fix: include typechecking middleware in test mode

Author: dfreeman

ts/addon.ts

@@ -7,6 +7,7 @@ import { addon } from './lib/utilities/ember-cli-entities';
 import fork from './lib/utilities/fork';
 import TypecheckWorker from './lib/typechecking/worker';
 import TypecheckMiddleware from './lib/typechecking/middleware';
+import { Application } from 'express';
 
 export default addon({
   name: 'ember-cli-typescript',
@@ -37,9 +38,11 @@ export default addon({
   },
 
   serverMiddleware({ app }) {
-    let workerPromise = this._getTypecheckWorker();
-    let middleware = new TypecheckMiddleware(this.project, workerPromise);
-    middleware.register(app);
+    this._addTypecheckMiddleware(app);
+  },
+
+  testemMiddleware(app) {
+    this._addTypecheckMiddleware(app);
   },
 
   async postBuild() {
@@ -145,6 +148,12 @@ export default addon({
     }
   },
 
+  _addTypecheckMiddleware(app: Application) {
+    let workerPromise = this._getTypecheckWorker();
+    let middleware = new TypecheckMiddleware(this.project, workerPromise);
+    middleware.register(app);
+  },
+
   _typecheckWorker: undefined as Promise<Remote<TypecheckWorker>> | undefined,
 
   _getTypecheckWorker() {

ts/types/ember-cli/index.d.ts

@@ -36,6 +36,7 @@ declare module 'ember-cli/lib/models/addon' {
     shouldIncludeChildAddon(addon: Addon): boolean;
     isDevelopingAddon(): boolean;
     serverMiddleware(options: { app: Application }): void | Promise<void>;
+    testemMiddleware(app: Application): void;
     setupPreprocessorRegistry(type: 'self' | 'parent', registry: unknown): void;
   }
 }