#KT-1391 Fixed

libraries/stdlib/test/iterators/IteratorsTest.kt

@@ -1,7 +1,8 @@
 package iterators
 
 import kotlin.test.assertEquals
-import org.junit.Test
+import org.junit.Test as test
+import kotlin.test.failsWith
 
 class IteratorsTest {
 
@@ -11,24 +12,24 @@ class IteratorsTest {
         return iterate<Int> { when (index++) { 0 -> a; 1 -> b; else -> { val result = a + b; a = b; b = result; result } } }
     }
 
-    Test fun filterAndTakeWhileExtractTheElementsWithinRange() {
+    test fun filterAndTakeWhileExtractTheElementsWithinRange() {
         assertEquals(arrayList(144, 233, 377, 610, 987), fibonacci().filter { it > 100 }.takeWhile { it < 1000 }.toList())
     }
 
-    Test fun foldReducesTheFirstNElements() {
+    test fun foldReducesTheFirstNElements() {
         val sum = { (a: Int, b: Int) -> a + b }
         assertEquals(arrayList(13, 21, 34, 55, 89).fold(0, sum), fibonacci().filter { it > 10 }.take(5).fold(0, sum))
     }
 
-    Test fun takeExtractsTheFirstNElements() {
+    test fun takeExtractsTheFirstNElements() {
         assertEquals(arrayList(0, 1, 1, 2, 3, 5, 8, 13, 21, 34), fibonacci().take(10).toList())
     }
 
-    Test fun mapAndTakeWhileExtractTheTransformedElements() {
+    test fun mapAndTakeWhileExtractTheTransformedElements() {
         assertEquals(arrayList(0, 3, 3, 6, 9, 15), fibonacci().map { it * 3 }.takeWhile { (i: Int) -> i < 20 }.toList())
     }
 
-    Test fun flatMapAndTakeExtractTheTransformedElements() {
+    test fun flatMapAndTakeExtractTheTransformedElements() {
         fun intToBinaryDigits() = { (i: Int) ->
             val binary = Integer.toBinaryString(i).sure()
             var index = 0
@@ -47,11 +48,24 @@ class IteratorsTest {
         assertEquals(expected, fibonacci().flatMap<Int, Char>(intToBinaryDigits()).take(10).toList())
     }
 
-    Test fun joinConcatenatesTheFirstNElementsAboveAThreshold() {
+    test fun joinConcatenatesTheFirstNElementsAboveAThreshold() {
         assertEquals("13, 21, 34, 55, 89, ...", fibonacci().filter { it > 10 }.makeString(separator = ", ", limit = 5))
     }
 
-    Test fun toStringJoinsNoMoreThanTheFirstTenElements() {
+    test fun requireNoNulls() {
+        val iter = arrayList<String?>("foo", "bar").iterator()
+        val notNull = iter.requireNoNulls()
+        assertEquals(arrayList("foo", "bar"), notNull.toList())
+
+        val iterWithNulls = arrayList("foo", null, "bar").iterator()
+        val notNull2 = iterWithNulls.requireNoNulls()
+        failsWith<IllegalArgumentException> {
+            // should throw an exception as we have a null
+            notNull2.toList()
+        }
+    }
+
+    test fun toStringJoinsNoMoreThanTheFirstTenElements() {
         assertEquals("0, 1, 1, 2, 3, 5, 8, 13, 21, 34, ...", fibonacci().makeString(limit = 10))
         assertEquals("13, 21, 34, 55, 89, 144, 233, 377, 610, 987, ...", fibonacci().filter {  it > 10 }.makeString(limit = 10))
         assertEquals("144, 233, 377, 610, 987", fibonacci().filter { it > 100 }.takeWhile { it < 1000 }.makeString())