refactor: introduce noop inspector

packages/common/interfaces/nest-application-context-options.interface.ts

@@ -37,4 +37,11 @@ export class NestApplicationContextOptions {
    * @default false
    */
   preview?: boolean;
+
+  /**
+   * Whether to generate a serialized graph snapshot.
+   *
+   * @default false
+   */
+  snapshot?: boolean;
 }

packages/core/inspector/noop-graph-inspector.ts

@@ -0,0 +1,5 @@
+import { GraphInspector } from './graph-inspector';
+
+export const NoopGraphInspector: GraphInspector = Object.create(
+  GraphInspector.prototype,
+);

packages/core/nest-factory.ts

@@ -20,6 +20,7 @@ import { NestContainer } from './injector/container';
 import { Injector } from './injector/injector';
 import { InstanceLoader } from './injector/instance-loader';
 import { GraphInspector } from './inspector/graph-inspector';
+import { NoopGraphInspector } from './inspector/noop-graph-inspector';
 import { MetadataScanner } from './metadata-scanner';
 import { NestApplication } from './nest-application';
 import { NestApplicationContext } from './nest-application-context';
@@ -75,7 +76,7 @@ export class NestFactoryStatic {
 
     const applicationConfig = new ApplicationConfig();
     const container = new NestContainer(applicationConfig);
-    const graphInspector = new GraphInspector(container);
+    const graphInspector = this.createGraphInspector(appOptions, container);
 
     this.setAbortOnError(serverOrOptions, options);
     this.registerLoggerConfiguration(appOptions);
@@ -120,7 +121,7 @@ export class NestFactoryStatic {
     );
     const applicationConfig = new ApplicationConfig();
     const container = new NestContainer(applicationConfig);
-    const graphInspector = new GraphInspector(container);
+    const graphInspector = this.createGraphInspector(options, container);
 
     this.setAbortOnError(options);
     this.registerLoggerConfiguration(options);
@@ -156,7 +157,7 @@ export class NestFactoryStatic {
     options?: NestApplicationContextOptions,
   ): Promise<INestApplicationContext> {
     const container = new NestContainer();
-    const graphInspector = new GraphInspector(container);
+    const graphInspector = this.createGraphInspector(options, container);
 
     this.setAbortOnError(options);
     this.registerLoggerConfiguration(options);
@@ -341,6 +342,15 @@ export class NestFactoryStatic {
     });
     return proxy as unknown as T;
   }
+
+  private createGraphInspector(
+    appOptions: NestApplicationContextOptions,
+    container: NestContainer,
+  ) {
+    return appOptions?.snapshot
+      ? new GraphInspector(container)
+      : NoopGraphInspector;
+  }
 }
 
 /**

packages/testing/testing-module.builder.ts

@@ -2,9 +2,11 @@ import { Logger, LoggerService, Module } from '@nestjs/common';
 import { ModuleMetadata } from '@nestjs/common/interfaces';
 import { ApplicationConfig } from '@nestjs/core/application-config';
 import { NestContainer } from '@nestjs/core/injector/container';
-import { GraphInspector } from '@nestjs/core/inspector/graph-inspector';
 import { MetadataScanner } from '@nestjs/core/metadata-scanner';
 import { DependenciesScanner } from '@nestjs/core/scanner';
+import { NestApplicationContextOptions } from '../common/interfaces/nest-application-context-options.interface';
+import { GraphInspector } from '../core/inspector/graph-inspector';
+import { NoopGraphInspector } from '../core/inspector/noop-graph-inspector';
 import {
   MockFactory,
   OverrideBy,
@@ -18,26 +20,16 @@ import { TestingModule } from './testing-module';
 export class TestingModuleBuilder {
   private readonly applicationConfig = new ApplicationConfig();
   private readonly container = new NestContainer(this.applicationConfig);
-  private readonly graphInspector = new GraphInspector(this.container);
   private readonly injector = new TestingInjector();
   private readonly overloadsMap = new Map();
-  private readonly instanceLoader = new TestingInstanceLoader(
-    this.container,
-    this.injector,
-    this.graphInspector,
-  );
-  private readonly scanner: DependenciesScanner;
   private readonly module: any;
   private testingLogger: LoggerService;
   private mocker?: MockFactory;
 
-  constructor(metadataScanner: MetadataScanner, metadata: ModuleMetadata) {
-    this.scanner = new DependenciesScanner(
-      this.container,
-      metadataScanner,
-      this.graphInspector,
-      this.applicationConfig,
-    );
+  constructor(
+    private readonly metadataScanner: MetadataScanner,
+    metadata: ModuleMetadata,
+  ) {
     this.module = this.createModule(metadata);
   }
 
@@ -71,19 +63,44 @@ export class TestingModuleBuilder {
     return this.override(typeOrToken, true);
   }
 
-  public async compile(): Promise<TestingModule> {
+  public async compile(
+    options: Pick<NestApplicationContextOptions, 'snapshot'> = {},
+  ): Promise<TestingModule> {
     this.applyLogger();
-    await this.scanner.scan(this.module);
+
+    const graphInspector = options?.snapshot
+      ? NoopGraphInspector
+      : new GraphInspector(this.container);
+
+    const scanner = new DependenciesScanner(
+      this.container,
+      this.metadataScanner,
+      graphInspector,
+      this.applicationConfig,
+    );
+    await scanner.scan(this.module);
 
     this.applyOverloadsMap();
-    await this.instanceLoader.createInstancesOfDependencies(
+
+    const instanceLoader = new TestingInstanceLoader(
+      this.container,
+      this.injector,
+      graphInspector,
+    );
+    await instanceLoader.createInstancesOfDependencies(
       this.container.getModules(),
       this.mocker,
     );
-    this.scanner.applyApplicationProviders();
+
+    scanner.applyApplicationProviders();
 
     const root = this.getRootModule();
-    return new TestingModule(this.container, [], root, this.applicationConfig);
+    return new TestingModule(
+      this.container,
+      graphInspector,
+      root,
+      this.applicationConfig,
+    );
   }
 
   private override<T = any>(typeOrToken: T, isProvider: boolean): OverrideBy {

packages/testing/testing-module.ts

@@ -21,16 +21,19 @@ import { Module } from '@nestjs/core/injector/module';
 import { GraphInspector } from '@nestjs/core/inspector/graph-inspector';
 
 export class TestingModule extends NestApplicationContext {
-  protected readonly graphInspector = new GraphInspector(this.container);
+  protected readonly graphInspector: GraphInspector;
 
   constructor(
     container: NestContainer,
-    scope: Type<any>[],
+    graphInspector: GraphInspector,
     contextModule: Module,
     private readonly applicationConfig: ApplicationConfig,
+    scope: Type<any>[] = [],
   ) {
     const options = {};
     super(container, options, contextModule, scope);
+
+    this.graphInspector = graphInspector;
   }
 
   private isHttpServer(