Allow post-fastboot middlewares to recover from fastboot failure

Author: Arjan Singh

src/index.js

@@ -53,23 +53,16 @@ function fastbootExpressMiddleware(distPath, options) {
         })
         .catch(error => {
           log(500, error.stack);
+          res.status(500);
           next(error);
-          res.sendStatus(500);
         });
     }
 
     function failure(error) {
-      if (error.name === "UnrecognizedURLError") {
-        next();
-      } else {
-        next(error);
-        log(500, "Unknown Error: " + error.stack);
-        if (error.stack) {
-          res.status(500).send(error.stack);
-        } else {
-          res.sendStatus(500);
-        }
+      if (error.name !== "UnrecognizedURLError") {
+        res.status(500);
       }
+      next(error);
     }
   };
 }

test/helpers/test-http-server.js

@@ -24,7 +24,15 @@ class TestHTTPServer {
     if (options.errorHandling) {
       app.use((err, req, res, next) => {
         res.set('x-test-error', 'error handler called');
-        next();
+        next(err);
+      });
+    }
+
+    if (options.recoverErrors) {
+      app.use((err, req, res, next) => {
+        res.set('x-test-recovery', 'recovered response');
+        res.status(200);
+        res.send('hello world');
       });
     }
 

test/middleware-test.js

@@ -65,68 +65,6 @@ describe("FastBoot", function() {
       });
   });
 
-  it("renders no FastBoot markup if the resilient flag is set", function() {
-    let middleware = fastbootMiddleware({
-      distPath: fixture('rejected-promise'),
-      resilient: true
-    });
-    server = new TestHTTPServer(middleware);
-
-    return server.start()
-      .then(() => server.request('/'))
-      .then(html => {
-        expect(html).to.not.match(/error/);
-      });
-  });
-
-  it("propagates to error handling middleware if the resilient flag is set", function() {
-    let middleware = fastbootMiddleware({
-      distPath: fixture('rejected-promise'),
-      resilient: true
-    });
-    server = new TestHTTPServer(middleware, { errorHandling: true });
-
-    return server.start()
-      .then(() => server.request('/', { resolveWithFullResponse: true }))
-      .then(({ body, statusCode, headers }) => {
-        expect(statusCode).to.equal(200);
-        expect(headers['x-test-error']).to.match(/error handler called/);
-        expect(body).to.match(/hello world/);
-      });
-  });
-
-  it("propagates to error handling middleware if the resilient flag is not set", function() {
-    let middleware = fastbootMiddleware({
-      distPath: fixture('rejected-promise'),
-      resilient: false,
-    });
-    server = new TestHTTPServer(middleware, { errorHandling: true });
-
-    return server.start()
-      .then(() => server.request('/', { resolveWithFullResponse: true }))
-      .catch(({ statusCode, response: { headers } }) => {
-        expect(statusCode).to.equal(500);
-        expect(headers['x-test-error']).to.match(/error handler called/);
-      });
-  });
-
-  it("is does not propagate errors when the reslient flag is set and there is no error handling middleware", function() {
-    let middleware = fastbootMiddleware({
-      distPath: fixture('rejected-promise'),
-      resilient: true,
-    });
-    server = new TestHTTPServer(middleware, { errorHandling: false });
-
-    return server.start()
-      .then(() => server.request('/', { resolveWithFullResponse: true }))
-      .then(({ body, statusCode, headers }) => {
-        expect(statusCode).to.equal(200);
-        expect(headers['x-test-error']).to.not.match(/error handler called/);
-        expect(body).to.not.match(/error/);
-        expect(body).to.match(/hello world/);
-      });
-  });
-
   it("can be provided with a custom FastBoot instance", function() {
     let fastboot = new FastBoot({
       distPath: fixture('basic-app')
@@ -181,4 +119,103 @@ describe("FastBoot", function() {
         });
     }
   });
+
+  describe('when reslient mode is enabled', function () {
+    it("renders no FastBoot markup", function() {
+      let middleware = fastbootMiddleware({
+        distPath: fixture('rejected-promise'),
+        resilient: true
+      });
+      server = new TestHTTPServer(middleware);
+
+      return server.start()
+        .then(() => server.request('/'))
+        .then(html => {
+          expect(html).to.not.match(/error/);
+        });
+    });
+
+    it("propagates to error handling middleware", function() {
+      let middleware = fastbootMiddleware({
+        distPath: fixture('rejected-promise'),
+        resilient: true
+      });
+      server = new TestHTTPServer(middleware, { errorHandling: true });
+
+      return server.start()
+        .then(() => server.request('/', { resolveWithFullResponse: true }))
+        .then(({ body, statusCode, headers }) => {
+          expect(statusCode).to.equal(200);
+          expect(headers['x-test-error']).to.match(/error handler called/);
+          expect(body).to.match(/hello world/);
+        });
+    });
+
+    it("is does not propagate errors when and there is no error handling middleware", function() {
+      let middleware = fastbootMiddleware({
+        distPath: fixture('rejected-promise'),
+        resilient: true,
+      });
+      server = new TestHTTPServer(middleware, { errorHandling: false });
+
+      return server.start()
+        .then(() => server.request('/', { resolveWithFullResponse: true }))
+        .then(({ body, statusCode, headers }) => {
+          expect(statusCode).to.equal(200);
+          expect(headers['x-test-error']).to.not.match(/error handler called/);
+          expect(body).to.not.match(/error/);
+          expect(body).to.match(/hello world/);
+        });
+    });
+
+    it("allows post-fastboot middleware to recover the response when it fails", function() {
+      let middleware = fastbootMiddleware({
+        distPath: fixture('rejected-promise'),
+        resilient: true
+      });
+      server = new TestHTTPServer(middleware, { recoverErrors: true });
+
+      return server.start()
+        .then(() => server.request('/', { resolveWithFullResponse: true }))
+        .then(({ body, statusCode, headers }) => {
+          expect(statusCode).to.equal(200);
+          expect(headers['x-test-recovery']).to.match(/recovered response/);
+          expect(body).to.match(/hello world/);
+        });
+    });
+  });
+
+  describe('when reslient mode is disabled', function () {
+    it("propagates to error handling middleware", function() {
+      let middleware = fastbootMiddleware({
+        distPath: fixture('rejected-promise'),
+        resilient: false,
+      });
+      server = new TestHTTPServer(middleware, { errorHandling: true });
+
+      return server.start()
+        .then(() => server.request('/', { resolveWithFullResponse: true }))
+        .catch(({ statusCode, response: { headers } }) => {
+          expect(statusCode).to.equal(500);
+          expect(headers['x-test-error']).to.match(/error handler called/);
+        });
+    });
+
+    it("allows post-fastboot middleware to recover the response when it fails", function() {
+      let middleware = fastbootMiddleware({
+        distPath: fixture('rejected-promise'),
+        resilient: false
+      });
+      server = new TestHTTPServer(middleware, { recoverErrors: true });
+
+      return server.start()
+        .then(() => server.request('/', { resolveWithFullResponse: true }))
+        .then(({ body, statusCode, headers }) => {
+          expect(statusCode).to.equal(200);
+          expect(headers['x-test-recovery']).to.match(/recovered response/);
+          expect(body).to.match(/hello world/);
+        });
+    });
+  });
+
 });