refactor(common,core): support read-only arrays on module metadata

Add support for ModuleMetadata to accept ReadOnlyArray. This allows developers to use TypeScript const assertions for module definitions.

There are no breaking changes with this commit and this change is discussed in #13326.

packages/common/interfaces/modules/module-metadata.interface.ts

@@ -16,7 +16,7 @@ export interface ModuleMetadata {
    * Optional list of imported modules that export the providers which are
    * required in this module.
    */
-  imports?: Array<
+  imports?: ReadonlyArray<
     Type<any> | DynamicModule | Promise<DynamicModule> | ForwardReference
   >;
   /**
@@ -33,7 +33,7 @@ export interface ModuleMetadata {
    * Optional list of the subset of providers that are provided by this module
    * and should be available in other modules which import this module.
    */
-  exports?: Array<
+  exports?: ReadonlyArray<
     | DynamicModule
     | Promise<DynamicModule>
     | string

packages/core/injector/container.ts

@@ -173,7 +173,10 @@ export class NestContainer {
     await this.addDynamicModules(imports, scope);
   }
 
-  public async addDynamicModules(modules: any[], scope: Type<any>[]) {
+  public async addDynamicModules(
+    modules: ReadonlyArray<any>,
+    scope: Type<any>[],
+  ) {
     if (!modules) {
       return;
     }

packages/core/test/injector/container.spec.ts

@@ -210,6 +210,16 @@ describe('NestContainer', () => {
         expect(addModuleSpy.called).to.be.true;
       });
     });
+    describe('when array is readonly', () => {
+      it('should call "addModule"', () => {
+        const addModuleSpy = sinon.spy(container, 'addModule');
+
+        const readonlyModules: ReadonlyArray<any> = Object.freeze([Test]);
+        container.addDynamicModules(readonlyModules, []);
+
+        expect(addModuleSpy.called).to.be.true;
+      });
+    });
   });
 
   describe('get applicationConfig', () => {