1 files changed, 33 insertions, 0 deletions
diff --git a/js/src/tests/non262/BigInt/large-bit-length.js b/js/src/tests/non262/BigInt/large-bit-length.js
new file mode 100644
index 0000000000..5f4617159b
--- /dev/null
+++ b/js/src/tests/non262/BigInt/large-bit-length.js
@@ -0,0 +1,33 @@
+// Any copyright is dedicated to the Public Domain.
+// https://creativecommons.org/licenses/publicdomain/
+
+function test(thunk, result) {
+    let val, err;
+    try {
+        val = thunk();
+    } catch (e) {
+        err = e;
+    }
+    if (err) {
+        assertEq(err instanceof RangeError, true);
+    } else {
+        assertEq(val, result);
+    }
+}
+
+const UINT32_MAX = 2**32-1;
+
+// Check that BigInt.asIntN and BigInt.asUintN either return correct results or
+// throw RangeErrors for large |bits| arguments. GMP uses a type equivalent to
+// 'unsigned long' for bit counts, which may be too small to represent all JS
+// integer indexes.
+for (let bits of [UINT32_MAX-1, UINT32_MAX, UINT32_MAX+1, Number.MAX_SAFE_INTEGER]) {
+    test(() => BigInt.asIntN(bits, 1n), 1n);
+    test(() => BigInt.asIntN(bits, 0n), 0n);
+    test(() => BigInt.asIntN(bits, -1n), -1n);
+    test(() => BigInt.asUintN(bits, 1n), 1n);
+    test(() => BigInt.asUintN(bits, 0n), 0n);
+    // Skip testing asUintN with negative BigInts since it could OOM.
+}
+
+reportCompare(true, true);