Asserting Classes with AssertJ

Table of Contents

介紹 matches 、 satisfies 驗證是否符合條件，類似的流暢或鍊式寫法，語法跟自然語言相近，對於編寫測試時力求容易閱讀及維護這之上提供了相當大的改進， Assert Classes in Java 本篇增加了範例，並透過單元測試來驗證產出結果。

檔案目錄

./
   +- src
       +- test
       |   +- org
       |       +- ruoxue
       |           +- spring_boot_168
       |               +- test
       |                   +- assertj
       |                       +- clazz
       |                           +- AssertingClassesTest.java

單元測試

Assertions Classes in Java 斷言類別的主要目的是取得類別以進行斷言。

Fruit

Assertions Classes in Java 建立 Fruit 類別，覆寫 toString ，定義屬性和方法，用來建立一個物件。

	@NoArgsConstructor
	@Getter
	@Setter
	@Builder
	public static class Fruit {
		private String name;
		private double quantity;
		private int type;

		public Fruit(String name, double quantity, int type) {
			this.name = name;
			this.quantity = quantity;
			this.type = type;
		}

		public String toString() {
			ToStringBuilder builder = new ToStringBuilder(this, ToStringStyle.JSON_STYLE);
			builder.appendSuper(super.toString());
			builder.append("name", name);
			builder.append("quantity", quantity);
			builder.append("type", type);
			return builder.toString();
		}
	}

matches

Assertions Classes in Java 驗證是否符合條件，若不成立，則會拋出 AssertionError 。

	@Test
	public void matches() {
		Class<?> clazz = CharSequence.class;
		System.out.println(clazz);
		assertThat(clazz).matches(c -> c.isInterface());

		Class<?> clazz2 = int.class;
		System.out.println(clazz2);
		assertThat(clazz2).matches(c -> c.isPrimitive());
	}value = "AssertJ";
		System.out.println(value);
		assertThat(value).matches(s -> s.length() < 8);
	}

interface java.lang.CharSequence
int

matchesWithDescription

Assertions Classes in Java 驗證是否符合條件，自訂描述訊息，若不成立，則會拋出 AssertionError 。

	@Test
	public void matchesWithDescription() {
		Class<?> clazz = CharSequence.class;
		System.out.println(clazz);
		assertThat(clazz).matches(c -> c.isInterface(), "interface");

		Class<?> clazz2 = int.class;
		System.out.println(clazz2);
		assertThat(clazz2).matches(c -> c.isPrimitive(), "primitive");
	}

interface java.lang.CharSequence
int

matchesThrowError

Assertions Classes in Java 驗證是否符合條件，自訂描述訊息，當不成立時，驗證拋出 AssertionError 。

	@Test
	public void matchesThrowError() {
		assertThatCode(() -> {
			Class<?> clazz = CharSequence.class;
			System.out.println(clazz);
			assertThat(clazz).matches(c -> c.isPrimitive(), "primitive");
		}).isInstanceOf(AssertionError.class);

		assertThatCode(() -> {
			Class<?> clazz = int.class;
			System.out.println(clazz);
			assertThat(clazz).matches(c -> c.isInterface(), "interface");
		}).isInstanceOf(AssertionError.class);
	}

interface java.lang.CharSequence
int

satisfies

Asserting Classes with Examples 驗證是否符合條件，若不成立，則會拋出 AssertionError 。

	@Test
	public void satisfies() {
		Class<?> clazz = CharSequence.class;
		System.out.println(clazz);
		assertThat(clazz).satisfies(c -> {
			assertThat(c).isInterface();
			assertThat(c).isPublic();
		});

		clazz = int.class;
		System.out.println(clazz);
		assertThat(clazz).satisfies(c -> {
			assertThat(c).isAbstract();
		}, c -> {
			assertThat(c).isFinal();
		});
	}

interface java.lang.CharSequence
int

satisfiesAnyOf

Asserting Classes with Examples 驗證是否符合任一條件，若不成立，則會拋出 AssertionError 。

	@Test
	public void satisfiesAnyOf() {
		Class<?> clazz = CharSequence.class;
		System.out.println(clazz);
		assertThat(clazz).satisfiesAnyOf(c -> {
			assertThat(c).isInterface();
			assertThat(c).isPublic();
		});

		clazz = int.class;
		System.out.println(clazz);
		assertThat(clazz).satisfiesAnyOf(c -> {
			assertThat(c).isAbstract();
		}, c -> {
			assertThat(c).isAnnotation();
		});
	}

interface java.lang.CharSequence
int

satisfiesThrowError

Asserting Classes with Examples 驗證是否符合條件，當不成立時，驗證拋出 AssertionError 。

	@Test
	public void satisfiesThrowError() {
		assertThatCode(() -> {
			Class<?> clazz = CharSequence.class;
			System.out.println(clazz);
			assertThat(clazz).satisfies(c -> {
				assertThat(c).isInterface();
				assertThat(c).isProtected();
			});
		}).isInstanceOf(AssertionError.class);

		assertThatCode(() -> {
			Class<?> clazz = int.class;
			System.out.println(clazz);
			assertThat(clazz).satisfies(c -> {
				assertThat(c).isAbstract();
			}, c -> {
				assertThat(c).isAnnotation();
			});
		}).isInstanceOf(AssertionError.class);
	}

interface java.lang.CharSequence
int

AssertingClassesTest.java

Asserting Classes with Examples 新增單元測試，驗證是否符合預期。

package org.ruoxue.spring_boot_168.test.assertj.clazz;

import static org.assertj.core.api.Assertions.*;

import org.apache.commons.lang3.builder.ToStringBuilder;
import org.apache.commons.lang3.builder.ToStringStyle;
import org.junit.jupiter.api.Test;

import lombok.Builder;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

public class AssertingClassesTest {

	@NoArgsConstructor
	@Getter
	@Setter
	@Builder
	public static class Fruit {
		private String name;
		private double quantity;
		private int type;

		public Fruit(String name, double quantity, int type) {
			this.name = name;
			this.quantity = quantity;
			this.type = type;
		}

		public String toString() {
			ToStringBuilder builder = new ToStringBuilder(this, ToStringStyle.JSON_STYLE);
			builder.appendSuper(super.toString());
			builder.append("name", name);
			builder.append("quantity", quantity);
			builder.append("type", type);
			return builder.toString();
		}
	}

	@Test
	public void matches() {
		Class<?> clazz = CharSequence.class;
		System.out.println(clazz);
		assertThat(clazz).matches(c -> c.isInterface());

		Class<?> clazz2 = int.class;
		System.out.println(clazz2);
		assertThat(clazz2).matches(c -> c.isPrimitive());
	}

	@Test
	public void matchesWithDescription() {
		Class<?> clazz = CharSequence.class;
		System.out.println(clazz);
		assertThat(clazz).matches(c -> c.isInterface(), "interface");

		Class<?> clazz2 = int.class;
		System.out.println(clazz2);
		assertThat(clazz2).matches(c -> c.isPrimitive(), "primitive");
	}

	@Test
	public void matchesThrowError() {
		assertThatCode(() -> {
			Class<?> clazz = CharSequence.class;
			System.out.println(clazz);
			assertThat(clazz).matches(c -> c.isPrimitive(), "primitive");
		}).isInstanceOf(AssertionError.class);

		assertThatCode(() -> {
			Class<?> clazz = int.class;
			System.out.println(clazz);
			assertThat(clazz).matches(c -> c.isInterface(), "interface");
		}).isInstanceOf(AssertionError.class);
	}

	@Test
	public void satisfies() {
		Class<?> clazz = CharSequence.class;
		System.out.println(clazz);
		assertThat(clazz).satisfies(c -> {
			assertThat(c).isInterface();
			assertThat(c).isPublic();
		});

		clazz = int.class;
		System.out.println(clazz);
		assertThat(clazz).satisfies(c -> {
			assertThat(c).isAbstract();
		}, c -> {
			assertThat(c).isFinal();
		});
	}

	@Test
	public void satisfiesAnyOf() {
		Class<?> clazz = CharSequence.class;
		System.out.println(clazz);
		assertThat(clazz).satisfiesAnyOf(c -> {
			assertThat(c).isInterface();
			assertThat(c).isPublic();
		});

		clazz = int.class;
		System.out.println(clazz);
		assertThat(clazz).satisfiesAnyOf(c -> {
			assertThat(c).isAbstract();
		}, c -> {
			assertThat(c).isAnnotation();
		});
	}

	@Test
	public void satisfiesThrowError() {
		assertThatCode(() -> {
			Class<?> clazz = CharSequence.class;
			System.out.println(clazz);
			assertThat(clazz).satisfies(c -> {
				assertThat(c).isInterface();
				assertThat(c).isProtected();
			});
		}).isInstanceOf(AssertionError.class);

		assertThatCode(() -> {
			Class<?> clazz = int.class;
			System.out.println(clazz);
			assertThat(clazz).satisfies(c -> {
				assertThat(c).isAbstract();
			}, c -> {
				assertThat(c).isAnnotation();
			});
		}).isInstanceOf(AssertionError.class);
	}
}

心得分享

Testing Java Classes with AssertJ 快速檢查物件是否滿足所有提供的斷言，搭配使用 Predicate 與 ThrowingConsumer 等接口，根據 lambda 表達式調用，驗證是否成立，若不成立，則會拋出 AssertionError， Asserting Classes with Examples 介紹 matches 、 satisfies 等方法，提供範例參考。