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<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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