在对象列表上调用提取后，如何检查没有值为空？

Question

在单元测试中使用 AssertJ，我想从此类对象的列表中提取自定义对象的多个属性，extracting并检查它们是否全部非空。

例如，假设我想提取fieldA和：fieldBMyObject

import static from org.assertj.core.api.Assertions.assertThat;

List<MyObject> theList = ...; 
assertThat(theList).extracting("fieldA", "fieldB")).isNotNull();

我无法弄清楚正在检查的内容。

正在isNotNull检查：

1. 返回的iterableextracting不为空？
2. 列表中没有元组为空？
3. 每个元组中的每个值都不为空？

Answer 1

按照你的例子：

assertThat(theList).extracting("fieldA", "fieldB").isNotNull();

isNotNull只检查Iterable返回的元组extracting不为空。

flatExtracting+doesNotContainNull

要检查提取的值是否都不为空，您可以使用flatExtractingand doesNotContainNull：

assertThat(theList).flatExtracting("fieldA", "fieldB").doesNotContainNull();

如果发生故障，会产生如下消息：

java.lang.AssertionError: 
Expecting actual:
  ["value1", "value2", null, "value4"]
not to contain null elements

由于解决方案的扁平化性质，没有指示哪个对象导致了故障，但可以通过计算显示的对来识别actual。

extracting+noneMatch

可以增加复杂性以获得更清晰的错误消息：

assertThat(theList).extracting("fieldA", "fieldB").noneMatch(tuple -> tuple.toList().contains(null));

失败时会产生：

java.lang.AssertionError: [Extracted: fieldA, fieldB] 
Expecting no elements of:
  [("value1", "value2"), (null, "value4")]
to match given predicate but this element did:
  (null, "value4")

extracting+ allSatisfy+doesNotContainNull

更清晰的错误消息的另一种选择：

assertThat(theList).extracting("fieldA", "fieldB").allSatisfy(tuple -> assertThat(tuple.toList()).doesNotContainNull());

失败时会产生：

java.lang.AssertionError: [Extracted: fieldA, fieldB] 
Expecting all elements of:
  [("value1", "value2"), (null, "value4")]
to satisfy given requirements, but these elements did not:

(null, "value4")
error: 
Expecting actual:
  [null, "value4"]
not to contain null elements