jUnit: Migrates PullBasedSpliteratorTest to Kotlin

src/test/kotlin/sirius/kernel/commons/PullBasedSpliteratorTest.kt

@@ -0,0 +1,45 @@
+/*
+ * Made with all the love in the world
+ * by scireum in Remshalden, Germany
+ *
+ * Copyright by scireum GmbH
+ * http://www.scireum.de - info@scireum.de
+ */
+package sirius.kernel.commons
+
+import org.junit.jupiter.api.Assertions
+import org.junit.jupiter.api.Test
+import java.util.*
+import java.util.stream.Collectors
+import java.util.stream.Stream
+import java.util.stream.StreamSupport
+
+internal class PullBasedSpliteratorTest {
+    private class TestSpliterator : PullBasedSpliterator<Int?>() {
+        private var index = 0
+        override fun pullNextBlock(): Iterator<Int>? {
+            if (index < 10) {
+                val result: MutableList<Int> = ArrayList()
+                for (i in index until index + 5) {
+                    result.add(i)
+                }
+                index += 5
+                return result.iterator()
+            }
+            return Collections.emptyIterator()
+        }
+
+        override fun characteristics(): Int {
+            return 0
+        }
+    }
+
+    @Test
+    fun streamWorksProperly() {
+        Assertions.assertEquals(10, StreamSupport.stream(TestSpliterator(), false).count())
+        Assertions.assertEquals(
+            StreamSupport.stream(TestSpliterator(), false).collect(Collectors.toList()),
+            Stream.of(0, 1, 2, 3, 4, 5, 6, 7, 8, 9).collect(Collectors.toList())
+        )
+    }
+}