SafeMergeArrayTest.kt

@TestInstance(TestInstance.Lifecycle.PER_METHOD)
@DisplayName("Given we merge two streams")
class SafeMergeArrayTest {

    @Nested
    @DisplayName("When the first stream throws an error")
    inner class FirstStreamError {

        private val completable1 = Completable.error(
            Throwable("error 1")
        ).subscribeOn(Schedulers.io())

        @Nested
        @DisplayName("When the second stream succeeds")
        inner class SecondStreamSuccess {

            private val completable2 = Completable.complete()
                .subscribeOn(Schedulers.io())

            @Test
            fun `then the merged stream throws an error`() {
                safeMergeArray(completable1, completable2).test().await().assertError {
                    it.message == "error 1"
                }
            }
        }

        @Nested
        @DisplayName("When the second stream throws an error")
        inner class SecondStreamError {

            private val completable2 = Completable.error(
                Throwable("error 2")
            ).subscribeOn(Schedulers.io())

            @Test
            fun `then the merged stream throws an error`() {
                safeMergeArray(completable1, completable2).test().await().assertError {
                    it.message == "error 1"
                }
            }
        }
    }

    @Nested
    @DisplayName("When the first stream succeeds")
    inner class FirstStreamSuccess {

        private val completable1 = Completable.complete()
            .subscribeOn(Schedulers.io())

        @Nested
        @DisplayName("When the second stream succeeds")
        inner class SecondStreamSuccess {

            private val completable2 = Completable.complete()
                .subscribeOn(Schedulers.io())

            @Test
            fun `then the merged stream succeeds`() {
                safeMergeArray(completable1, completable2).test().await().assertComplete()
            }
        }

        @Nested
        @DisplayName("When the second stream throws an error")
        inner class SecondStreamError {

            private val completable2 = Completable.error(
                Throwable("error 2")
            ).subscribeOn(Schedulers.io())

            @Test
            fun `then the merged stream throws an error`() {
                safeMergeArray(completable1, completable2).test().await().assertError {
                    it.message == "error 2"
                }
            }
        }
    }
}