feat: Add code to errors to easily detect them

Author: danez

packages/react-docgen/src/__tests__/main-test.ts

@@ -1,5 +1,4 @@
-import { builtinHandlers, parse } from '../main.js';
-import { ERROR_MISSING_DEFINITION } from '../parse.js';
+import { builtinHandlers, parse, ERROR_CODES } from '../main.js';
 import { describe, expect, test } from 'vitest';
 
 // TODO make fixtures out of them?
@@ -189,7 +188,11 @@ describe('main', () => {
         export default NotAComponent;
       `;
 
-      expect(() => parse(source)).toThrowError(ERROR_MISSING_DEFINITION);
+      expect(() => parse(source)).toThrowError(
+        expect.objectContaining({
+          code: ERROR_CODES.MISSING_DEFINITION,
+        }),
+      );
     });
   });
 });

packages/react-docgen/src/__tests__/parse-test.ts

@@ -2,8 +2,9 @@ import type { ObjectExpression } from '@babel/types';
 import fs from 'fs';
 import { directory as tempDirectory } from 'tempy';
 import { parse as testParse, noopImporter } from '../../tests/utils';
-import parse, { ERROR_MISSING_DEFINITION } from '../parse.js';
+import parse from '../parse.js';
 import { describe, expect, test, vi } from 'vitest';
+import { ERROR_CODES } from '../error';
 
 describe('parse', () => {
   test('allows custom component definition resolvers', () => {
@@ -32,7 +33,11 @@ describe('parse', () => {
         importer: noopImporter,
         babelOptions: {},
       }),
-    ).toThrowError(ERROR_MISSING_DEFINITION);
+    ).toThrowError(
+      expect.objectContaining({
+        code: ERROR_CODES.MISSING_DEFINITION,
+      }),
+    );
     expect(resolver).toBeCalled();
 
     expect(() =>
@@ -42,7 +47,11 @@ describe('parse', () => {
         importer: noopImporter,
         babelOptions: {},
       }),
-    ).toThrowError(ERROR_MISSING_DEFINITION);
+    ).toThrowError(
+      expect.objectContaining({
+        code: ERROR_CODES.MISSING_DEFINITION,
+      }),
+    );
     expect(resolver).toBeCalled();
   });
 
@@ -99,6 +108,10 @@ describe('parse', () => {
           },
         },
       }),
-    ).toThrowError(ERROR_MISSING_DEFINITION);
+    ).toThrowError(
+      expect.objectContaining({
+        code: ERROR_CODES.MISSING_DEFINITION,
+      }),
+    );
   });
 });

packages/react-docgen/src/error.ts

@@ -0,0 +1,21 @@
+export enum ERROR_CODES {
+  MISSING_DEFINITION = 'ERR_REACTDOCGEN_MISSING_DEFINITION',
+  MULTIPLE_DEFINITIONS = 'ERR_REACTDOCGEN_MULTIPLE_DEFINITIONS',
+}
+
+const messages = new Map([
+  [ERROR_CODES.MISSING_DEFINITION, 'No suitable component definition found.'],
+  [
+    ERROR_CODES.MULTIPLE_DEFINITIONS,
+    'Multiple exported component definitions found.',
+  ],
+]);
+
+export class ReactDocgenError extends Error {
+  code: string | undefined;
+  constructor(code: ERROR_CODES) {
+    super(messages.get(code));
+
+    this.code = code;
+  }
+}

packages/react-docgen/src/main.ts

@@ -14,6 +14,7 @@ import type { Handler } from './handlers/index.js';
 import type FileState from './FileState.js';
 import type { Config } from './config.js';
 import { createConfig, defaultHandlers } from './config.js';
+import { ERROR_CODES } from './error.js';
 
 const builtinImporters = {
   fsImporter,
@@ -63,6 +64,7 @@ export {
   makeFsImporter,
   defaultParse as parse,
   utils,
+  ERROR_CODES,
 };
 
 export type { Importer, Handler, Resolver, FileState, Config, Documentation };

packages/react-docgen/src/parse.ts

@@ -7,8 +7,7 @@ import type { Handler } from './handlers/index.js';
 import type { ComponentNode } from './resolver/index.js';
 import FileState from './FileState.js';
 import type { InternalConfig } from './config.js';
-
-const ERROR_MISSING_DEFINITION = 'No suitable component definition found.';
+import { ERROR_CODES, ReactDocgenError } from './error.js';
 
 function executeHandlers(
   handlers: Handler[],
@@ -58,10 +57,8 @@ export default function parse(
   const componentDefinitions = resolver(fileState);
 
   if (componentDefinitions.length === 0) {
-    throw new Error(ERROR_MISSING_DEFINITION);
+    throw new ReactDocgenError(ERROR_CODES.MISSING_DEFINITION);
   }
 
   return executeHandlers(handlers, componentDefinitions);
 }
-
-export { ERROR_MISSING_DEFINITION };

packages/react-docgen/src/resolver/findExportedComponentDefinition.ts

@@ -14,9 +14,7 @@ import type FileState from '../FileState.js';
 import resolveComponentDefinition, {
   isComponentDefinition,
 } from '../utils/resolveComponentDefinition.js';
-
-const ERROR_MULTIPLE_DEFINITIONS =
-  'Multiple exported component definitions found.';
+import { ERROR_CODES, ReactDocgenError } from '../error.js';
 
 interface TraverseState {
   foundDefinition: NodePath<ComponentNode> | null;
@@ -48,7 +46,7 @@ function exportDeclaration(
   }
   if (definitions.length > 1 || state.foundDefinition) {
     // If a file exports multiple components, ... complain!
-    throw new Error(ERROR_MULTIPLE_DEFINITIONS);
+    throw new ReactDocgenError(ERROR_CODES.MULTIPLE_DEFINITIONS);
   }
   const definition = resolveComponentDefinition(definitions[0]);
 
@@ -84,7 +82,7 @@ const explodedVisitors = visitors.explode<TraverseState>({
       }
       if (state.foundDefinition) {
         // If a file exports multiple components, ... complain!
-        throw new Error(ERROR_MULTIPLE_DEFINITIONS);
+        throw new ReactDocgenError(ERROR_CODES.MULTIPLE_DEFINITIONS);
       }
       const definition = resolveComponentDefinition(resolvedPath);