fix(regex): support unicode regex flags(#3642)

This PR adds support for unicode regexes. I.e.: `/\u{0}/gu` isn't mutated to `/\u/gu` (which is invalid).

* update dependency weapon-regex to v1 to support unicode regexes, see stryker-mutator/weapon-regex#165
* pass regex flags argument to weapon-regex.

Closes #3579

Co-authored-by: Hugo van Rijswijk <git@hugovr.nl>

packages/instrumenter/package.json

@@ -41,7 +41,7 @@
     "@stryker-mutator/api": "6.1.2",
     "@stryker-mutator/util": "6.1.2",
     "angular-html-parser": "~1.8.0",
-    "weapon-regex": "~0.6.0"
+    "weapon-regex": "~1.0.2"
   },
   "devDependencies": {
     "@babel/preset-react": "7.18.6",

packages/instrumenter/src/mutators/regex-mutator.ts

@@ -1,5 +1,5 @@
 import babel, { NodePath, type types as t } from '@babel/core';
-import weaponRegex from 'weapon-regex';
+import * as weaponRegex from 'weapon-regex';
 
 import { NodeMutator } from './index.js';
 
@@ -19,29 +19,38 @@ function isObviousRegexString(path: NodePath<t.StringLiteral>) {
     path.parentPath.node.arguments[0] === path.node
   );
 }
-const weaponRegexOptions: weaponRegex.Options = { mutationLevels: [1] };
+
+function getFlags(path: NodePath<t.NewExpression>): string | undefined {
+  if (types.isStringLiteral(path.node.arguments[1])) {
+    return path.node.arguments[1].value;
+  }
+  return undefined;
+}
+
+const weaponRegexOptions: weaponRegex.MutationOptions = { mutationLevels: [1] };
 
 export const regexMutator: NodeMutator = {
   name: 'Regex',
 
   *mutate(path) {
     if (path.isRegExpLiteral()) {
-      for (const replacementPattern of mutatePattern(path.node.pattern)) {
+      for (const replacementPattern of mutatePattern(path.node.pattern, path.node.flags)) {
         const replacement = types.regExpLiteral(replacementPattern, path.node.flags);
         yield replacement;
       }
     } else if (path.isStringLiteral() && isObviousRegexString(path)) {
-      for (const replacementPattern of mutatePattern(path.node.value)) {
+      const flags = getFlags(path.parentPath as NodePath<t.NewExpression>);
+      for (const replacementPattern of mutatePattern(path.node.value, flags)) {
         yield types.stringLiteral(replacementPattern);
       }
     }
   },
 };
 
-function mutatePattern(pattern: string): string[] {
+function mutatePattern(pattern: string, flags: string | undefined): string[] {
   if (pattern.length) {
     try {
-      return weaponRegex.mutate(pattern, weaponRegexOptions).map((mutant) => mutant.pattern);
+      return weaponRegex.mutate(pattern, flags, weaponRegexOptions).map((mutant) => mutant.pattern);
     } catch (err: any) {
       console.error(
         `[RegexMutator]: The Regex parser of weapon-regex couldn't parse this regex pattern: "${pattern}". Please report this issue at https://github.com/stryker-mutator/weapon-regex/issues. Inner error: ${err.message}`

packages/instrumenter/test/unit/mutators/regex-mutator.spec.ts

@@ -1,6 +1,5 @@
 import { expect } from 'chai';
 import sinon from 'sinon';
-import weaponRegex from 'weapon-regex';
 
 import { regexMutator as sut } from '../../../src/mutators/regex-mutator.js';
 import { expectJSMutation } from '../../helpers/expect-mutation.js';
@@ -20,16 +19,14 @@ describe(sut.name, () => {
 
   it("should not crash if a regex couldn't be parsed", () => {
     // Arrange
-    const weaponRegexStub = sinon.stub(weaponRegex, 'mutate');
-    weaponRegexStub.throws(new Error('[Error] Parser: Position 1:1, found "[[]]"'));
     const errorStub = sinon.stub(console, 'error');
 
     // Act
-    expectJSMutation(sut, '/[[]]/');
+    expectJSMutation(sut, 'new RegExp("*(a|$]")');
 
     // Assert
     expect(errorStub).calledWith(
-      '[RegexMutator]: The Regex parser of weapon-regex couldn\'t parse this regex pattern: "[[]]". Please report this issue at https://github.com/stryker-mutator/weapon-regex/issues. Inner error: [Error] Parser: Position 1:1, found "[[]]"'
+      '[RegexMutator]: The Regex parser of weapon-regex couldn\'t parse this regex pattern: "*(a|$]". Please report this issue at https://github.com/stryker-mutator/weapon-regex/issues. Inner error: [Error] Parser: Position 1:1, found "*(a|$]"'
     );
   });
 
@@ -40,4 +37,20 @@ describe(sut.name, () => {
   it('should not mutate the flags of a new RegExp constructor', () => {
     expectJSMutation(sut, 'new RegExp("", "\\\\d{4}")');
   });
+
+  it('should not pass flags if no flags are defined', () => {
+    expectJSMutation(sut, '/\\u{20}/', '/\\u/');
+  });
+
+  it('should pass flags in regex literals', () => {
+    expectJSMutation(sut, '/\\u{20}/u');
+  });
+
+  it('should pass flags in new RegExp constructors', () => {
+    expectJSMutation(sut, 'new RegExp("\\\\u{20}", "u")');
+  });
+
+  it('should only pass flags in new RegExp constructors if it is a string literal', () => {
+    expectJSMutation(sut, 'new RegExp("\\\\u{20}", foo)', 'new RegExp("\\\\u", foo)');
+  });
 });