1 files changed, 49 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/Array/prototype/findLastIndex/array-altered-during-loop.js b/js/src/tests/test262/built-ins/Array/prototype/findLastIndex/array-altered-during-loop.js
new file mode 100644
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+++ b/js/src/tests/test262/built-ins/Array/prototype/findLastIndex/array-altered-during-loop.js
@@ -0,0 +1,49 @@
+// Copyright (C) 2021 Microsoft. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlastindex
+description: >
+  The range of elements processed is set before the first call to `predicate`.
+info: |
+  Array.prototype.findLastIndex ( predicate[ , thisArg ] )
+
+  ...
+  4. Let k be len - 1.
+  5. Repeat, while k ≥ 0,
+    ...
+    c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, 𝔽(k), O »)).
+  ...
+features: [array-find-from-last]
+---*/
+
+var arr = ['Shoes', 'Car', 'Bike'];
+var results = [];
+
+arr.findLastIndex(function(kValue) {
+  if (results.length === 0) {
+    arr.splice(1, 1);
+  }
+  results.push(kValue);
+});
+
+assert.sameValue(results.length, 3, 'predicate called three times');
+assert.sameValue(results[0], 'Bike');
+assert.sameValue(results[1], 'Bike');
+assert.sameValue(results[2], 'Shoes');
+
+results = [];
+arr = ['Skateboard', 'Barefoot'];
+arr.findLastIndex(function(kValue) {
+  if (results.length === 0) {
+    arr.push('Motorcycle');
+    arr[0] = 'Magic Carpet';
+  }
+
+  results.push(kValue);
+});
+
+assert.sameValue(results.length, 2, 'predicate called twice');
+assert.sameValue(results[0], 'Barefoot');
+assert.sameValue(results[1], 'Magic Carpet');
+
+reportCompare(0, 0);