how to use assertj extracting map property

Question

I am using AssertJ. I have a class like MyObj. And I have a List of MyObj.

Class MyObj {
    ...
    Map<K,V> myMap;
    ...
}

When I use:

1. assertThat(list).extracting("myMap"), I cannot use .containsKey() method.
2. I also tried using assertThat(list).extracting("myMap", Map.class), but it does not work either.

What is the right way of using it?

Solution 1

AssertJ has entry() method. You can assert map value like this.

assertThat(list)
    .extracting("myMap")
    .contains(entry("foo1", "bar1"), entry("foo2", "bar2"));

Here's javadoc : http://joel-costigliola.github.io/assertj/core/api/org/assertj/core/data/MapEntry.html

Solution 2

The simplest way to assert the contents of your map is chaining the extracting method:

    MyObj o1 = new MyObj();
    o1.getMyMap().put("foo", "Hello");
    o1.getMyMap().put("bar", "Bye");
    MyObj o2 = new MyObj();
    o2.getMyMap().put("foo", "Hola");
    o2.getMyMap().put("bar", "Adios");

    List<MyObj> myObjs = Arrays.asList(o1, o2);
    assertThat(myObjs).extracting("myMap").extracting("foo").contains("Hello", "Hola");
    assertThat(myObjs).extracting("myMap").extracting("bar").contains("Bye", "Adios");

Solution 3

Extracting feature is documented here: http://joel-costigliola.github.io/assertj/assertj-core-features-highlight.html#extracted-properties-assertion

You have executable examples in assertj-examples, and specifically in IterableAssertionsExamples.

Hope it helps !

Solution 4

If you want to use the containsKey method, you must know the type of the key at compile time (that is, you can't rely on generics). Supposing myMap is a Map<String, Long> you could do:

assertThat(list)
  .extracting("myMap")
  .asInstanceOf(InstanceOfAssertFactories.map(String.class, Long.class))
  .containsKey("key");

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