Add string replacement test

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

@@ -0,0 +1,44 @@
+// Copyright (C) 2020 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-getsubstitution
+description: >
+  RegExp.prototype[Symbol.replace] works with named capture references as expected.
+  (string replacement)
+info: |
+  GetSubstitution ( matched, str, position, captures, namedCaptures, replacement )
+
+  Table: Replacement Text Symbol Substitutions
+
+  Unicode Characters: $<
+  Replacement text:
+    1. If namedCaptures is undefined, the replacement text is the literal string $<.
+    2. Else,
+      a. Assert: Type(namedCaptures) is Object.
+      b. Scan until the next > U+003E (GREATER-THAN SIGN).
+      c. If none is found, the replacement text is the String "$<".
+      d. Else,
+        i. Let groupName be the enclosed substring.
+        ii. Let capture be ? Get(namedCaptures, groupName).
+        iii. If capture is undefined, replace the text through > with the empty String.
+        iv. Otherwise, replace the text through > with ? ToString(capture).
+features: [Symbol.replace, regexp-named-groups]
+---*/
+
+assert.sameValue(/b/u[Symbol.replace]("abc", "$&$<food"), "ab$<foodc");
+assert.sameValue(/./g[Symbol.replace]("ab", "c$<foo>d"), "c$<foo>dc$<foo>d");
+assert.sameValue(/(b)./[Symbol.replace]("abc", "$<foo>$1"), "a$<foo>b");
+
+assert.sameValue(/(?<foo>.)(?<bar>.)/[Symbol.replace]("abc", "$<bar>$<foo>"), "bac");
+assert.sameValue(/(?<foo>.)(?<bar>.)/gu[Symbol.replace]("abc", "$2$<foo>$1"), "baac");
+assert.sameValue(/(?<foo>b)/u[Symbol.replace]("abc", "c$<bar>d"), "acdc");
+assert.sameValue(/(?<foo>.)/g[Symbol.replace]("abc", "$<$1>"), "");
+assert.sameValue(/(?<foo>b)/[Symbol.replace]("abc", "$<>"), "ac");
+assert.sameValue(/(?<foo>.)(?<bar>.)/g[Symbol.replace]("abc", "$2$1"), "bac");
+assert.sameValue(/(?<foo>b)/u[Symbol.replace]("abc", "$<foo"), "a$<fooc");
+assert.sameValue(/(?<foo>.)/gu[Symbol.replace]("abc", "$<bar>"), "");
+assert.sameValue(/(?<foo>b)/[Symbol.replace]("abc", "$$<foo>$&"), "a$<foo>bc");
+
+assert.sameValue(/(?<𝒜>b)/u[Symbol.replace]("abc", "d$<𝒜>$`"), "adbac");
+assert.sameValue(/(?<$𐒤>b)/gu[Symbol.replace]("abc", "$'$<$𐒤>d"), "acbdc");