--Write a basic sample of Java automated testing with JUnit 5 + Gradle
--JUnit is a Java automated testing framework
├── build.gradle
├── settings.gradle
└── src
├── main
│ └── java
│ └── myapp
│ └── Calc.java
└── test
└── java
└── myapp
└── CalcTest.java
build.gradle
build.gradle
plugins {
id 'java'
}
repositories {
jcenter()
}
dependencies {
// Junit Jupiter 5.5.Introduced 2
//The following are introduced as dependencies
// junit-jupiter-api:5.5.2
// junit-jupiter-engine:5.5.2
// junit-jupiter-platform-engine:1.5.2
testImplementation 'org.junit.jupiter:junit-jupiter:5.5.2'
}
test {
//Settings to use JUnit platform
useJUnitPlatform()
testLogging {
//Display standard output and standard error output during testing
showStandardStreams true
//Output event(TestLogEvent)
events 'started', 'skipped', 'passed', 'failed'
//Output settings when an exception occurs(TestExceptionFormat)
exceptionFormat 'full'
}
}
reference:
settings.gradle
settings.gradle
rootProject.name = 'myapp'
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 only once before starting each test method
@BeforeEach
void beforeEach() {
System.out.println("Start one test method of CalcTest");
}
//Executed only once 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:
$ gradle test
> Task :test
myapp.CalcTest STANDARD_OUT
Start CalcTest
myapp.CalcTest > testMinus() STARTED
myapp.CalcTest > testMinus() STANDARD_OUT
Start one test method of CalcTest
Run testMinus: 5 - 2 = 3
Finish one test method of CalcTest
myapp.CalcTest > testMinus() PASSED
myapp.CalcTest > testPlus() STARTED
myapp.CalcTest > testPlus() STANDARD_OUT
Start one test method of CalcTest
Run testPlus: 2 + 3 = 5
Finish one test method of CalcTest
myapp.CalcTest > testPlus() PASSED
myapp.CalcTest STANDARD_OUT
CalcTest finished
BUILD SUCCESSFUL in 1s
3 actionable tasks: 3 executed
$ gradle test
> Task :test FAILED
myapp.CalcTest STANDARD_OUT
Start CalcTest
myapp.CalcTest > testMinus() STARTED
myapp.CalcTest > testMinus() STANDARD_OUT
Start one test method of CalcTest
Run testMinus: 5 - 2 = 3
Finish one test method of CalcTest
myapp.CalcTest > testMinus() FAILED
org.opentest4j.AssertionFailedError: 5 - 2 =Verification of 3==> expected: <3> but was: <7>
at org.junit.jupiter.api.AssertionUtils.fail(AssertionUtils.java:55)
at org.junit.jupiter.api.AssertionUtils.failNotEqual(AssertionUtils.java:62)
at org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:150)
at org.junit.jupiter.api.Assertions.assertEquals(Assertions.java:542)
at myapp.CalcTest.testMinus(CalcTest.java:48)
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 it fails 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:
$ gradle test
> Task :test FAILED
myapp.CalcTest > testPlus() STARTED
myapp.CalcTest > testPlus() FAILED
org.opentest4j.MultipleFailuresError: Multiple Failures (2 failures)
org.opentest4j.AssertionFailedError: expected: <99> but was: <100>
org.opentest4j.AssertionFailedError: expected: <11> but was: <60>
at org.junit.jupiter.api.AssertAll.assertAll(AssertAll.java:80)
at org.junit.jupiter.api.AssertAll.assertAll(AssertAll.java:44)
at org.junit.jupiter.api.AssertAll.assertAll(AssertAll.java:38)
at org.junit.jupiter.api.Assertions.assertAll(Assertions.java:2839)
at myapp.CalcTest.testPlus(CalcTest.java:15)
1 test completed, 1 failed
FAILURE: Build failed with an exception.
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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