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：

@Testpublic void testHamcrestMatchers() { // 核心匹配 // 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("mynmae", is(String.class)); // 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 // 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")); // isEmptyString(): 空字符串 assertThat("", isEmptyString()); // 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")); // equalToIgnoringWhiteSpace: 比较时， 首尾空格忽略， 比较时中间用单个空格 assertThat(" my t name ", equalToIgnoringWhiteSpace(" my name ")); // isOneOf: 是否为其中之一 assertThat("myname", isOneOf("myname", "yourname")); // isIn: 是否为其成员 assertThat("myname", isIn(new String[]{ "myname", "yourname" } )); // toString() 返回值校验 assertThat(333, hasToString(equalTo("333"))); // 数值匹配 // 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 // 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>(), is(empty())); // isIn: 是否为集合成员 assertThat("myname", isIn(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")));}

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