Fix FP S6594 (sonar-prefer-regexp-exec): Ignore match count use case (

#4540)

Co-authored-by: Ilia Kebets <[email protected]>

its/ruling/src/test/expected/jsts/desktop/typescript-S6594.json

@@ -1,7 +1,4 @@
 {
-"desktop:app/src/crash/crash-app.tsx": [
-65
-],
 "desktop:app/src/lib/actions-log-parser/action-log-parser.ts": [
 140,
 219,
@@ -30,35 +27,19 @@
 200,
 226
 ],
-"desktop:app/src/lib/markdown-filters/emoji-filter.ts": [
-64
-],
 "desktop:app/src/lib/markdown-filters/issue-link-filter.ts": [
 112
 ],
 "desktop:app/src/lib/parse-pac-string.ts": [
 72
 ],
-"desktop:app/src/lib/progress/lfs.ts": [
-54
-],
-"desktop:app/src/lib/remove-remote-prefix.ts": [
-10
-],
 "desktop:app/src/models/app-menu.ts": [
 161
 ],
-"desktop:app/src/models/branch.ts": [
-73,
-87
-],
 "desktop:app/src/models/commit-identity.ts": [
 23
 ],
 "desktop:app/src/models/git-author.ts": [
 3
-],
-"desktop:script/changelog/parser.ts": [
-20
 ]
 }

its/ruling/src/test/expected/jsts/reddit-mobile/javascript-S6594.json

@@ -1,6 +1,5 @@
 {
 "reddit-mobile:assets/js/trackingEvents.es6.js": [
-62,
 67
 ]
 }

packages/jsts/src/rules/S6594/cb.fixture.js

@@ -6,3 +6,14 @@ foo.match(/foo/);
 // ^^^^^
 // fix@qf1 {{Replace with "RegExp.exec()"}}
 // edit@qf1 [[ec=19]] {{RegExp(/bar/).exec('foo');}}
+
+const m1 = 'foo'.match(/bar/); // Compliant: we're checking `m1.length` below
+if (m1.length > 0) {
+ console.log(m1[0]);
+}
+
+let m2;
+m2 = 'foo'.match(/bar/); // Compliant: we're checking `m2?.length` below
+if (m2?.length > 0) {
+ console.log(m2[0]);
+}

packages/jsts/src/rules/S6594/rule.ts

@@ -21,7 +21,13 @@
 
 import { Rule } from 'eslint';
 import * as estree from 'estree';
-import { isRequiredParserServices, isString } from '../helpers';
+import {
+ getNodeParent,
+ getVariableFromName,
+ isMemberWithProperty,
+ isRequiredParserServices,
+ isString,
+} from '../helpers';
 import { getParsedRegex } from '../helpers/regex';
 
 export const rule: Rule.RuleModule = {
@@ -44,11 +50,22 @@ export const rule: Rule.RuleModule = {
  if (!isString(object, services)) {
  return;
  }
+
  const callExpr = (memberExpr as any).parent as estree.CallExpression;
  const regex = getParsedRegex(callExpr.arguments[0], context);
  if (regex?.flags.global) {
  return;
  }
+
+ const variable = getLhsVariable(callExpr);
+ for (const ref of variable?.references ?? []) {
+ const id = ref.identifier;
+ const parent = getNodeParent(id);
+ if (isMemberWithProperty(parent, 'length')) {
+ return;
+ }
+ }
+
  context.report({
  node: property,
  messageId: 'useExec',
@@ -66,5 +83,23 @@ export const rule: Rule.RuleModule = {
  });
  },
  };
+
+ /**
+ * Extracts the left-hand side variable of expressions
+ * like `x` in `const x = <node>` or `x` in `x = <node>`.
+ */
+ function getLhsVariable(node: estree.Node) {
+ const parent = getNodeParent(node);
+ let ident: estree.Identifier | undefined;
+ if (parent.type === 'VariableDeclarator' && parent.id.type === 'Identifier') {
+ ident = parent.id;
+ } else if (parent.type === 'AssignmentExpression' && parent.left.type === 'Identifier') {
+ ident = parent.left;
+ }
+ if (ident) {
+ return getVariableFromName(context, ident.name);
+ }
+ return null;
+ }
  },
 };