Easy asynchronous asserts with JUnit & Hamcrest

Usage

These matchers are available via Maven Central. Add this to your pom.xml:

<dependency>
  <groupId>com.github.grantwest.eventually</groupId>
   <artifactId>hamcrest-eventually-matchers</artifactId>
   <version>0.0.3</version>
   <scope>test</scope>
</dependency>

Lets say another thread is supposed to add an element to a collection:

Collection<String> listOfNames; //Collection other thread is adding names to
assertThat(listOfNames, eventually(hasItem("Grant")));

To test a value we use a lambda:

boolean b = false; //Some other thread will set b to true
assertThat(() -> b, eventuallyEval(is(true)));

The eventually matchers have a default timeout of 5 seconds. The timeout can be overridden like this:

assertThat(() -> b, eventuallyEval(is(true), Duration.ofSeconds(30)));

To assert that someFunction() eventually returns true:

assertThat(() -> someFunction(), eventuallyEval(is(true)));

The matchers are known to work with:

• junit 4.12
• java-hamcrest 2.0.0.0