如何使用JUnit测试触发异步进程的方法?
我不知道如何让我的测试等待流程结束(它不是一个确切的单元测试,它更像一个集成测试,因为它涉及到几个类,而不仅仅是一个)。
如何使用JUnit测试触发异步进程的方法?
我不知道如何让我的测试等待流程结束(它不是一个确切的单元测试,它更像一个集成测试,因为它涉及到几个类,而不仅仅是一个)。
当前回答
如果你想测试逻辑,不要异步测试。
例如,测试这段代码,它对异步方法的结果起作用。
public class Example {
private Dependency dependency;
public Example(Dependency dependency) {
this.dependency = dependency;
}
public CompletableFuture<String> someAsyncMethod(){
return dependency.asyncMethod()
.handle((r,ex) -> {
if(ex != null) {
return "got exception";
} else {
return r.toString();
}
});
}
}
public class Dependency {
public CompletableFuture<Integer> asyncMethod() {
// do some async stuff
}
}
在测试中模拟使用同步实现的依赖关系。单元测试是完全同步的,运行时间为150毫秒。
public class DependencyTest {
private Example sut;
private Dependency dependency;
public void setup() {
dependency = Mockito.mock(Dependency.class);;
sut = new Example(dependency);
}
@Test public void success() throws InterruptedException, ExecutionException {
when(dependency.asyncMethod()).thenReturn(CompletableFuture.completedFuture(5));
// When
CompletableFuture<String> result = sut.someAsyncMethod();
// Then
assertThat(result.isCompletedExceptionally(), is(equalTo(false)));
String value = result.get();
assertThat(value, is(equalTo("5")));
}
@Test public void failed() throws InterruptedException, ExecutionException {
// Given
CompletableFuture<Integer> c = new CompletableFuture<Integer>();
c.completeExceptionally(new RuntimeException("failed"));
when(dependency.asyncMethod()).thenReturn(c);
// When
CompletableFuture<String> result = sut.someAsyncMethod();
// Then
assertThat(result.isCompletedExceptionally(), is(equalTo(false)));
String value = result.get();
assertThat(value, is(equalTo("got exception")));
}
}
你不测试异步行为,但你可以测试逻辑是否正确。
其他回答
调用SomeObject怎么样?或者使用Robotiums Solo.waitForCondition(…)方法,或者使用我写的一个类来做到这一点(如何使用,请参阅注释和测试类)
这里有很多答案,但一个简单的答案是创建一个完整的CompletableFuture并使用它:
CompletableFuture.completedFuture("donzo")
所以在我的测试中:
this.exactly(2).of(mockEventHubClientWrapper).sendASync(with(any(LinkedList.class)));
this.will(returnValue(new CompletableFuture<>().completedFuture("donzo")));
我只是确保所有这些东西都会被调用。如果你使用下面的代码,这个技巧是有效的:
CompletableFuture.allOf(calls.toArray(new CompletableFuture[0])).join();
它将压缩通过它,因为所有的CompletableFutures都完成了!
启动进程并使用Future等待结果。
如果你想测试逻辑,不要异步测试。
例如,测试这段代码,它对异步方法的结果起作用。
public class Example {
private Dependency dependency;
public Example(Dependency dependency) {
this.dependency = dependency;
}
public CompletableFuture<String> someAsyncMethod(){
return dependency.asyncMethod()
.handle((r,ex) -> {
if(ex != null) {
return "got exception";
} else {
return r.toString();
}
});
}
}
public class Dependency {
public CompletableFuture<Integer> asyncMethod() {
// do some async stuff
}
}
在测试中模拟使用同步实现的依赖关系。单元测试是完全同步的,运行时间为150毫秒。
public class DependencyTest {
private Example sut;
private Dependency dependency;
public void setup() {
dependency = Mockito.mock(Dependency.class);;
sut = new Example(dependency);
}
@Test public void success() throws InterruptedException, ExecutionException {
when(dependency.asyncMethod()).thenReturn(CompletableFuture.completedFuture(5));
// When
CompletableFuture<String> result = sut.someAsyncMethod();
// Then
assertThat(result.isCompletedExceptionally(), is(equalTo(false)));
String value = result.get();
assertThat(value, is(equalTo("5")));
}
@Test public void failed() throws InterruptedException, ExecutionException {
// Given
CompletableFuture<Integer> c = new CompletableFuture<Integer>();
c.completeExceptionally(new RuntimeException("failed"));
when(dependency.asyncMethod()).thenReturn(c);
// When
CompletableFuture<String> result = sut.someAsyncMethod();
// Then
assertThat(result.isCompletedExceptionally(), is(equalTo(false)));
String value = result.get();
assertThat(value, is(equalTo("got exception")));
}
}
你不测试异步行为,但你可以测试逻辑是否正确。
我更喜欢使用等待和通知。它简单明了。
@Test
public void test() throws Throwable {
final boolean[] asyncExecuted = {false};
final Throwable[] asyncThrowable= {null};
// do anything async
new Thread(new Runnable() {
@Override
public void run() {
try {
// Put your test here.
fail();
}
// lets inform the test thread that there is an error.
catch (Throwable throwable){
asyncThrowable[0] = throwable;
}
// ensure to release asyncExecuted in case of error.
finally {
synchronized (asyncExecuted){
asyncExecuted[0] = true;
asyncExecuted.notify();
}
}
}
}).start();
// Waiting for the test is complete
synchronized (asyncExecuted){
while(!asyncExecuted[0]){
asyncExecuted.wait();
}
}
// get any async error, including exceptions and assertationErrors
if(asyncThrowable[0] != null){
throw asyncThrowable[0];
}
}
基本上,我们需要创建一个最终的数组引用,在匿名内部类中使用。我宁愿创建一个布尔[],因为如果我们需要wait(),我可以设置一个值来控制。当一切都完成后,我们只需释放asyncExecuted。