test methods should not be private or static methods
//The return value should be void because the value cannot be returned.
@Test
void testPlus() {
System.out.println("Run testPlus: 2 + 3 = 5");
Calc calc = new Calc(2);
//1st argument:expected expected result
//2nd argument:actual execution result
//3rd argument:message Output message when failure
assertEquals(5, calc.plus(3), "2 + 3 =Verification of 5");
}
@Test
void testMinus() {
System.out.println("Run testMinus: 5 - 2 = 3");
Calc calc = new Calc(5);
assertEquals(3, calc.minus(2), "5 - 2 =Verification of 3");
}
}
reference:
$ mvn test
[INFO] Scanning for projects...
[INFO]
[INFO] ---------------------------< mygroup:myapp >----------------------------
[INFO] Building myapp 1.0.0
[INFO] --------------------------------[ jar ]---------------------------------
(Omission)
[INFO] --- maven-surefire-plugin:3.0.0-M5:test (default-test) @ myapp ---
[INFO]
[INFO] -------------------------------------------------------
[INFO] T E S T S
[INFO] -------------------------------------------------------
[INFO] Running myapp.CalcTest
Start CalcTest
Start one test method of CalcTest
Run testMinus: 5 - 2 = 3
Finish one test method of CalcTest
Start one test method of CalcTest
Run testPlus: 2 + 3 = 5
Finish one test method of CalcTest
CalcTest finished
[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.087 s - in myapp.CalcTest
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
$ mvn test
[INFO] Scanning for projects...
[INFO]
[INFO] ---------------------------< mygroup:myapp >----------------------------
[INFO] Building myapp 1.0.0
[INFO] --------------------------------[ jar ]---------------------------------
(Omission)
[INFO] --- maven-surefire-plugin:3.0.0-M5:test (default-test) @ myapp ---
[INFO]
[INFO] -------------------------------------------------------
[INFO] T E S T S
[INFO] -------------------------------------------------------
[INFO] Running myapp.CalcTest
Start CalcTest
Start one test method of CalcTest
Run testMinus: 5 - 2 = 3
Finish one test method of CalcTest
Start one test method of CalcTest
Run testPlus: 2 + 3 = 5
Finish one test method of CalcTest
CalcTest finished
[ERROR] Tests run: 2, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 0.063 s <<< FAILURE! - in myapp.CalcTest
[ERROR] myapp.CalcTest.testMinus Time elapsed: 0.026 s <<< FAILURE!
org.opentest4j.AssertionFailedError: 5 - 2 =Verification of 3==> expected: <3> but was: <7>
at myapp.CalcTest.testMinus(CalcTest.java:53)
[INFO]
[INFO] Results:
[INFO]
[ERROR] Failures:
[ERROR] CalcTest.testMinus:53 5 - 2 =Verification of 3==> expected: <3> but was: <7>
[INFO]
[ERROR] Tests run: 2, Failures: 1, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
package myapp;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertAll;
import static org.junit.jupiter.api.Assertions.assertEquals;
class CalcTest {
@Test
void testPlus() {
Calc calc = new Calc(10);
//Collectively verify
//Even if you fail in the middle, verify everything without stopping
assertAll(
() -> assertEquals(30, calc.plus(20)),
() -> assertEquals(99, calc.plus(90)),
() -> assertEquals(11, calc.plus(50)),
() -> assertEquals(40, calc.plus(30))
);
}
}
reference:
$ mvn test
[INFO] Scanning for projects...
[INFO]
[INFO] ---------------------------< mygroup:myapp >----------------------------
[INFO] Building myapp 1.0.0
[INFO] --------------------------------[ jar ]---------------------------------
(Omission)
[INFO] --- maven-surefire-plugin:3.0.0-M5:test (default-test) @ myapp ---
[INFO]
[INFO] -------------------------------------------------------
[INFO] T E S T S
[INFO] -------------------------------------------------------
[INFO] Running myapp.CalcTest
[ERROR] Tests run: 1, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 0.067 s <<< FAILURE! - in myapp.CalcTest
[ERROR] myapp.CalcTest.testPlus Time elapsed: 0.044 s <<< FAILURE!
org.opentest4j.MultipleFailuresError:
Multiple Failures (2 failures)
org.opentest4j.AssertionFailedError: expected: <99> but was: <100>
org.opentest4j.AssertionFailedError: expected: <11> but was: <60>
at myapp.CalcTest.testPlus(CalcTest.java:15)
[INFO]
[INFO] Results:
[INFO]
[ERROR] Failures:
[ERROR] CalcTest.testPlus:15 Multiple Failures (2 failures)
org.opentest4j.AssertionFailedError: expected: <99> but was: <100>
org.opentest4j.AssertionFailedError: expected: <11> but was: <60>
[INFO]
[ERROR] Tests run: 1, Failures: 1, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
package myapp;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.fail;
class CalcTest {
@Test
void testPlus() {
Calc calc = new Calc(100);
//Assuming an ArithmeticException will occur if divided by 0
ArithmeticException e =
assertThrows(ArithmeticException.class,
() -> calc.divide(0));
assertTrue(e instanceof ArithmeticException);
}
}
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