1.什么是awaitility ？
Awaitility 是一个用于 Java 的小型领域特定语言（DSL），主要用于简化和管理异步操作的同步问题。它的主要作用包括：
-
等待异步操作完成：在测试异步代码时，Awaitility 可以帮助你等待某个条件变为真，而不需要使用复杂的线程管理或轮询机制。
-
提高测试的可读性：通过使用流畅的 API，Awaitility 使得测试代码更易于阅读和理解。
-
减少测试中的线程问题 ：避免在测试中显式地使用
Thread.sleep()，从而减少不必要的等待时间和线程问题。 -
灵活的超时和轮询间隔：允许你设置自定义的超时时间和轮询间隔，以便更好地控制等待条件的检查频率。
总之，Awaitility 使得在测试异步操作时更加简单和直观，特别是在需要等待某个条件满足的情况下。
2.代码工程
实验目的
一个使用 Awaitility 的简单示例，演示如何等待异步操作完成。假设我们有一个异步任务，该任务在后台线程中更新一个标志，我们希望在测试中等待这个标志变为
true
pom.xml
xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>Java-demo</artifactId>
<groupId>com.et</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>Awaitility</artifactId>
<properties>
<maven.compiler.source>17</maven.compiler.source>
<maven.compiler.target>17</maven.compiler.target>
</properties>
<dependencies>
<!-- Awaitility dependency -->
<dependency>
<groupId>org.awaitility</groupId>
<artifactId>awaitility</artifactId>
<version>4.2.0</version>
</dependency>
<!-- JUnit dependency for testing -->
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter</artifactId>
<version>5.8.2</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>AwaitilityExample
-
异步任务 ：
startAsyncTask方法启动一个异步任务，该任务在 5秒后将flag设置为true。 -
Awaitility 使用 ：在
main方法中，我们使用 Awaitility 的await()方法来等待flag变为true。我们设置了一个最大等待时间为 5 秒。 -
条件检查 ：
until(example::isFlag)表示我们等待example.isFlag()返回true。package com.et;
import org.awaitility.Awaitility; import java.util.concurrent.TimeUnit; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors;
public class AwaitilityExample { private volatile boolean flag = false;
scsspublic void startAsyncTask() { ExecutorService executor = Executors.newSingleThreadExecutor(); executor.submit(() -> { try { // mock async Thread.sleep(5000); flag = true; } catch (InterruptedException e) { Thread.currentThread().interrupt(); } }); executor.shutdown(); } public boolean isFlag() { return flag; } public static void main(String[] args) { AwaitilityExample example = new AwaitilityExample(); example.startAsyncTask(); // use Awaitility to wait flag for true Awaitility.await() .atMost(5, TimeUnit.SECONDS) .until(example::isFlag); System.out.println("Flag is now true!"); }}
以上只是一些关键代码，所有代码请参见下面代码仓库
代码仓库
- github.com/Harries/Jav...(awaitility )
3.测试代码
3-1.默认等待时间
await().until(Callable conditionEvaluator) 最多等待 10s 直到 conditionEvaluator 满足条件，否则 ConditionTimeoutException。
java
@Test
public void testAsynchronousNormal() {
AwaitilityExample example = new AwaitilityExample();
example.startAsyncTask();
try {
// Default timeout is 10 seconds. If the condition is not met within this period, a ConditionTimeoutException is thrown
Awaitility.await().until(new Callable<Boolean>() {
@Override
public Boolean call() throws Exception {
return example.isFlag();
}
});
} catch (Exception e) {
Assertions.fail("Run exception: " + e.getMessage() + ", error: " + e.getStackTrace()[0].toString());
}
}3-2.最多等待
await().atMost() 设置最多等待时间，如果在这时间内条件还不满足，将抛出 ConditionTimeoutException。
java
@Test
public void testAsynchronousAtMost() {
AwaitilityExample example = new AwaitilityExample();
example.startAsyncTask();
try {
// Specify a timeout of 3 seconds. If the condition is not met within this period, a ConditionTimeoutException is thrown
Awaitility.await().atMost(3, SECONDS).until(new Callable<Boolean>() {
@Override
public Boolean call() throws Exception {
return example.isFlag();
}
});
} catch (Exception e) {
Assertions.fail("Run exception: " + e.getMessage() + ", error: " + e.getStackTrace()[0].toString());
}
}3-3.至少等待
await().atLeast() 设置至少等待时间；多个条件时候用 and() 连接。
java
@Test
public void testAsynchronousAtLeast() {
AwaitilityExample example = new AwaitilityExample();
example.startAsyncTask();
try {
// Specify at least 1 second and at most 3 seconds. If the condition is not met within this period, a ConditionTimeoutException is thrown
Awaitility.await().atLeast(1, SECONDS).and().atMost(3, SECONDS).until(new Callable<Boolean>() {
@Override
public Boolean call() throws Exception {
return example.isFlag();
}
});
} catch (Exception e) {
Assertions.fail("Run exception: " + e.getMessage() + ", error: " + e.getStackTrace()[0].toString());
}
}3-4.轮询
with().pollInterval(ONE_HUNDRED_MILLISECONDS).and().with().pollDelay(50, MILLISECONDS) that is conditions are checked after 50ms then 50ms+100ms。
csharp
@Test
public void testAsynchronousPoll() {
AwaitilityExample example = new AwaitilityExample();
example.startAsyncTask();
try {
// Polling query, pollInterval specifies how often to poll, pollDelay specifies the delay between each poll
Awaitility.with().pollInterval(ONE_HUNDRED_MILLISECONDS).and().with().pollDelay(50, MILLISECONDS).await("count is greater 3").until(
new Callable<Boolean>() {
@Override
public Boolean call() throws Exception {
return example.isFlag();
}
});
} catch (Exception e) {
Assertions.fail("Run exception: " + e.getMessage() + ", error: " + e.getStackTrace()[0].toString());
}
}3-5.Fibonacci 轮询
with().pollInterval(fibonacci(SECONDS)) 非线性轮询，按照 fibonacci 数轮询。
csharp
@Test
public void testAsynchronousFibonacciPoll() {
AwaitilityExample example = new AwaitilityExample();
example.startAsyncTask();
try {
// Use Fibonacci numbers as the interval: 1, 1, 2, 3, 5, 8,..., default unit is milliseconds
Awaitility.with().pollInterval(fibonacci(SECONDS)).await("count is greater 3").until(
new Callable<Boolean>() {
@Override
public Boolean call() throws Exception {
return example.isFlag();
}
});
} catch (Exception e) {
Assertions.fail("Run exception: " + e.getMessage() + ", error: " + e.getStackTrace()[0].toString());
}
}