add test for regexp matching with zero-length quantified matches

test/built-ins/RegExp/lookahead-quantifier-match-groups.js

@@ -0,0 +1,30 @@
+// Copyright (C) 2023 Kevin Gibbons. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-runtime-semantics-repeatmatcher-abstract-operation
+description: 0-length matches update the captures list if and only if they are not followed by a quantifier which allows them to match 0 times.
+info: |
+  RepeatMatcher
+    1. If max = 0, return c(x).
+    2. Let d be a new MatcherContinuation with parameters (y) that captures m, min, max, greedy, x, c, parenIndex, and parenCount and performs the following steps when called:
+      [...]
+      b. If min = 0 and y's endIndex = x's endIndex, return failure.
+      c. If min = 0, let min2 be 0; otherwise let min2 be min - 1.
+      d. If max = +∞, let max2 be +∞; otherwise let max2 be max - 1.
+      e. Return RepeatMatcher(m, min2, max2, greedy, y, c, parenIndex, parenCount).
+    3. Let cap be a copy of x's captures List.
+    4. For each integer k in the inclusive interval from parenIndex + 1 to parenIndex + parenCount, set cap[k] to undefined.
+    [...]
+    7. Let xr be the MatchState (Input, e, cap).
+    [...]
+    10. Let z be m(xr, d).
+    11. If z is not failure, return z.
+    12. Return c(x).
+includes: [compareArray.js]
+---*/
+
+assert.compareArray("abc".match(/(?:(?=(abc)))a/), ["a", "abc"], "unquantified");
+assert.compareArray("abc".match(/(?:(?=(abc)))?a/), ["a", undefined], "? quantifier");
+assert.compareArray("abc".match(/(?:(?=(abc))){1,1}a/), ["a", "abc"], "{1,1} quantifier");
+assert.compareArray("abc".match(/(?:(?=(abc))){0,1}a/), ["a", undefined], "{0,1} quantifier");