feat(core): initialize on preview allowlist

packages/core/index.ts

@@ -13,6 +13,7 @@ export * from './discovery';
 export * from './exceptions';
 export * from './helpers';
 export * from './injector';
+export * from './inspector';
 export * from './metadata-scanner';
 export * from './middleware';
 export * from './nest-application';

packages/core/injector/container.ts

@@ -10,6 +10,7 @@ import {
   UndefinedForwardRefException,
   UnknownModuleException,
 } from '../errors/exceptions';
+import { InitializeOnPreviewAllowlist } from '../inspector/initialize-on-preview.allowlist';
 import { SerializedGraph } from '../inspector/serialized-graph';
 import { REQUEST } from '../router/request/request-constants';
 import { ModuleCompiler } from './compiler';
@@ -80,6 +81,7 @@ export class NestContainer {
     }
     const moduleRef = new Module(type, this);
     moduleRef.token = token;
+    moduleRef.initOnPreview = this.shouldInitOnPreview(type);
     this.modules.set(token, moduleRef);
 
     const updatedScope = [].concat(scope, type);
@@ -255,4 +257,8 @@ export class NestContainer {
       isResolved: true,
     });
   }
+
+  private shouldInitOnPreview(type: Type) {
+    return InitializeOnPreviewAllowlist.has(type);
+  }
 }

packages/core/injector/injector.ts

@@ -717,7 +717,7 @@ export class Injector {
       wrapper.isLazyTransient(contextId, inquirer) ||
       wrapper.isExplicitlyRequested(contextId, inquirer);
 
-    if (this.options?.preview) {
+    if (this.options?.preview && !wrapper.host?.initOnPreview) {
       instanceHost.isResolved = true;
       return instanceHost.instance;
     }

packages/core/injector/module.ts

@@ -63,6 +63,7 @@ export class Module {
   >();
   private readonly _exports = new Set<InstanceToken>();
   private _distance = 0;
+  private _initOnPreview = false;
   private _isGlobal = false;
   private _token: string;
 
@@ -98,6 +99,14 @@ export class Module {
     this._isGlobal = global;
   }
 
+  get initOnPreview() {
+    return this._initOnPreview;
+  }
+
+  set initOnPreview(initOnPreview: boolean) {
+    this._initOnPreview = initOnPreview;
+  }
+
   get providers(): Map<InstanceToken, InstanceWrapper<Injectable>> {
     return this._providers;
   }

packages/core/inspector/index.ts

@@ -0,0 +1,2 @@
+export * from './graph-inspector';
+export * from './initialize-on-preview.allowlist';

packages/core/inspector/initialize-on-preview.allowlist.ts

@@ -0,0 +1,13 @@
+import { Type } from '@nestjs/common';
+
+export class InitializeOnPreviewAllowlist {
+  private static readonly allowlist = new WeakMap<Type, boolean>();
+
+  public static add(type: Type) {
+    this.allowlist.set(type, true);
+  }
+
+  public static has(type: Type) {
+    return this.allowlist.has(type);
+  }
+}

packages/core/nest-application-context.ts

@@ -52,7 +52,7 @@ export class NestApplicationContext<
   private readonly moduleCompiler = new ModuleCompiler();
   private shutdownCleanupRef?: (...args: unknown[]) => unknown;
   private _instanceLinksHost: InstanceLinksHost;
-  private _moduleRefsByDistance?: Array<Module>;
+  private _moduleRefsForHooksByDistance?: Array<Module>;
 
   protected get instanceLinksHost() {
     if (!this._instanceLinksHost) {
@@ -372,10 +372,7 @@ export class NestApplicationContext<
    * modules and its children.
    */
   protected async callInitHook(): Promise<void> {
-    if (this.appOptions.preview) {
-      return;
-    }
-    const modulesSortedByDistance = this.getModulesSortedByDistance();
+    const modulesSortedByDistance = this.getModulesToTriggerHooksOn();
     for (const module of modulesSortedByDistance) {
       await callModuleInitHook(module);
     }
@@ -386,10 +383,7 @@ export class NestApplicationContext<
    * modules and its children.
    */
   protected async callDestroyHook(): Promise<void> {
-    if (this.appOptions.preview) {
-      return;
-    }
-    const modulesSortedByDistance = this.getModulesSortedByDistance();
+    const modulesSortedByDistance = this.getModulesToTriggerHooksOn();
     for (const module of modulesSortedByDistance) {
       await callModuleDestroyHook(module);
     }
@@ -400,10 +394,7 @@ export class NestApplicationContext<
    * modules and its children.
    */
   protected async callBootstrapHook(): Promise<void> {
-    if (this.appOptions.preview) {
-      return;
-    }
-    const modulesSortedByDistance = this.getModulesSortedByDistance();
+    const modulesSortedByDistance = this.getModulesToTriggerHooksOn();
     for (const module of modulesSortedByDistance) {
       await callModuleBootstrapHook(module);
     }
@@ -414,10 +405,7 @@ export class NestApplicationContext<
    * modules and children.
    */
   protected async callShutdownHook(signal?: string): Promise<void> {
-    if (this.appOptions.preview) {
-      return;
-    }
-    const modulesSortedByDistance = this.getModulesSortedByDistance();
+    const modulesSortedByDistance = this.getModulesToTriggerHooksOn();
     for (const module of modulesSortedByDistance) {
       await callAppShutdownHook(module, signal);
     }
@@ -428,10 +416,7 @@ export class NestApplicationContext<
    * modules and children.
    */
   protected async callBeforeShutdownHook(signal?: string): Promise<void> {
-    if (this.appOptions.preview) {
-      return;
-    }
-    const modulesSortedByDistance = this.getModulesSortedByDistance();
+    const modulesSortedByDistance = this.getModulesToTriggerHooksOn();
     for (const module of modulesSortedByDistance) {
       await callBeforeAppShutdownHook(module, signal);
     }
@@ -445,17 +430,20 @@ export class NestApplicationContext<
     }
   }
 
-  private getModulesSortedByDistance(): Module[] {
-    if (this._moduleRefsByDistance) {
-      return this._moduleRefsByDistance;
+  private getModulesToTriggerHooksOn(): Module[] {
+    if (this._moduleRefsForHooksByDistance) {
+      return this._moduleRefsForHooksByDistance;
     }
     const modulesContainer = this.container.getModules();
     const compareFn = (a: Module, b: Module) => b.distance - a.distance;
-
-    this._moduleRefsByDistance = Array.from(modulesContainer.values()).sort(
+    const modulesSortedByDistance = Array.from(modulesContainer.values()).sort(
       compareFn,
     );
-    return this._moduleRefsByDistance;
+
+    this._moduleRefsForHooksByDistance = this.appOptions?.preview
+      ? modulesSortedByDistance.filter(moduleRef => moduleRef.initOnPreview)
+      : modulesSortedByDistance;
+    return this._moduleRefsForHooksByDistance;
   }
 
   private printInPreviewModeWarning() {

packages/testing/testing-module.builder.ts

@@ -26,7 +26,6 @@ import { TestingModule } from './testing-module';
 export class TestingModuleBuilder {
   private readonly applicationConfig = new ApplicationConfig();
   private readonly container = new NestContainer(this.applicationConfig);
-  private readonly injector = new TestingInjector();
   private readonly overloadsMap = new Map();
   private readonly module: any;
   private testingLogger: LoggerService;
@@ -70,7 +69,7 @@ export class TestingModuleBuilder {
   }
 
   public async compile(
-    options: Pick<NestApplicationContextOptions, 'snapshot'> = {},
+    options: Pick<NestApplicationContextOptions, 'snapshot' | 'preview'> = {},
   ): Promise<TestingModule> {
     this.applyLogger();
 
@@ -92,7 +91,7 @@ export class TestingModuleBuilder {
     await scanner.scan(this.module);
 
     this.applyOverloadsMap();
-    await this.createInstancesOfDependencies(graphInspector);
+    await this.createInstancesOfDependencies(graphInspector, options);
     scanner.applyApplicationProviders();
 
     const root = this.getRootModule();
@@ -137,10 +136,16 @@ export class TestingModuleBuilder {
     return modules.next().value;
   }
 
-  private async createInstancesOfDependencies(graphInspector: GraphInspector) {
+  private async createInstancesOfDependencies(
+    graphInspector: GraphInspector,
+    options: { preview?: boolean },
+  ) {
+    const injector = new TestingInjector({
+      preview: options?.preview ?? false,
+    });
     const instanceLoader = new TestingInstanceLoader(
       this.container,
-      this.injector,
+      injector,
       graphInspector,
     );
     await instanceLoader.createInstancesOfDependencies(