【单元测试】Junit 4(八)--junit4 内置Rule
1.0 Rules
Rules允许非常灵活地添加或重新定义一个测试类中每个测试方法的行为。测试人员可以重复使用或扩展下面提供的Rules之一,或编写自己的Rules。
1.1 TestName
TestName Rule使当前的测试名称在测试方法中可用。用于在测试执行过程中获取测试方法名称。在starting()中记录测试方法名,在getMethodName()中返回
例如:
import static org.junit.Assert.*;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TestName;
public class NameRuleTest {
@Rule
public final TestName name = new TestName();
@Test
public void testA() {
assertEquals("testA", name.getMethodName());
}
@Test
public void testB() {
assertEquals("testB", name.getMethodName());
}
}
1.2 TemporaryFolder
TemporaryFolder Rule允许创建文件和文件夹,这些文件和文件夹在测试方法结束时被删除(无论通过还是失败)。默认情况下,如果资源不能被删除,则不会抛出异常。
import java.io.*;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TemporaryFolder;
public class HasTempFolder {
@Rule
public TemporaryFolder folder= new TemporaryFolder();
@Test
public void testUsingTempFolder() throws IOException {
File createdFile = folder.newFile("myfile.txt");
File createdFolder = folder.newFolder("subfolder");
// ...
}
}
- TemporaryFolder#newFolder(String... folderNames)可以根据输入的参数创建目录。如果是多级目录,可以递归创建。
- TemporaryFolder#newFile()可以创建一个随机名字的临时文件;
- TemporaryFolder##newFolder() 可以创建一个随机名字的临时目录。
1.3 ExternalResource
ExternalResource是一个规则(如TemporaryFolder)的基类,它在测试前设置了一个外部资源(一个文件、套接字、服务器、数据库连接等),并保证在测试后将其拆除。
可以设置测试前后需要做的事情(比如:文件、socket、服务、数据库的连接与关闭)。
public static class UsesExternalResource {
Server myServer = new Server();
@Rule
public ExternalResource resource = new ExternalResource() {
@Override
protected void before() throws Throwable {
myServer.connect();
};
@Override
protected void after() {
myServer.disconnect();
};
};
@Test
public void testFoo() {
new Client().run(myServer);
}
}
- ExternalResource#before会在每个测试之前处理;#after会在每个测试之后处理;
- 关于ExternalResource与@Before已经@After等标记步骤的执行顺序,我们会在本文后面部分介绍。
1.4 ErrorCollector
ErrorCollector这个Rule,在出现一个错误后,还可以让测试继续进行下去。
他提供三个方法:
- checkThat(final T value, Matcher
matcher) - checkSucceeds(Callable
- addError(Throwable error)
前面两个是用来处理断言的,最后一个是添加错误至错误列表中。
看下面例子:
package mytest;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;
import java.util.concurrent.Callable;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ErrorCollector;
public class JUnitCoreErrorControllerRuleTest {
private final int multiplesOf2[] = { 0, 2, 4, 7, 8, 11, 12 };
@Rule
public ErrorCollector errorCollector = new ErrorCollector();
/*
* 下面这个测试,会报告两个failures。这一点和下面的checkSucceeds测试不同
*/
@Test
public void testMultiplesOf2() {
int multiple = 0;
for (int multipleOf2 : multiplesOf2) {
// Will count the number of issues in this list
// - 3*2 = 6 not 7, 5*2 = 10 not 11 : 2 Failures
errorCollector.checkThat(2 * multiple, is(multipleOf2));
multiple++;
}
}
/*
* 下面代码中有两个断言会失败,但每次运行JUnit框架只会报告一个。这一点和上面的checkThat测试不同,可以对比一下。
*/
@Test
public void testCallableMultiples() {
errorCollector.checkSucceeds(new Callable<Object>() {
public Object call() throws Exception {
assertThat(2 * 2, is(5));
assertThat(2 * 3, is(6));
assertThat(2 * 4, is(8));
assertThat(2 * 5, is(9));
return null;
}
});
}
/*
* 下面运行时,会报告2个错误
*/
@Test
public void testAddingAnError() {
assertThat(2 * 2, is(4));
errorCollector.addError(new Throwable("Error Collector added an error"));
assertThat(2 * 3, is(6));
errorCollector.addError(new Throwable(
"Error Collector added a second error"));
}
}
运行结果:
Failed tests:
testCallableMultiples(mytest.JUnitCoreErrorControllerRuleTest):
Expected: is <5>
but: was <4>
testMultiplesOf2(mytest.JUnitCoreErrorControllerRuleTest):
Expected: is <7>
but: was <6>
testMultiplesOf2(mytest.JUnitCoreErrorControllerRuleTest):
Expected: is <11>
but: was <10>
Tests in error:
testAddingAnError(tangzhi.mytest.JUnitCoreErrorControllerRuleTest): Error Collector added an error
testAddingAnError(tangzhi.mytest.JUnitCoreErrorControllerRuleTest): Error Collector added a second error
从这个例子,可以看出:
- ErrorCollector#checkThat 会报告测试中的每一个failures
- ErrorCollector#checkSucceeds 只会检查是否成功,如果不成功,只报告第一个导致不成功的failure
- ErrorCollector#addError 是添加一个错误(error)。
1.5 Verifier
如果,你想在每个测试之后,甚至是在@After之后,想检查些什么,就可以使用Verifier这个Rule.
看例子:
private static String sequence;
public static class UsesVerifier {
@Rule
public Verifier collector = new Verifier() {
@Override
protected void verify() {
sequence += " verify ";
}
};
@Test
public void example() {
sequence += "test";
}
@Test
public void example2() {
sequence += "test2";
}
@After
public void after() {
sequence += " after";
}
}
@Test
public void verifierRunsAfterTest() {
sequence = "";
assertThat(testResult(UsesVerifier.class), isSuccessful());
assertEquals("test after verify test2 after verify ", sequence);
}
从上面例子可以看出:Verifier#verify针对每个测试都会运行一次,并且运行在@After步骤之后。
需要说明:如果某测试出现失败(fail),那么这个测试之后就不会做verify,这一点,可以结合下面的例子看出
1.6 TestWatcher
对测试的每个步骤进行监控。
看例子:
package tangzhi.mytest;
import static org.junit.Assert.*;
import static org.hamcrest.CoreMatchers.*;
import org.junit.After;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TestRule;
import org.junit.rules.TestWatcher;
import org.junit.rules.Verifier;
import org.junit.runner.Description;
import org.junit.runners.model.Statement;
public class WatchmanTest {
private static String watchedLog;
@Rule
public TestRule watchman = new TestWatcher() {
@Override
public Statement apply(Statement base, Description description) {
Statement s = super.apply(base, description);
watchedLog="";
System.out.println("watch apply.");
return s;
}
@Override
protected void succeeded(Description description) {
watchedLog += description.getDisplayName() + " " + "success!";
System.out.println("watch succeed:"+watchedLog);
}
@Override
protected void failed(Throwable e, Description description) {
watchedLog += description.getDisplayName() + " " + e.getClass().getSimpleName();
System.out.println("watch failed:"+watchedLog);
}
@Override
protected void starting(Description description) {
super.starting(description);
System.out.println("watch starting.");
}
@Override
protected void finished(Description description) {
super.finished(description);
System.out.println("watch finished.");
}
};
@Rule
public Verifier collector = new Verifier() {
@Override
protected void verify() {
System.out.println("@Verify:"+watchedLog);
}
};
@Test
public void fails() {
System.out.println("in fails");
assertThat("ssss", is("sss"));
}
@Test
public void succeeds() {
System.out.println("in succeeds");
}
@After
public void after() {
System.out.println("@After");
}
}
1.7 Timeout
对于添加了TimeoutRule 的测试类,当测试类中的测试方法执行超过TimeoutRule 配置的时间时,测试方法执行就会被标记为失败
public class TimeoutRuleTest {
@Rule
public Timeout globalTimeout = Timeout.seconds(5);
@Test
public void timeout() throws InterruptedException {
TimeUnit.SECONDS.sleep(10);
}
@Test
public void onTime() throws InterruptedException {
TimeUnit.SECONDS.sleep(2);
}
}
执行上面测试用例,onTime方法执行通过,timeout()方法则抛出TestTimedOutException:
org.junit.runners.model.TestTimedOutException: test timed out after 5 seconds
还有很多Rule就不一一介绍了
本文来自博客园,作者:还梦呦,转载请注明原文链接:https://www.cnblogs.com/hmy71/p/junit_8.html