[refactor] Common function for Ember-App instance destruction

src/ember-app.js

@@ -176,6 +176,24 @@ class EmberApp {
     });
   }
 
+  destroyAppInstance(result, timeout) {
+    const instance = result.instance;
+
+    if (!timeout) return () => instance.destroy();
+
+    // start a timer to destroy the appInstance forcefully in the given ms.
+    // This is a failure mechanism so that node process doesn't get wedged if the `visit` never completes.
+    const destructionTimer = setTimeout(function() {
+      instance.destroy();
+      result.error = new Error(`App instance was forcefully destroyed in ${timeout}ms`);
+    }, timeout);
+
+    return function() {
+      clearTimeout(destructionTimer);
+      instance.destroy();
+    };
+  }
+
   /**
    * Creates a new application instance and renders the instance at a specific
    * URL, returning a promise that resolves to a {@link Result}. The `Result`
@@ -203,7 +221,7 @@ class EmberApp {
     let res = options.response;
     let html = options.html || this.html;
     let disableShoebox = options.disableShoebox || false;
-    let destroyAppInstanceInMs = options.destroyAppInstanceInMs;
+    let destroyAppInstanceInMs = parseInt(options.destroyAppInstanceInMs, 10);
 
     let shouldRender = (options.shouldRender !== undefined) ? options.shouldRender : true;
     let bootOptions = buildBootOptions(shouldRender);
@@ -215,38 +233,26 @@ class EmberApp {
 
     let doc = bootOptions.document;
 
-    let instance;
-
     let result = new Result({
       doc: doc,
       html: html,
       fastbootInfo: fastbootInfo
     });
 
-    let destroyAppInstanceTimer;
-    if (parseInt(destroyAppInstanceInMs, 10) > 0) {
-      // start a timer to destroy the appInstance forcefully in the given ms.
-      // This is a failure mechanism so that node process doesn't get wedged if the `visit` never completes.
-      destroyAppInstanceTimer = setTimeout(function() {
-        if (instance && !result.instanceDestroyed) {
-          result.instanceDestroyed = true;
-          result.error = new Error('App instance was forcefully destroyed in ' + destroyAppInstanceInMs + 'ms');
-          instance.destroy();
-        }
-      }, destroyAppInstanceInMs);
-    }
 
     return this.buildAppInstance()
       .then(appInstance => {
-        instance = appInstance;
+        const instance = appInstance;
+
         result.instance = instance;
+        result.destroyInstance = this.destroyAppInstance(result, destroyAppInstanceInMs);
         registerFastBootInfo(fastbootInfo, instance);
 
         return instance.boot(bootOptions);
       })
       .then(() => result.instanceBooted = true)
-      .then(() => instance.visit(path, bootOptions))
-      .then(() => waitForApp(instance))
+      .then(() => result.instance.visit(path, bootOptions))
+      .then(() => waitForApp(result.instance))
       .then(() => {
         if (!disableShoebox) {
           // if shoebox is not disabled, then create the shoebox and send API data
@@ -255,16 +261,7 @@ class EmberApp {
       })
       .catch(error => result.error = error)
       .then(() => result._finalize())
-      .finally(() => {
-        if (instance && !result.instanceDestroyed) {
-          result.instanceDestroyed = true;
-          instance.destroy();
-
-          if (destroyAppInstanceTimer) {
-            clearTimeout(destroyAppInstanceTimer);
-          }
-        }
-      });
+      .finally(() => result.destroyInstance());
   }
 
   /**