JUNIT How to check the custom object retrieved is sorted in assertthat

Question

Hi I am using Hibernate to retreive the element in sorted order FindByOrderByValueAsc.

How to check it is sorted in Junit?

Answer 1

Presumably you have the retrieved elements in a List<SomeType> .

Write a method that will iterate a List<T> using a Comparator<T> to compare successive elements, and return false if a pair is out of order.

Write the assertion to call the method on the retrieved elements with an appropriate Comparator<SomeType> . Fail the assertion if the call returns false .

Answer 2

create a Comparator for the fields that you are interested in.

Comparator<YourObject> cmp = 
Comparator.comparing(YourObject::getOrder)
          .thenComparing(YourObject::getValue);

for(int i = 0; i < yourResult.size() - 1; ++i) {
    YourObject left = yourResult.get(i);
    YourObject right = yourResult.get(i + 1);
    if(cmp.compare(left, right) > 0) {
        Assert.fail("not sorted")
    }
}

have not compiled, obviously, any of this code.

Answer 3

There are assertion libraries that can be used with JUnit that have more sophisticated assertions than JUnit itself. Eg with AssertJ you can write

assertThat(theList).containsExactly(firstValue, secondValue)