一.Hamcrest是什么？

Hamcrest is a library of matchers, which can be combined in to create flexible expressions of intent in tests.
Hamcrest 是一个为了测试为目的，且能组合成灵活表达式的匹配器类库。

二.Hamcrest jar包

hamcrest-core.jar -- This is the core API to be used by third-party framework providers. This includes the a foundation set of matcher implementations for common operations. This API is stable and will rarely change. You will need this library as a minimum.
hamcrest-library.jar -- The ever-growing library of Matcher implementations. This will grow between releases.
hamcrest-generator.jar -- A tool to allow many Matcher implementations to be combined into a single class so users don't have to remember many classes/packages to import. Generates code.
hamcrest-integration.jar -- Provides integration between Hamcrest and other testing tools, including JUnit (3 and 4), TestNG, jMock and EasyMock.
Alternatively, if you don't care:

hamcrest-all.jar -- Includes all of the above.
三.常用方法介绍
一般，在项目中导入hamcrest-core.jar， hamcrest-library.jar就能满足使用。
Eclipse新建一个JUnit test case； 测试类导入
import static org.hamcrest.Matchers.*;
测试方法如下：

import static org.hamcrest.Matchers.*;
import static org.junit.Assert.*;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import org.junit.Test;/*** Hamcrest演示.<br>* @author gongqiang <br>* @version 1.0.0 2021年6月16日<br>* @see * @since JDK 1.5.0*/
public class HamcrestDemo {/*** 核心匹配.*/@Testpublic void coreMatcher() {// allOf: 所有条件都必须满足，相当于&&assertThat("myname", allOf(startsWith("my"), containsString("name")));// anyOf: 其中一个满足就通过， 相当于||assertThat("myname", anyOf(startsWith("na"), containsString("name")));// both: &&assertThat("myname", both(containsString("my")).and(containsString("me")));// either: 两者之一assertThat("myname", either(containsString("my")).or(containsString("you")));// everyItem: 每个元素都需满足特定条件assertThat(Arrays.asList("my", "mine"), everyItem(startsWith("m")));// hasItem: 是否有这个元素assertThat(Arrays.asList("my", "mine"), hasItem("my"));// hasItems: 包含多个元素assertThat(Arrays.asList("my", "mine", "your"), hasItems("your", "my"));// is: is(equalTo(x))或is(instanceOf(clazz.class))的简写assertThat("myname", is("myname"));assertThat("myname", is(equalTo("myname")));//assertThat("mynmae", is(String.class));assertThat("mynmae", is(instanceOf(String.class))); // 简写运行异常，需要补全.// anything(): 任何情况下，都匹配正确assertThat("myname", anything());// not: 否为真，相当于！assertThat("myname", is(not("you")));// nullValue(): 值为空String str = null;assertThat(str, is(nullValue()));// notNullValue(): 值不为空String str2 = "123";assertThat(str2, is(notNullValue()));}/*** 字符串匹配.*/@Testpublic void stringMatcher() {// containsString：包含字符串assertThat("myname", containsString("na"));// stringContainsInOrder: 顺序包含，“my”必须在“me”前面assertThat("myname", stringContainsInOrder(Arrays.asList("my", "me")));// endsWith: 后缀assertThat("myname", endsWith("me"));// startsWith: 前缀assertThat("myname", startsWith("my"));// emptyString(): 空字符串assertThat("", emptyString());// equalTo: 值相等， Object.equals(Object)assertThat("myname", equalTo("myname"));assertThat(new String[] {"a", "b"}, equalTo(new String[] {"a", "b"}));// equalToIgnoringCase: 比较时，忽略大小写assertThat("myname", equalToIgnoringCase("MYNAME"));// equalToCompressingWhiteSpace: 比较时， 首尾空格忽略， 比较时中间用单个空格assertThat(" my \t name ", equalToCompressingWhiteSpace(" my name "));// oneOf: 是否为其中之一assertThat("myname", oneOf("myname", "yourname"));// in: 是否为其成员assertThat("myname", in(new String[]{"myname", "yourname"}));// toString() 返回值校验assertThat(333, hasToString(equalTo("333")));}/*** 数值匹配.*/@Testpublic void numberMatcher() {// closeTo: [operand-error, operand+error], Double或BigDecimal类型assertThat(3.14, closeTo(3, 0.5));assertThat(new BigDecimal("3.14"), is(closeTo(new BigDecimal("3"), new BigDecimal("0.5"))));// comparesEqualTo: compareTo比较值assertThat(2, comparesEqualTo(2));// greaterThan： 大于assertThat(2, greaterThan(0));// greaterThanOrEqualTo: 大于等于assertThat(2, greaterThanOrEqualTo(2));// lessThan: 小于assertThat(0, lessThan(2));// lessThanOrEqualTo: 小于等于assertThat(0, lessThanOrEqualTo(0));}/*** 集合匹配*/@Testpublic void collectionMatcher() {// array: 数组长度相等且对应元素也相等assertThat(new Integer[]{1, 2, 3}, is(array(equalTo(1), equalTo(2), equalTo(3))));// hasItemInArray: 数组是否包含特定元素assertThat(new String[]{"my", "you"}, hasItemInArray(startsWith("y")));// arrayContainingInAnyOrder， 顺序无关，长度要一致assertThat(new String[]{"my", "you"}, arrayContainingInAnyOrder("you", "my"));// arrayContaining:  顺序，长度一致assertThat(new String[]{"my", "you"}, arrayContaining("my", "you"));// arrayWithSize: 数组长度assertThat(new String[]{"my", "you"}, arrayWithSize(2));// emptyArray: 空数组assertThat(new String[0], emptyArray());// hasSize: 集合大小assertThat(Arrays.asList("my", "you"), hasSize(equalTo(2)));// empty: 空集合assertThat(new ArrayList<String>(), empty());assertThat(new ArrayList<String>(), is(empty()));// in: 是否为集合成员assertThat("myname", in(Arrays.asList("myname", "yourname")));assertThat("myname", is(in(Arrays.asList("myname", "yourname"))));// Map匹配Map<String, String> myMap = new HashMap<String, String>();myMap.put("name", "john");// hasEntry: key && value匹配assertThat(myMap, hasEntry("name", "john"));// hasKey: key匹配assertThat(myMap, hasKey(equalTo("name")));// hasValue: value匹配assertThat(myMap, hasValue(equalTo("john")));}
}

原文链接：https://blog.csdn.net/neven7/article/details/42489723