How can lambdas be used to test your code?

[Teresa Sparkman]

We have a java-based test framework and use testNG. How can lambdas be used to simplify code testing?

[Campbell Ritchie]

Don't know myself, but welcome to the Ranch

[Qunfeng Wang]

There is one chapter about testing lambda expressions. If I remember it right, it's chapter 7.

[Jeanne Boyarsky]

Teresa,
Welcome to CodeRanch!

I think you are asking about how lambdas can simplify your test code. (rather than how to test lambas).

I think most tests will be too simple to benefit. But tests with more complex assertions can be simplified. For example, I often write a helper assertion method that looks like:

public void assertListContainsMatchingName(List<MyObject> list, String expectedFirst, String expectedSecond) {
  for (MyObject m : list) {
    if (expectedFirst.equals(m.getFirstName()) && expectedSecond.equals(m.getLastName()) {
      return;
    }
  }
  fail(expectedFirst + " " + expectedSecond + " not found in list);
}

Yes, I could use a comparator, but then I'd be writing it just for this method. With lambas, I could express this whole method in one line.

[Richard Warburton]

Teresa Sparkman wrote:We have a java-based test framework and use testNG. How can lambdas be used to simplify code testing?

Hi Teresa,

I think the biggest benefit isn't their direct usage in test code, although there is a good example elsewhere in this thread of that happening, its actually in making it easier to abstract over different behaviours. Being able to pass in some behaviour as a parameter makes it a lot easier to write code which is testable. In the same way that depending on any abstraction makes it easier to write code that's testable.

regards,

Richard