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

packages/rule-tester/src/RuleTester.ts

@@ -215,10 +215,7 @@ 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;
  };
@@ -444,6 +441,8 @@ 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;
@@ -617,6 +616,8 @@ 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,
  };
  }
 
@@ -981,6 +982,25 @@ 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 && errorMessageInSuggestion.message}`,
+ 'Suggestion output:',
+ codeWithAppliedSuggestion,
+ ].join('\n'),
+ );
+
  assert.strictEqual(
  codeWithAppliedSuggestion,
  expectedSuggestion.output,