Ember.Application and Ember.EngineInstance.boot are public (#27504)

types/ember/index.d.ts

@@ -480,6 +480,11 @@ declare module 'ember' {
             **/
             Router: Router;
             registry: Registry;
+            /**
+             *  Initialize the application and return a promise that resolves with the `Application`
+             *  object when the boot process is complete.
+             */
+            boot(): Promise<Application>;
         }
         /**
         The `ApplicationInstance` encapsulates all of the stateful aspects of a
@@ -1111,6 +1116,12 @@ declare module 'ember' {
              * Unregister a factory.
              */
             unregister(fullName: string): any;
+
+            /**
+             *  Initialize the `EngineInstance` and return a promise that resolves
+             *  with the instance itself when the boot process is complete.
+             */
+            boot(): Promise<EngineInstance>;
         }
         /**
          * This mixin defines the common interface implemented by enumerable objects

types/ember/test/application-instance.ts

@@ -18,3 +18,9 @@ appInstance.register('some:injection', class Foo {}, {
 
 appInstance.factoryFor('router:main');
 appInstance.lookup('route:basic');
+
+appInstance.boot();
+
+(async function() {
+  await appInstance.boot();
+}());

types/ember/test/engine-instance.ts

@@ -0,0 +1,26 @@
+import EngineInstance from '@ember/engine/instance';
+
+const engineInstance = EngineInstance.create();
+engineInstance.register('some:injection', class Foo {});
+
+engineInstance.register('some:injection', class Foo {}, {
+  singleton: true,
+});
+
+engineInstance.register('some:injection', class Foo {}, {
+  instantiate: false,
+});
+
+engineInstance.register('some:injection', class Foo {}, {
+    singleton: false,
+    instantiate: true,
+});
+
+engineInstance.factoryFor('router:main');
+engineInstance.lookup('route:basic');
+
+engineInstance.boot();
+
+(async function() {
+  await engineInstance.boot();
+}());

types/ember/tsconfig.json

@@ -23,6 +23,7 @@
         "test/lib/assert.ts",
         "test/application.ts",
         "test/application-instance.ts",
+        "test/engine-instance.ts",
         "test/ember-tests.ts",
         "test/error.ts",
         "test/event.ts",