Fix getRegexpRange to return correct range of the node when failed to…

… compute real range (#2857)

eslint-bridge/src/utils/utils-regex.ts

@@ -143,6 +143,10 @@ export function getRegexpLocation(
   return loc;
 }
 
+/**
+ * Returns the location of regexpNode relative to the node, which is regexp string or literal. If the computation
+ * of location fails, it returns the range of the whole node.
+ */
 export function getRegexpRange(node: estree.Node, regexpNode: regexpp.AST.Node): AST.Range {
   if (isRegexLiteral(node)) {
     return [regexpNode.start, regexpNode.end];
@@ -173,26 +177,30 @@ export function getRegexpRange(node: estree.Node, regexpNode: regexpp.AST.Node):
     const startToken = regexpNode.start - 1;
     if (tokens[startToken] === undefined) {
       // fallback when something is broken
-      return node.range!;
+      return nodeRange(node);
     }
     const start = tokens[startToken].range[0];
     // it's possible for node end to be outside of range, e.g. new RegExp('\n(|)')
     const endToken = Math.min(regexpNode.end - 2, tokens.length - 1);
     if (tokens[endToken] === undefined) {
       // fallback when something is broken
-      return node.range!;
+      return nodeRange(node);
     }
     const end = tokens[endToken].range[1];
     // +1 is needed to account for string quotes
     return [start + 1, end + 1];
   }
   if (node.type === 'TemplateLiteral') {
     // we don't support these properly
-    return node.range!;
+    return nodeRange(node);
   }
   throw new Error(`Expected regexp or string literal, got ${node.type}`);
 }
 
+function nodeRange(node: estree.Node): [number, number] {
+  return [0, node.range![1] - node.range![0]];
+}
+
 function unquote(s: string): string {
   if (s.charAt(0) !== "'" && s.charAt(0) !== '"') {
     throw new Error(`invalid string to unquote: ${s}`);

eslint-bridge/tests/utils/utils-regex.test.ts

@@ -20,8 +20,10 @@
 
 import * as esprima from 'esprima';
 import * as estree from 'estree';
-import { getRegexpRange } from 'utils';
+import { getRegexpLocation, getRegexpRange } from 'utils';
 import * as regexpp from 'regexpp';
+import { Rule, SourceCode } from 'eslint';
+import RuleContext = Rule.RuleContext;
 
 it('should get range for regexp /s*', () => {
   const program = esprima.parse(`'/s*'`);
@@ -50,3 +52,38 @@ it('should get range for \\ns', () => {
   // this fails to compute, so we return range of the whole node
   expect(range).toStrictEqual([0, 5]);
 });
+
+it('should get range for template literal', () => {
+  const program = esprima.parse('`\\ns`', { range: true });
+  const literal: estree.TemplateLiteral = program.body[0].expression;
+  const regexNode = regexpp.parseRegExpLiteral(new RegExp(literal.quasis[0].value.raw as string));
+  const quantifier = regexNode.pattern.alternatives[0].elements[1];
+  const range = getRegexpRange(literal, quantifier);
+  // this fails to compute, so we return range of the whole node
+  expect(range).toStrictEqual([0, 5]);
+});
+
+it('should throw for wrong node', () => {
+  const program = esprima.parse(`'\\ns'`, { range: true });
+  expect(() => {
+    getRegexpRange(program, undefined);
+  }).toThrow('Expected regexp or string literal, got Program');
+});
+
+it('should report correct range when fails to determine real range', () => {
+  let code = `     '\\ns'`;
+  const program = esprima.parse(code, { range: true, tokens: true, comment: true, loc: true });
+  const literal: estree.Literal = program.body[0].expression;
+  const regexNode = regexpp.parseRegExpLiteral(new RegExp(literal.value as string));
+  const quantifier = regexNode.pattern.alternatives[0].elements[1];
+  const context = {
+    getSourceCode() {
+      return new SourceCode(code, program);
+    },
+  };
+  const range = getRegexpLocation(literal, quantifier, context as RuleContext);
+  expect(range).toStrictEqual({
+    start: { column: 5, line: 1 },
+    end: { column: 10, line: 1 },
+  });
+});