Support generators 🎉

davidbanham · Nov 20, 2019 · 6defec0 · 6defec0
1 parent 9fa7814
commit 6defec0
Show file tree

Hide file tree

Showing 5 changed files with 146 additions and 50 deletions.
diff --git a/.eslintrc.js b/.eslintrc.js
@@ -10,6 +10,8 @@ module.exports = {
     strict: ['error', 'safe'],
     'no-underscore-dangle': 'off',
     'no-param-reassign': 'off',
-    'no-unused-vars': ['error', { 'argsIgnorePattern': 'next|res|req|err' }]
+    'no-unused-vars': ['error', { 'argsIgnorePattern': 'next|res|req|err' }],
+    'func-names': ['error', 'always', { generators: 'never' }],
+    'require-yield': 'off'
   }
 };
diff --git a/index.js b/index.js
@@ -1,10 +1,15 @@
 'use strict';
 
 const { IncomingMessage, ServerResponse } = require('http');
+const co = require('co');
 const Layer = require('express/lib/router/layer');
 const { Router } = require('express');
 
+// eslint-disable-next-line func-names, no-empty-function
+const GeneratorFunction = (function* () {}).constructor;
+
 const isError = (arg) => arg instanceof Error;
+const isGeneratorFunction = (arg) => arg instanceof GeneratorFunction;
 const isRequest = (arg) => arg instanceof IncomingMessage;
 const isResponse = (arg) => arg instanceof ServerResponse;
 const noop = () => {};
@@ -18,6 +23,7 @@ function copyProps(source, dest) {
 
 function wrap(fn) {
   const newFn = function newFn(...args) {
+    if (isGeneratorFunction(fn)) fn = co.wrap(fn);
     const ret = fn.apply(this, args);
     const predicates = [isError, isRequest, isResponse];
     const next = args.find((arg) => predicates.every((match) => !match(arg))) || noop;

diff --git a/package.json b/package.json
@@ -48,5 +48,8 @@
   },
   "peerDependencies": {
     "express": "^4.16.2"
+  },
+  "dependencies": {
+    "co": "^4.6.0"
   }
 }
diff --git a/test.js b/test.js
@@ -10,80 +10,160 @@ const assert = require('assert');
 const last = (arr) => arr[arr.length - 1];
 
 describe('express-async-errors', () => {
-  it('should propagate route handler errors to error handler', () => {
-    const app = express();
+  describe('supports async', () => {
+    it('should propagate route handler errors to error handler', () => {
+      const app = express();
 
-    app.get('/test', async () => {
-      throw new Error('error');
-    });
+      app.get('/test', async () => {
+        throw new Error('error');
+      });
 
-    app.use((err, req, res, next) => {
-      res.status(495).end();
+      app.use((err, req, res, next) => {
+        res.status(495).end();
+      });
+
+      return supertest(app)
+        .get('/test')
+        .expect(495);
     });
 
-    return supertest(app)
-      .get('/test')
-      .expect(495);
-  });
+    it('should propagate middleware errors to error handler', () => {
+      const app = express();
 
-  it('should propagate middleware errors to error handler', () => {
-    const app = express();
+      app.use(async () => {
+        throw new Error('error');
+      });
 
-    app.use(async () => {
-      throw new Error('error');
-    });
+      app.get('/test', async () => {
+        throw new Error('error');
+      });
 
-    app.get('/test', async () => {
-      throw new Error('error');
-    });
+      app.use((err, req, res, next) => {
+        res.status(495).end();
+      });
 
-    app.use((err, req, res, next) => {
-      res.status(495).end();
+      return supertest(app)
+        .get('/test')
+        .expect(495);
     });
 
-    return supertest(app)
-      .get('/test')
-      .expect(495);
-  });
+    it('should propagate error middleware errors to error handler', () => {
+      const app = express();
 
-  it('should propagate error middleware errors to error handler', () => {
-    const app = express();
+      app.get('/test', async () => {
+        throw new Error('error');
+      });
 
-    app.get('/test', async () => {
-      throw new Error('error');
-    });
+      app.use(async (err, req, res, next) => {
+        throw new Error('error');
+      });
 
-    app.use(async (err, req, res, next) => {
-      throw new Error('error');
-    });
+      app.use((err, req, res, next) => {
+        res.status(495).end();
+      });
 
-    app.use((err, req, res, next) => {
-      res.status(495).end();
+      return supertest(app)
+        .get('/test')
+        .expect(495);
     });
 
-    return supertest(app)
-      .get('/test')
-      .expect(495);
+    it('should propagate param middleware errors to error handler', () => {
+      const app = express();
+
+      app.param('id', async () => {
+        throw new Error('error');
+      });
+
+      app.get('/test/:id', async (err, req, next, id) => {
+        throw new Error(`error ${id}`);
+      });
+
+      app.use((err, req, res, next) => {
+        res.status(495).end();
+      });
+
+      return supertest(app)
+        .get('/test/12')
+        .expect(495);
+    });
   });
 
-  it('should propagate param middleware errors to error handler', () => {
-    const app = express();
+  describe('supports generators', () => {
+    it('should propagate route handler errors to error handler', () => {
+      const app = express();
+
+      app.get('/test', function* () {
+        throw new Error('error');
+      });
 
-    app.param('id', async () => {
-      throw new Error('error');
+      app.use((err, req, res, next) => {
+        res.status(495).end();
+      });
+
+      return supertest(app)
+        .get('/test')
+        .expect(495);
     });
 
-    app.get('/test/:id', async (err, req, next, id) => {
-      throw new Error(`error ${id}`);
+    it('should propagate middleware errors to error handler', () => {
+      const app = express();
+
+      app.use(function* () {
+        throw new Error('error');
+      });
+
+      app.get('/test', function* () {
+        throw new Error('error');
+      });
+
+      app.use((err, req, res, next) => {
+        res.status(495).end();
+      });
+
+      return supertest(app)
+        .get('/test')
+        .expect(495);
     });
 
-    app.use((err, req, res, next) => {
-      res.status(495).end();
+    it('should propagate error middleware errors to error handler', () => {
+      const app = express();
+
+      app.get('/test', function* () {
+        throw new Error('error');
+      });
+
+      app.use(async (err, req, res, next) => {
+        throw new Error('error');
+      });
+
+      app.use((err, req, res, next) => {
+        res.status(495).end();
+      });
+
+      return supertest(app)
+        .get('/test')
+        .expect(495);
     });
 
-    return supertest(app)
-      .get('/test/12')
-      .expect(495);
+    it('should propagate param middleware errors to error handler', () => {
+      const app = express();
+
+      app.param('id', function* () {
+        throw new Error('error');
+      });
+
+      app.get('/test/:id', function* (err, req, next, id) {
+        throw new Error(`error ${id}`);
+      });
+
+      app.use((err, req, res, next) => {
+        res.status(495).end();
+      });
+
+      return supertest(app)
+        .get('/test/12')
+        .expect(495);
+    });
   });
 
   it('should preserve the router stack for external routes', () => {

diff --git a/yarn.lock b/yarn.lock
@@ -345,6 +345,11 @@ cliui@^5.0.0:
     strip-ansi "^5.2.0"
     wrap-ansi "^5.1.0"
 
+co@^4.6.0:
+  version "4.6.0"
+  resolved "https://registry.yarnpkg.com/co/-/co-4.6.0.tgz#6ea6bdf3d853ae54ccb8e47bfa0bf3f9031fb184"
+  integrity sha1-bqa989hTrlTMuOR7+gvz+QMfsYQ=
+
 color-convert@^1.9.0:
   version "1.9.0"
   resolved "https://registry.yarnpkg.com/color-convert/-/color-convert-1.9.0.tgz#1accf97dd739b983bf994d56fec8f95853641b7a"