[JS IR] Add a test for converting arrays to String

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/BoxJsTestGenerated.java

@@ -50,6 +50,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("js/js.translator/testData/box/builtins"), Pattern.compile("^([^_](.+))\\.kt$"), null, TargetBackend.JS, true);
         }
 
+        @Test
+        @TestMetadata("arrayToString.kt")
+        public void testArrayToString() throws Exception {
+            runTest("js/js.translator/testData/box/builtins/arrayToString.kt");
+        }
+
         @Test
         @TestMetadata("hashCode.kt")
         public void testHashCode() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/IrBoxJsTestGenerated.java

@@ -50,6 +50,12 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
             KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("js/js.translator/testData/box/builtins"), Pattern.compile("^([^_](.+))\\.kt$"), null, TargetBackend.JS_IR, true);
         }
 
+        @Test
+        @TestMetadata("arrayToString.kt")
+        public void testArrayToString() throws Exception {
+            runTest("js/js.translator/testData/box/builtins/arrayToString.kt");
+        }
+
         @Test
         @TestMetadata("hashCode.kt")
         public void testHashCode() throws Exception {

js/js.translator/testData/box/builtins/arrayToString.kt

@@ -0,0 +1,81 @@
+// EXPECTED_REACHABLE_NODES: 1277
+
+// This test's purpose is not preventing regressions, but rather making sure the array-to-string conversion is tested at all.
+// The `expected` values in asserts just reflect the current state of things. It doesn't mean things _must_ be this way.
+// So feel free to update them if you're sure that the array-to-string conversion should behave differently.
+// See also: KT-14013
+
+var LOG = ""
+
+fun log(message: Any?) {
+    LOG += message
+    LOG += ";"
+}
+
+fun pullLog(): String {
+    val string = LOG
+    LOG = ""
+    return string
+}
+
+fun testKt14013() {
+    val a: Any? = arrayOf(null, 1)
+    log(a)
+    log(a.toString())
+    log(a!!.toString())
+
+    if (testUtils.isLegacyBackend()) {
+        assertEquals(",1;[...];,1;", pullLog(), "testKt14013")
+    } else {
+        assertEquals(",1;[...];[...];", pullLog(), "testKt14013")
+    }
+}
+
+fun concreteArrayToString(a: Array<Int>) {
+    log(a.toString())
+    log("$a")
+    log("" + a)
+}
+
+fun <T> genericValueToString(a: T) {
+    log(a.toString())
+    log("$a")
+    log("" + a)
+}
+
+fun anyValueToString(a: Any) {
+    log(a.toString())
+    log("$a")
+    log("" + a)
+}
+
+fun box(): String {
+    testKt14013()
+
+    val a = arrayOf(1, 2, 3)
+    concreteArrayToString(a)
+
+    if (testUtils.isLegacyBackend()) {
+        assertEquals("1,2,3;1,2,3;[...];", pullLog(), "concreteArrayToString")
+    } else {
+        assertEquals("[...];1,2,3;1,2,3;", pullLog(), "concreteArrayToString")
+    }
+
+    genericValueToString(a)
+
+    if (testUtils.isLegacyBackend()) {
+        assertEquals("[...];1,2,3;[...];", pullLog(), "genericValueToString")
+    } else {
+        assertEquals("[...];1,2,3;1,2,3;", pullLog(), "genericValueToString")
+    }
+
+    anyValueToString(a)
+
+    if (testUtils.isLegacyBackend()) {
+        assertEquals("1,2,3;1,2,3;[...];", pullLog(), "anyValueToString")
+    } else {
+        assertEquals("[...];1,2,3;1,2,3;", pullLog(), "anyValueToString")
+    }
+
+    return "OK"
+}