java - Assertj 验证集合中每个项目的字段始终为空

Question

我正在寻找一种解决方案来检查集合中的每个项目是否具有expectedNullField空字段。

以下不起作用：

assertThat(aCollection).extracting("expectedNullField").isNull();

请注意，以下内容按预期工作： assertThat(aCollection).extracting("expectedNotNullField").isNotNull();

有人帮我吗？

谢谢。

Answer 1

If you know the size (let's say it is 3) you can use

assertThat(aCollection).extracting("expectedNullField")
                       .containsOnly(null, null, null);

or if you are only interested in checking that there is a null value

assertThat(aCollection).extracting("expectedNullField")
                       .containsNull();

Note that you can't use:

    assertThat(aCollection).extracting("expectedNullField")
                           .containsOnly(null);

because it is ambiguous (containsOnly specifying a varargs params).

I might consider adding containsOnlyNullElements() in AssertJ to overcome the compiler error above.

Answer 2

您可以使用条件

Condition<YourClass> nullField = new Condition<>("expecting field to be null") {
  @Override
  public boolean matches(YourClass value) {
    return value.getField() == null;
  }
};

assertThat(aCollection).have(nullField);

这可能比其他解决方案更容易阅读

assertThat(aCollection).filteredOn("expectedNullField", not(null)).isEmpty();