JUnit4---Hamcrest匹配器常用方法总结

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：

    @Test
    public 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(), is(empty()));
        // isIn: 是否为集合成员
        assertThat("myname", isIn(Arrays.asList("myname", "yourname")));
       // Map匹配
        Map myMap = new HashMap();
        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")));
    }