feat(rule-tester): check for parsing errors in suggestion fixes

packages/eslint-plugin/src/rules/switch-exhaustiveness-check.ts

@@ -224,18 +224,17 @@ export default createRule<Options, MessageIds>({
  requiresQuoting(missingBranchName.toString(), compilerOptions.target)
  ) {
  const escapedBranchName = missingBranchName
- .replace(/'/g, "\\'")
- .replace(/\n/g, '\\n')
- .replace(/\r/g, '\\r');
+ .replaceAll("'", "\\'")
+ .replaceAll('\n', '\\n')
+ .replaceAll('\r', '\\r');
 
  caseTest = `${symbolName}['${escapedBranchName}']`;
  }
 
- const errorMessage = `Not implemented yet: ${caseTest} case`;
- const escapedErrorMessage = errorMessage.replace(/'/g, "\\'");
-
  missingCases.push(
- `case ${caseTest}: { throw new Error('${escapedErrorMessage}') }`,
+ `case ${caseTest}: { throw new Error('Not implemented yet: ${caseTest
+ .replaceAll('\\', '\\\\')
+ .replaceAll("'", "\\'")} case') }`,
  );
  }
 
@@ -305,9 +304,7 @@ export default createRule<Options, MessageIds>({
  context.report({
  node: node.discriminant,
  messageId: 'switchIsNotExhaustive',
- data: {
- missingBranches: 'default',
- },
+ data: { missingBranches: 'default' },
  suggest: [
  {
  messageId: 'addMissingCases',

packages/eslint-plugin/tests/rules/switch-exhaustiveness-check.test.ts

@@ -1964,7 +1964,7 @@ switch (value) {
 
  switch (a) {
  case Enum.a: { throw new Error('Not implemented yet: Enum.a case') }
- case Enum['key-with\\n\\n new-line']: { throw new Error('Not implemented yet: Enum[\\'key-with\\n\\n new-line\\'] case') }
+ case Enum['key-with\\n\\n new-line']: { throw new Error('Not implemented yet: Enum[\\'key-with\\\\n\\\\n new-line\\'] case') }
  }
  `,
  },
@@ -1999,7 +1999,7 @@ switch (value) {
 
  switch (a) {
  case Enum.a: { throw new Error('Not implemented yet: Enum.a case') }
- case Enum['\\'a\\' \`b\` "c"']: { throw new Error('Not implemented yet: Enum[\\'\\\\'a\\\\' \`b\` "c"\\'] case') }
+ case Enum['\\'a\\' \`b\` "c"']: { throw new Error('Not implemented yet: Enum[\\'\\\\\\'a\\\\\\' \`b\` "c"\\'] case') }
  }
  `,
  },

packages/rule-tester/src/RuleTester.ts

@@ -254,10 +254,7 @@ export class RuleTester extends TestFramework {
  throw new Error(DUPLICATE_PARSER_ERROR_MESSAGE);
  }
  if (!test.filename) {
- return {
- ...test,
- filename: getFilename(test.parserOptions),
- };
+ return { ...test, filename: getFilename(test.parserOptions) };
  }
  return test;
  };
@@ -483,6 +480,8 @@ export class RuleTester extends TestFramework {
  output: string;
  beforeAST: TSESTree.Program;
  afterAST: TSESTree.Program;
+ config: RuleTesterConfig;
+ filename?: string;
  } {
  let config: TesterConfigWithDefaults = merge({}, this.#testerConfig);
  let code;
@@ -656,6 +655,8 @@ export class RuleTester extends TestFramework {
  // is definitely assigned within the `rule-tester/validate-ast` rule
  // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
  afterAST: cloneDeeplyExcludesParent(afterAST!),
+ config,
+ filename,
  };
  }
 
@@ -1046,6 +1047,25 @@ export class RuleTester extends TestFramework {
  [actualSuggestion],
  ).output;
 
+ // Verify if suggestion fix makes a syntax error or not.
+ const errorMessageInSuggestion = this.#linter
+ .verify(
+ codeWithAppliedSuggestion,
+ result.config,
+ result.filename,
+ )
+ .find(m => m.fatal);
+
+ assert(
+ !errorMessageInSuggestion,
+ [
+ 'A fatal parsing error occurred in suggestion fix.',
+ `Error: ${errorMessageInSuggestion?.message}`,
+ 'Suggestion output:',
+ codeWithAppliedSuggestion,
+ ].join('\n'),
+ );
+
  assert.strictEqual(
  codeWithAppliedSuggestion,
  expectedSuggestion.output,

packages/rule-tester/tests/RuleTester.test.ts

@@ -112,6 +112,7 @@ runRuleForItemSpy.mockImplementation((_1, _2, testCase) => {
  output: testCase.code,
  afterAST: EMPTY_PROGRAM,
  beforeAST: EMPTY_PROGRAM,
+ config: { parser: '' },
  };
 });
 

packages/rule-tester/tests/eslint-base/eslint-base.test.js

@@ -2045,6 +2045,48 @@ describe("RuleTester", () => {
  }, "Error should have 2 suggestions. Instead found 1 suggestions");
  });
 
+ it("should throw if suggestion fix made a syntax error.", () => {
+ assert.throw(() => {
+ ruleTester.run(
+ "foo",
+ {
+ meta: { hasSuggestions: true },
+ create(context) {
+ return {
+ Identifier(node) {
+ context.report({
+ node,
+ message: "make a syntax error",
+ suggest: [
+ {
+ desc: "make a syntax error",
+ fix(fixer) {
+ return fixer.replaceText(node, "one two");
+ }
+ }
+ ]
+ });
+ }
+ };
+ }
+ },
+ {
+ valid: [""],
+ invalid: [{
+ code: "one()",
+ errors: [{
+ message: "make a syntax error",
+ suggestions: [{
+ desc: "make a syntax error",
+ output: "one two()"
+ }]
+ }]
+ }]
+ }
+ );
+ }, /A fatal parsing error occurred in suggestion fix\.\nError: .+\nSuggestion output:\n.+/u);
+ });
+
  it("should throw if the suggestion description doesn't match", () => {
  assert.throws(() => {
  ruleTester.run("suggestions-basic", require("./fixtures/suggestions").basic, {