feat: @feathersjs/express allow to pass an existing Express application instance

packages/express/lib/index.js

@@ -7,9 +7,9 @@ const authentication = require('./authentication');
 const notFound = require('./not-found-handler');
 const rest = require('./rest');
 
-function feathersExpress (feathersApp) {
+function feathersExpress (feathersApp, expressApp = express()) {
   if (!feathersApp) {
-    return express();
+    return expressApp;
   }
 
   if (typeof feathersApp.setup !== 'function') {
@@ -20,7 +20,6 @@ function feathersExpress (feathersApp) {
     throw new Error(`@feathersjs/express requires an instance of a Feathers application version 3.x or later (got ${feathersApp.version || 'unknown'})`);
   }
 
-  const expressApp = express();
   // An Uberproto mixin that provides the extended functionality
   const mixin = {
     use (location) {

packages/express/test/index.test.js

@@ -29,6 +29,13 @@ describe('@feathersjs/express', () => {
     assert.strictEqual(typeof app, 'function');
   });
 
+  it('allows to use an existing Express instance', () => {
+    const expressApp = express();
+    const app = expressify(feathers(), expressApp);
+
+    assert.strictEqual(app, expressApp);
+  });
+
   it('exports `express.rest`', () => {
     assert.ok(typeof expressify.rest === 'function');
   });