Fix: no-undef-init autofix removes comments (#12299)

Author: mdjermanovic

lib/rules/no-undef-init.js

@@ -37,7 +37,8 @@ module.exports = {
  init = node.init && node.init.name,
  scope = context.getScope(),
  undefinedVar = astUtils.getVariableByName(scope, "undefined"),
- shadowed = undefinedVar && undefinedVar.defs.length > 0;
+ shadowed = undefinedVar && undefinedVar.defs.length > 0,
+ lastToken = sourceCode.getLastToken(node);
 
  if (init === "undefined" && node.parent.kind !== "const" && !shadowed) {
  context.report({
@@ -54,6 +55,11 @@ module.exports = {
  // Don't fix destructuring assignment to `undefined`.
  return null;
  }
+
+ if (sourceCode.commentsExistBetween(node.id, lastToken)) {
+ return null;
+ }
+
  return fixer.removeRange([node.id.range[1], node.range[1]]);
  }
  });

tests/lib/rules/no-undef-init.js

@@ -92,6 +92,62 @@ ruleTester.run("no-undef-init", rule, {
  output: "for(var i in [1,2,3]){let a; for(var j in [1,2,3]){}}",
  parserOptions: { ecmaVersion: 6 },
  errors: [{ message: "It's not necessary to initialize 'a' to undefined.", type: "VariableDeclarator" }]
+ },
+
+ // Should not autofix if it would remove comments
+ {
+ code: "let /* comment */a = undefined;",
+ output: "let /* comment */a;",
+ parserOptions: { ecmaVersion: 6 },
+ errors: [{ message: "It's not necessary to initialize 'a' to undefined.", type: "VariableDeclarator" }]
+ },
+ {
+ code: "let a/**/ = undefined;",
+ output: null,
+ parserOptions: { ecmaVersion: 6 },
+ errors: [{ message: "It's not necessary to initialize 'a' to undefined.", type: "VariableDeclarator" }]
+ },
+ {
+ code: "let a /**/ = undefined;",
+ output: null,
+ parserOptions: { ecmaVersion: 6 },
+ errors: [{ message: "It's not necessary to initialize 'a' to undefined.", type: "VariableDeclarator" }]
+ },
+ {
+ code: "let a//\n= undefined;",
+ output: null,
+ parserOptions: { ecmaVersion: 6 },
+ errors: [{ message: "It's not necessary to initialize 'a' to undefined.", type: "VariableDeclarator" }]
+ },
+ {
+ code: "let a = /**/undefined;",
+ output: null,
+ parserOptions: { ecmaVersion: 6 },
+ errors: [{ message: "It's not necessary to initialize 'a' to undefined.", type: "VariableDeclarator" }]
+ },
+ {
+ code: "let a = //\nundefined;",
+ output: null,
+ parserOptions: { ecmaVersion: 6 },
+ errors: [{ message: "It's not necessary to initialize 'a' to undefined.", type: "VariableDeclarator" }]
+ },
+ {
+ code: "let a = undefined/* comment */;",
+ output: "let a/* comment */;",
+ parserOptions: { ecmaVersion: 6 },
+ errors: [{ message: "It's not necessary to initialize 'a' to undefined.", type: "VariableDeclarator" }]
+ },
+ {
+ code: "let a = undefined/* comment */, b;",
+ output: "let a/* comment */, b;",
+ parserOptions: { ecmaVersion: 6 },
+ errors: [{ message: "It's not necessary to initialize 'a' to undefined.", type: "VariableDeclarator" }]
+ },
+ {
+ code: "let a = undefined//comment\n, b;",
+ output: "let a//comment\n, b;",
+ parserOptions: { ecmaVersion: 6 },
+ errors: [{ message: "It's not necessary to initialize 'a' to undefined.", type: "VariableDeclarator" }]
  }
  ]
 });