Anybody have any good examples of using the String...

# kotlintest

[Quinn]

Anybody have any good examples of using the StringSpec with listeners? First dip into kotlin in a while and I'm trying to start with unit testing.

[Matteo Mirk]

you’re lucky: it was discussed just above 😉 https://kotlinlang.slack.com/archives/C18FWPKKL/p1575815899174100

[LeoColman]

class MyTest : StringSpec() {
    override fun listeners() = listOf(myListener)

   init {
      "My First Test" {
      }
      "My Second Test" {
      }
   }
}

[Quinn]

I ran into the same problem as he did with not being able to instantiate a variable before the tests were run. I was trying to convert this over to the kotlin test StringSpec syntax.

abstract class BaseCacheTest {
	protected lateinit var cache: Cache

	@Before
	fun setup() {
		for (i in 0..99) {
			cache[i] = i
		}
	}

	@After
	fun tearDown() = cache.clear()

	@Test
	fun shouldClearAllEntries() {
		Assert.assertTrue(cache.size > 0)

		cache.clear()

		Assert.assertTrue(cache.size == 0)
	}

	@Test
	open fun shouldRemoveEntry() {
		Assert.assertNotNull(cache[1])

		cache.remove(1)

		Assert.assertNull(cache[1])
	}

[LeoColman]

You're inheriting BaseCacheTest in your tests?

[Quinn]

No I didn't try that. I was trying to write using the StringSpec in lambda form and the programming style is different enough from OOP junit that I was struggling. I'll give that a try when I get home.

[LeoColman]

No, I mean, your test is an abstract class

[LeoColman]

Your JUnit test

[LeoColman]

You want to convert that to exactly one test?

[Quinn]

No, sorry for the lousy explanation. This code comes from this study, https://github.com/kezhenxu94/cache-lite implemented in kotlin on caching. I was actually trying to physically rewrite the code base to gain an understanding of caching and kotlin.

[LeoColman]

Ok, so for your exact scenario, you probably want something like this:

class CacheTest : StringSpec() {

private lateinit var cache: Cache

override fun beforeTest(testCase: TestCase) {
    for(i in 0..99)
        cache[i] = i
}

override fun afterTest(testCase: TestCase, result: TestResult) {
    cache.clear()
}

init {
    "Should clear all entries" {
        cache.size shouldBeGreaterThan 0
        cache.clear()
        cache.size shouldBe 0
    }

    "Should remove entry" {
        cache[1] shouldNotBe null
        cache.remove(1)
        cache[1] shouldBe null
    }
}

}

[LeoColman]

That would be the exact transition to StringSpec

[Quinn]

I see. I was trying to inherit from both StringSpec and TestListener and that was becoming very complicated. This is much simpler.

[LeoColman]

StringSpec is a TestListener

[Quinn]

Ahhhh

[LeoColman]

With a TestListener you can do some more advanced stuff, for example sharing listeners between tests

[LeoColman]

Think of a TestListener as a powerful JUnit Rule

[Quinn]

Ok, that makes sense, I was creating a second listener object and trying to register that in my string spec like in the documentation. https://github.com/kotlintest/kotlintest/blob/master/doc/reference.md#listeners

This was leading to my cache not being initialized.

Thanks for your help, I'm going to continue working on rewriting this tonight.

[Quinn]

It's actually mentioned right there in the documentation. I missed that completely

[Quinn]

It's also important to notice that every Spec is also a TestListener, therefore you may override these functions directly in Spec.

[LeoColman]

xD

[LeoColman]

Take a look at the default listeners and extensions:
https://github.com/kotlintest/kotlintest/blob/master/doc/extensions.md

[LeoColman]

You can see some use cases for when to use listeners there

[Quinn]

Thanks, I've got some work to do. I'm hoping to do many of the build-your-own-x examples in kotlin. I want to start with a strong testing mental structure.