Hamcrest or assertj : test element in list with requirements

Question

using hamcrest and java 8, what's the easiest way (one liner) to assert that a collection contains a element with a specific set of requirements? I'd like to be able to retrieve the element, if it exists, and perform some tests on it, in one go (and in a readable form). Or maybe at least assert that a list contains a specific element, and return it in one go, so that I can then perform some tests on it.

Answer 1

With AssertJ I would try one of these:

• anySatisfy (takes a Consumer to express the requirements ending with informative errors)
• anyMatch (takes a Predicate, error is less informative)
• hasOnlyOneElementSatisfying (takes a Consumer, work iif exactly one element matches)
• haveAtLeastOne (takes a Condition which is a like an Hamcrest macther)

To get a one liner, it is likely that you will have to extract the Condition, Consumer or Predicate to a variable/field instead of inlining it.

Follow the javadoc links, they all have code examples showing how to they can be used. You can also have a look at the assertj-examples project, a showcase of AssertJ.

Hope that helps