Hi, is there a way to say "listA should contain on...

# kotest

[Klitos Kyriacou]

Hi, is there a way to say "listA should contain only the elements a, b, c"? For example:

listOf(1, 1, 1).shouldContainOnly(1) -- passes (if there was such a function as shouldContainOnly)
listOf(1, 1, 2, 2).shouldContainOnly(1, 2) -- passes
listOf(1, 1, 2).shouldContainOnly(1) -- fails

[Emil Kantis]

shouldContainExactly

[Emil Kantis]

although your 2nd example would fail, only listOf(1, 1, 2, 2).shouldContainExactly(1, 1, 2, 2) would pass.

[Klitos Kyriacou]

The 1st example would fail too.

[Emil Kantis]

listOf(1,1,2,2).forAll {
            it.shouldBeOneOf(1, 2)
         }

[Klitos Kyriacou]

Thanks, Emil. I was looking for a succinctly named, single function equivalent to AssertJ's containsOnly function, but this will do.

[Emil Kantis]

If you'd like you could create an issue for it, I think it's likely to get accepted 🙂

[Klitos Kyriacou]

Thanks, Issue 3213 created.

[Davio]

We have shouldContainExactlyInAnyOrder right?

[Klitos Kyriacou]

listOf(1, 1, 1).shouldContainExactlyInAnyOrder(1) fails.

[Klitos Kyriacou]

In the absence of shouldContainOnly Kotest can be used only with workarounds, such as by making changes to the actual value to be tested. Compare AssertJ's containsOnly with attempts to use Kotest:

package org.example

import io.kotest.assertions.throwables.shouldThrow
import io.kotest.matchers.collections.*
import org.junit.jupiter.api.Test
import org.assertj.core.api.Assertions.*

class KotlinPracticeTest {
    @Test
    fun foo() {
        // AssertJ's containsOnly method is what is required
        assertThat(listOf(1, 1, 1)).containsOnly(1)
        assertThat(listOf(1, 1, 2, 2)).containsOnly(1, 2)
        shouldThrow<AssertionError> { assertThat(listOf(1, 1, 2)).containsOnly(1, 2, 3) }

        // There is no Kotest method to do the same thing:
        // it only works with workarounds such as converting the actual value to be tested
        listOf(1, 1, 1).toSet().shouldContainExactlyInAnyOrder(1)
        listOf(1, 1, 2, 2).toSet().shouldContainExactlyInAnyOrder(1, 2)  //fails
        shouldThrow<AssertionError> { listOf(1, 1, 2).toSet().shouldContainExactlyInAnyOrder(1) }
    }
}

[Davio]

Ah yes, in that case we could use a generic shouldMatchAll kind of function that you can use with a predicate