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@niwasawa

JUnit 5 + Apache Maven による Java の自動テスト導入

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概要

  • JUnit 5 + Apache Maven による Java の自動テストについて基本的なサンプルを書く

今回の環境

  • Java 11 (AdoptOpenJDK 11.0.8+10)
  • JUnit Jupiter 5.7.0
  • Apache Maven 3.6.3
  • Maven Surefire Plugin 3.0.0-M5

JUnit 5 + Apache Maven の基本的なサンプル

ソースコード一覧

├── 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>
      <!-- JUnit 5 でのテスト実行に必要なプラグインを導入 -->
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-surefire-plugin</artifactId>
        <version>3.0.0-M5</version>
      </plugin>
    </plugins>
  </build>

  <dependencies>
    <!-- テストコードの記述に必要なライブラリを導入 -->
    <!-- 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>

参考:

Calc.java

package myapp;

public class Calc {

  private int base;

  // 基準となる値を設定
  public Calc(int base) {
    this.base = base;
  }

  // 足す
  public int plus(int num) {
    return base + num;
  }

  // 引く
  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 {

  // テスト開始前に1回だけ実行される
  @BeforeAll
  static void beforeAll() {
    System.out.println("CalcTest 開始");
  }

  // テスト開始後に1回だけ実行される
  @AfterAll
  static void afterAll() {
    System.out.println("CalcTest 終了");
  }

  // 各テストメソッド開始前に実行される
  @BeforeEach
  void beforeEach() {
    System.out.println("CalcTest のテストメソッドをひとつ開始");
  }

  // 各テストメソッド開始後に実行される
  @AfterEach
  void afterEach() {
    System.out.println("CalcTest のテストメソッドをひとつ終了");
  }

  // テストメソッドは private や static メソッドにしてはいけない
  // 値を返してもいけないので戻り値は void にする
  @Test
  void testPlus() {
    System.out.println("testPlus を実行: 2 + 3 = 5");
    Calc calc = new Calc(2);
    // 第1引数: expected 想定される結果
    // 第2引数: actual 実行結果
    // 第3引数: message 失敗時に出力するメッセージ
    assertEquals(5, calc.plus(3), "2 + 3 = 5 の検証");
  }

  @Test
  void testMinus() {
    System.out.println("testMinus を実行: 5 - 2 = 3");
    Calc calc = new Calc(5);
    assertEquals(3, calc.minus(2), "5 - 2 = 3 の検証");
  }
}

参考:

テスト成功時の例

$ mvn test
[INFO] Scanning for projects...
[INFO] 
[INFO] ---------------------------< mygroup:myapp >----------------------------
[INFO] Building myapp 1.0.0
[INFO] --------------------------------[ jar ]---------------------------------
(中略)
[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
CalcTest 開始
CalcTest のテストメソッドをひとつ開始
testMinus を実行: 5 - 2 = 3
CalcTest のテストメソッドをひとつ終了
CalcTest のテストメソッドをひとつ開始
testPlus を実行: 2 + 3 = 5
CalcTest のテストメソッドをひとつ終了
CalcTest 終了
[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] ------------------------------------------------------------------------

テスト失敗時の例

$ mvn test
[INFO] Scanning for projects...
[INFO] 
[INFO] ---------------------------< mygroup:myapp >----------------------------
[INFO] Building myapp 1.0.0
[INFO] --------------------------------[ jar ]---------------------------------
(中略)
[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
CalcTest 開始
CalcTest のテストメソッドをひとつ開始
testMinus を実行: 5 - 2 = 3
CalcTest のテストメソッドをひとつ終了
CalcTest のテストメソッドをひとつ開始
testPlus を実行: 2 + 3 = 5
CalcTest のテストメソッドをひとつ終了
CalcTest 終了
[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 = 3 の検証 ==> expected: <3> but was: <7>
  at myapp.CalcTest.testMinus(CalcTest.java:53)

[INFO] 
[INFO] Results:
[INFO] 
[ERROR] Failures: 
[ERROR]   CalcTest.testMinus:53 5 - 2 = 3 の検証 ==> expected: <3> but was: <7>
[INFO] 
[ERROR] Tests run: 2, Failures: 1, Errors: 0, Skipped: 0
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------

assertAll でまとめてテストするサンプル

サンプルコード

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);
    // まとめて検証
    // 途中で失敗しても停止せずにすべて検証する
    assertAll(
     () -> assertEquals(30, calc.plus(20)),
     () -> assertEquals(99, calc.plus(90)),
     () -> assertEquals(11, calc.plus(50)),
     () -> assertEquals(40, calc.plus(30))
    );
  }
}

参考:

テスト失敗時の例

$ mvn test
[INFO] Scanning for projects...
[INFO] 
[INFO] ---------------------------< mygroup:myapp >----------------------------
[INFO] Building myapp 1.0.0
[INFO] --------------------------------[ jar ]---------------------------------
(中略)
[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] ------------------------------------------------------------------------

例外発生テストのサンプル

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);
    // 0 で割ったら ArithmeticException が発生することを想定
    ArithmeticException e =
      assertThrows(ArithmeticException.class,
        () -> calc.divide(0));
    assertTrue(e instanceof ArithmeticException);
  }
}

参考資料

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