1 files changed, 60 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/TypedArray/prototype/findLastIndex/BigInt/predicate-call-changes-value.js b/js/src/tests/test262/built-ins/TypedArray/prototype/findLastIndex/BigInt/predicate-call-changes-value.js
new file mode 100644
index 0000000000..a2e1ee53d2
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+++ b/js/src/tests/test262/built-ins/TypedArray/prototype/findLastIndex/BigInt/predicate-call-changes-value.js
@@ -0,0 +1,60 @@
+// Copyright (C) 2021 Microsoft. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.findlastindex
+description: >
+  Change values during predicate call
+info: |
+  %TypedArray%.prototype.findLastIndex ( predicate [ , thisArg ] )
+
+  ...
+  6. Repeat, while k ≥ 0
+    ...
+    c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, 𝔽(k), O »)).
+  ...
+includes: [compareArray.js, testBigIntTypedArray.js]
+features: [BigInt, TypedArray, array-find-from-last]
+---*/
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  var arr = [10n, 20n, 30n];
+  var sample;
+  var result;
+
+  sample = new TA(3);
+  sample.findLastIndex(function(val, i) {
+    sample[i] = arr[i];
+
+    assert.sameValue(val, 0n, "value is not mapped to instance");
+  });
+  assert(compareArray(sample, arr), "values set during each predicate call");
+
+  sample = new TA(arr);
+  result = sample.findLastIndex(function(val, i) {
+    if ( i === 2 ) {
+      sample[0] = 7n;
+    }
+    return val === 7n;
+  });
+  assert.sameValue(result, 0, "value found");
+
+  sample = new TA(arr);
+  result = sample.findLastIndex(function(val, i) {
+    if ( i === 2 ) {
+      sample[0] = 7n;
+    }
+    return val === 10n;
+  });
+  assert.sameValue(result, -1, "value not found");
+
+  sample = new TA(arr);
+  result = sample.findLastIndex(function(val, i) {
+    if ( i < 2 ) {
+      sample[2] = 7n;
+    }
+    return val === 7n;
+  });
+  assert.sameValue(result, -1, "value not found - changed after call");
+});
+
+reportCompare(0, 0);