Fix NullPointerException in treapListOf(1).subString(1, 1) (and many …

…other cases) (#16)
Certora · May 23, 2024 · 1bb0beb · 1bb0beb
1 parent 840d5eb
commit 1bb0beb
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Showing 2 changed files with 27 additions and 2 deletions.
diff --git a/collect/src/main/kotlin/com/certora/collect/TreapListNode.kt b/collect/src/main/kotlin/com/certora/collect/TreapListNode.kt
@@ -267,8 +267,8 @@ internal class TreapListNode<E> private constructor(
     private fun split(index: Int): Pair<TreapListNode<E>?, TreapListNode<E>?> = stepToIndex(
         index,
         found = { left to this.with(left = null) },
-        goLeft = { left!!.split(it).let { it.first to this.with(left = it.second) }},
-        goRight = { right!!.split(it).let { this.with(right = it.first) to it.second }},
+        goLeft = { left?.split(it).let { it?.first to this.with(left = it?.second) }},
+        goRight = { right?.split(it).let { this.with(right = it?.first) to it?.second }},
     )
 
     private fun removeNode(element: E): TreapListNode<E>? {

diff --git a/collect/src/test/kotlin/com/certora/collect/TreapListTest.kt b/collect/src/test/kotlin/com/certora/collect/TreapListTest.kt
@@ -403,4 +403,29 @@ class TreapListTest {
         val large = (1..100000).toTreapList()
         large.removeAt(large.size / 2)
     }
+
+    @Test
+    fun subList() {
+        assertEquals(listOf<Int>(), treapListOf<Int>().subList(0, 0))
+        assertFailsWith<IndexOutOfBoundsException> { treapListOf<Int>().subList(0, 1) }
+        assertFailsWith<IndexOutOfBoundsException> { treapListOf<Int>().subList(1, 1) }
+
+        assertEquals(listOf<Int>(), treapListOf(1).subList(0, 0))
+        assertEquals(listOf<Int>(), treapListOf(1).subList(1, 1))
+        assertEquals(listOf(1), treapListOf(1).subList(0, 1))
+        assertFailsWith<IndexOutOfBoundsException> { treapListOf<Int>().subList(1, 2) }
+        assertFailsWith<IndexOutOfBoundsException> { treapListOf<Int>().subList(2, 2) }
+
+        assertEquals(listOf<Int>(), treapListOf(1, 2).subList(2, 2))
+        assertEquals(listOf(1), treapListOf(1, 2).subList(0, 1))
+        assertEquals(listOf(2), treapListOf(1, 2).subList(1, 2))
+        assertEquals(listOf(1, 2), treapListOf(1, 2).subList(0, 2))
+
+        assertEquals(listOf(1), treapListOf(1, 2, 3).subList(0, 1))
+        assertEquals(listOf(1, 2), treapListOf(1, 2, 3).subList(0, 2))
+        assertEquals(listOf(2, 3), treapListOf(1, 2, 3).subList(1, 3))
+        assertEquals(listOf(3), treapListOf(1, 2, 3).subList(2, 3))
+        assertEquals(listOf<Int>(), treapListOf(1, 2, 3).subList(3, 3))
+        assertEquals(listOf(1, 2, 3), treapListOf(1, 2, 3).subList(0, 3))
+    }
 }