Test-Driven Java Development, Second Edition - Second Edition

AssertJ

AssertJ works in a similar way to Hamcrest. A major difference is that AssertJ assertions can be concatenated.

To work with AssertJ, the dependency must be added to Gradle's dependencies:

testCompile 'org.assertj:assertj-core:2.0.0' 

Let's compare JUnit asserts with AssertJ:

Assert.assertEquals(5, friendships.getFriendsList("Joe").size()); 
List<String> friendsOfJoe =    Arrays.asList("Audrey", "Peter", "Michael", "Britney", "Paul");Assert.assertTrue(  friendships.getFriendsList("Joe")   .containsAll (friendsOfJoe) 
); 

The same two asserts can be concatenated to a single one in AssertJ:

assertThat(friendships.getFriendsList("Joe")) 
  .hasSize(5) 
  .containsOnly("Audrey", "Peter", "Michael", "Britney", "Paul");

This was a nice improvement. There ...