Add functional replacement test

test/built-ins/RegExp/prototype/Symbol.replace/named-groups-fn.js

@@ -0,0 +1,59 @@
+// Copyright (C) 2020 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-regexp.prototype-@@replace
+description: >
+  "groups" value is passed as last argument of replacer unless it is undefined.
+info: |
+  RegExp.prototype [ @@replace ] ( string, replaceValue )
+
+  [...]
+  14. For each result in results, do
+    [...]
+    j. Let namedCaptures be ? Get(result, "groups").
+    k. If functionalReplace is true, then
+      [...]
+      iv. If namedCaptures is not undefined, then
+        1. Append namedCaptures as the last element of replacerArgs.
+      v. Let replValue be ? Call(replaceValue, undefined, replacerArgs).
+features: [Symbol.replace, regexp-named-groups]
+---*/
+
+var matchGroups;
+var re = /./;
+re.exec = function() {
+  return {
+    length: 1,
+    0: "a",
+    index: 0,
+    groups: matchGroups,
+  };
+};
+
+var replacerCalls = 0;
+var replacerLastArg;
+var replacer = function() {
+  replacerCalls++;
+  replacerLastArg = arguments[arguments.length - 1];
+};
+
+matchGroups = null;
+re[Symbol.replace]("a", replacer);
+assert.sameValue(replacerCalls, 1);
+assert.sameValue(replacerLastArg, matchGroups);
+
+matchGroups = undefined;
+re[Symbol.replace]("a", replacer);
+assert.sameValue(replacerCalls, 2);
+assert.sameValue(replacerLastArg, "a");
+
+matchGroups = 10;
+re[Symbol.replace]("a", replacer);
+assert.sameValue(replacerCalls, 3);
+assert.sameValue(replacerLastArg, matchGroups);
+
+matchGroups = {};
+re[Symbol.replace]("a", replacer);
+assert.sameValue(replacerCalls, 4);
+assert.sameValue(replacerLastArg, matchGroups);