LibJS: Implement RegExp.prototype.test with RegExpExec abstraction

Userland/Libraries/LibJS/Runtime/RegExpPrototype.cpp

@@ -260,9 +260,7 @@ JS_DEFINE_NATIVE_FUNCTION(RegExpPrototype::exec)
 // 22.2.5.15 RegExp.prototype.test ( S ), https://tc39.es/ecma262/#sec-regexp.prototype.test
 JS_DEFINE_NATIVE_FUNCTION(RegExpPrototype::test)
 {
-    // FIXME: This should try using dynamic properties for 'exec' first,
-    //        before falling back to builtin_exec.
-    auto regexp_object = regexp_object_from(vm, global_object);
+    auto* regexp_object = regexp_object_from(vm, global_object);
     if (!regexp_object)
         return {};
 
@@ -270,27 +268,11 @@ JS_DEFINE_NATIVE_FUNCTION(RegExpPrototype::test)
     if (vm.exception())
         return {};
 
-    // RegExps without "global" and "sticky" always start at offset 0.
-    if (!regexp_object->regex().options().has_flag_set((ECMAScriptFlags)regex::AllFlags::Internal_Stateful)) {
-        regexp_object->set(vm.names.lastIndex, Value(0), true);
-        if (vm.exception())
-            return {};
-    }
-
-    auto last_index = regexp_object->get(vm.names.lastIndex);
-    if (vm.exception())
-        return {};
-    regexp_object->regex().start_offset = last_index.to_length(global_object);
+    auto match = regexp_exec(global_object, *regexp_object, str);
     if (vm.exception())
         return {};
 
-    auto result = do_match(regexp_object->regex(), str);
-
-    regexp_object->set(vm.names.lastIndex, Value(regexp_object->regex().start_offset), true);
-    if (vm.exception())
-        return {};
-
-    return Value(result.success);
+    return Value(!match.is_null());
 }
 
 // 22.2.5.16 RegExp.prototype.toString ( ), https://tc39.es/ecma262/#sec-regexp.prototype.tostring

Userland/Libraries/LibJS/Tests/builtins/RegExp/RegExp.prototype.test.js

@@ -56,3 +56,38 @@ test("flag and options", () => {
         Function("/foo/x");
     }).toThrowWithMessage(SyntaxError, "Invalid RegExp flag 'x'");
 });
+
+test("override exec with function", () => {
+    let calls = 0;
+
+    let re = /test/;
+    let oldExec = re.exec.bind(re);
+    re.exec = function (...args) {
+        ++calls;
+        return oldExec(...args);
+    };
+
+    expect(re.test("test")).toBe(true);
+    expect(calls).toBe(1);
+});
+
+test("override exec with bad function", () => {
+    let calls = 0;
+
+    let re = /test/;
+    re.exec = function (...args) {
+        ++calls;
+        return 4;
+    };
+
+    expect(() => {
+        re.test("test");
+    }).toThrow(TypeError);
+    expect(calls).toBe(1);
+});
+
+test("override exec with non-function", () => {
+    let re = /test/;
+    re.exec = 3;
+    expect(re.test("test")).toBe(true);
+});