typescript-eslint · JoshuaKGoldberg · Jan 7, 2024 · Dec 27, 2023 · Dec 28, 2023 · Dec 28, 2023
diff --git a/packages/utils/src/eslint-utils/getParserServices.ts b/packages/utils/src/eslint-utils/getParserServices.ts
@@ -3,10 +3,14 @@ import type {
   ParserServices,
   ParserServicesWithTypeInformation,
 } from '../ts-estree';
+import { parserPathSeemsToBeTSESLint } from './parserPathSeemsToBeTSESLint';
 
-const ERROR_MESSAGE =
+const ERROR_MESSAGE_REQUIRES_PARSER_SERVICES =
   'You have used a rule which requires parserServices to be generated. You must therefore provide a value for the "parserOptions.project" property for @typescript-eslint/parser.';
 
+const ERROR_MESSAGE_UNKNOWN_PARSER =
+  'Note: detected a parser other than @typescript-eslint/parser. Make sure the parser is configured to forward "parserOptions.project" to @typescript-eslint/parser.';
+
 /* eslint-disable @typescript-eslint/unified-signatures */
 /**
  * Try to retrieve type-aware parser service from context.
@@ -72,7 +76,7 @@ function getParserServices(
     // eslint-disable-next-line deprecation/deprecation, @typescript-eslint/no-unnecessary-condition -- TODO - support for ESLint v9 with backwards-compatible support for ESLint v8
     context.parserServices.tsNodeToESTreeNodeMap == null
   ) {
-    throw new Error(ERROR_MESSAGE);
+    throwError(context.parserPath);
   }
 
   // if a rule requires full type information, then hard fail if it doesn't exist
@@ -82,12 +86,23 @@ function getParserServices(
     context.parserServices.program == null &&
     !allowWithoutFullTypeInformation
   ) {
-    throw new Error(ERROR_MESSAGE);
+    throwError(context.parserPath);
   }
 
   // eslint-disable-next-line deprecation/deprecation -- TODO - support for ESLint v9 with backwards-compatible support for ESLint v8
   return context.parserServices;
 }
 /* eslint-enable @typescript-eslint/unified-signatures */
 
+function throwError(parserPath: string): never {
+  throw new Error(
+    parserPathSeemsToBeTSESLint(parserPath)
+      ? ERROR_MESSAGE_REQUIRES_PARSER_SERVICES
+      : [
+          ERROR_MESSAGE_REQUIRES_PARSER_SERVICES,
+          ERROR_MESSAGE_UNKNOWN_PARSER,
+        ].join('\n'),
+  );
+}
+
 export { getParserServices };
diff --git a/packages/utils/src/eslint-utils/parserPathSeemsToBeTSESLint.ts b/packages/utils/src/eslint-utils/parserPathSeemsToBeTSESLint.ts
@@ -0,0 +1,3 @@
+export function parserPathSeemsToBeTSESLint(parserPath: string): boolean {
+  return /(?:typescript-eslint|\.\.)[\w/\\]*parser/.test(parserPath);
+}
diff --git a/packages/utils/tests/eslint-utils/getParserServices.test.ts b/packages/utils/tests/eslint-utils/getParserServices.test.ts
@@ -0,0 +1,107 @@
+/* eslint-disable @typescript-eslint/no-explicit-any, deprecation/deprecation -- wild and wacky testing */
+import type * as ts from 'typescript';
+
+import type { ParserServices, TSESLint, TSESTree } from '../../src';
+import { ESLintUtils } from '../../src';
+
+type UnknownRuleContext = Readonly<TSESLint.RuleContext<string, unknown[]>>;
+
+const defaults = {
+  parserPath: '@typescript-eslint/parser/dist/index.js',
+  parserServices: {
+    esTreeNodeToTSNodeMap: new Map<TSESTree.Node, ts.Node>(),
+    program: {},
+    tsNodeToESTreeNodeMap: new Map<ts.Node, TSESTree.Node>(),
+  } as unknown as ParserServices,
+};
+
+const createMockRuleContext = (
+  overrides: Partial<UnknownRuleContext> = {},
+): UnknownRuleContext =>
+  ({
+    ...defaults,
+    ...overrides,
+  }) as unknown as UnknownRuleContext;
+
+describe('getParserServices', () => {
+  it('throws a standard error when parserOptions.esTreeNodeToTSNodeMap is missing and the parser is known', () => {
+    const context = createMockRuleContext({
+      parserServices: {
+        ...defaults.parserServices,
+        esTreeNodeToTSNodeMap: undefined as any,
+      },
+    });
+
+    expect(() => ESLintUtils.getParserServices(context)).toThrow(
+      new Error(
+        'You have used a rule which requires parserServices to be generated. You must therefore provide a value for the "parserOptions.project" property for @typescript-eslint/parser.',
+      ),
+    );
+  });
+
+  it('throws an augment error when parserOptions.esTreeNodeToTSNodeMap is missing and the parser is unknown', () => {
+    const context = createMockRuleContext({
+      parserPath: '@babel/parser.js',
+      parserServices: {
+        ...defaults.parserServices,
+        esTreeNodeToTSNodeMap: undefined as any,
+      },
+    });
+
+    expect(() => ESLintUtils.getParserServices(context)).toThrow(
+      new Error(
+        'You have used a rule which requires parserServices to be generated. You must therefore provide a value for the "parserOptions.project" property for @typescript-eslint/parser.\n' +
+          'Note: detected a parser other than @typescript-eslint/parser. Make sure the parser is configured to forward "parserOptions.project" to @typescript-eslint/parser.',
+      ),
+    );
+  });
+
+  it('throws an error when parserOptions.tsNodeToESTreeNodeMap is missing', () => {
+    const context = createMockRuleContext({
+      parserServices: {
+        ...defaults.parserServices,
+        tsNodeToESTreeNodeMap: undefined as any,
+      },
+    });
+
+    expect(() => ESLintUtils.getParserServices(context)).toThrow(
+      new Error(
+        'You have used a rule which requires parserServices to be generated. You must therefore provide a value for the "parserOptions.project" property for @typescript-eslint/parser.',
+      ),
+    );
+  });
+
+  it('throws an error when parserServices.program is missing and allowWithoutFullTypeInformation is false', () => {
+    const context = createMockRuleContext({
+      parserServices: {
+        ...defaults.parserServices,
+        program: undefined as any,
+      },
+    });
+
+    expect(() => ESLintUtils.getParserServices(context)).toThrow(
+      new Error(
+        'You have used a rule which requires parserServices to be generated. You must therefore provide a value for the "parserOptions.project" property for @typescript-eslint/parser.',
+      ),
+    );
+  });
+
+  it('returns when parserServices.program is missing and allowWithoutFullTypeInformation is true', () => {
+    const context = createMockRuleContext({
+      parserServices: {
+        ...defaults.parserServices,
+        program: undefined as any,
+      },
+    });
+
+    expect(ESLintUtils.getParserServices(context, true)).toBe(
+      context.parserServices,
+    );
+  });
+
+  it('returns when parserServices is filled out', () => {
+    const context = createMockRuleContext();
+
+    expect(ESLintUtils.getParserServices(context)).toBe(context.parserServices);
+  });
+});
diff --git a/packages/utils/tests/eslint-utils/parserPathSeemsToBeTSESLint.test.ts b/packages/utils/tests/eslint-utils/parserPathSeemsToBeTSESLint.test.ts
@@ -0,0 +1,24 @@
+import { parserPathSeemsToBeTSESLint } from '../../src/eslint-utils/parserPathSeemsToBeTSESLint';
+
+describe('parserPathSeemsToBeTSESLint', () => {
+  test.each([
+    ['local.js', false],
+    ['../other.js', false],
+    ['@babel/eslint-parser/lib/index.cjs', false],
+    ['@babel\\eslint-parser\\lib\\index.cjs', false],
+    ['node_modules/@babel/eslint-parser/lib/index.cjs', false],
+    ['../parser/dist/index.js', true],
+    ['../@typescript-eslint/parser/dist/index.js', true],
+    ['@typescript-eslint/parser/dist/index.js', true],
+    ['@typescript-eslint\\parser\\dist\\index.js', true],
+    ['node_modules/@typescript-eslint/parser/dist/index.js', true],
+    ['/path/to/typescript-eslint/parser/dist/index.js', true],
+    ['/path/to/typescript-eslint/parser/index.js', true],
+    ['/path/to/typescript-eslint/packages/parser/dist/index.js', true],
+    ['/path/to/typescript-eslint/packages/parser/index.js', true],
+    ['/path/to/@typescript-eslint/packages/parser/dist/index.js', true],
+    ['/path/to/@typescript-eslint/packages/parser/index.js', true],
+  ])('%s', (parserPath, expected) => {
+    expect(parserPathSeemsToBeTSESLint(parserPath)).toBe(expected);
+  });
+});