handle compiler warnings in tests

Author: vpriscan

src/test/kotlin/io/reactivex/rxkotlin/BasicKotlinTests.kt

@@ -186,7 +186,7 @@ class BasicKotlinTests : KotlinTests() {
     @Test fun testTakeWhileWithIndex() {
         Observable.fromIterable(listOf(1, 2, 3))
                 .takeWhile { x -> x < 3 }
-                .zipWith(Observable.range(0, Integer.MAX_VALUE), BiFunction<Int, Int, Int> { x, i -> x })
+                .zipWith(Observable.range(0, Integer.MAX_VALUE), BiFunction<Int, Int, Int> { x, _ -> x })
                 .subscribe(received())
         verify(a, times(1)).received(1)
         verify(a, times(1)).received(2)

src/test/kotlin/io/reactivex/rxkotlin/CompletableTest.kt

@@ -39,13 +39,13 @@ class CompletableTest : KotlinTests() {
     }
 
     @Test(expected = NoSuchElementException::class) fun testCreateFromSingle() {
-        val c1 = Single.just("Hello World!").toCompletable()
+        val c1 = Single.just("Hello World!").ignoreElement()
         assertNotNull(c1)
         c1.toObservable<String>().blockingFirst()
     }
 
     @Test fun testConcatAll() {
-        var list = emptyList<Int>()
+        val list = emptyList<Int>().toMutableList()
         (0 until 10)
                 .map { v -> Completable.create { list += v } }
                 .concatAll()