Emulator Ready Firebase Function Queues (using Nest.js)

util.module.ts

const adminApp = admin.initializeApp();

@Global()
@Module({
    providers: [
        {
            provide: Functions,
            useFactory: () => {
                if (process.env.FUNCTIONS_EMULATOR) {
                    // since functions emulator does not know queues or the port is blocked because of this very request
                    // we call our function directly
                    const logger = new Logger("Functions Factory");
                    logger.debug("Recognized Emulator environment. Stubbing Queues");
                    Object.assign(TaskQueue.prototype, {
                        enqueue: async function (data: never): Promise<void> {
                            return new Promise((resolve, reject) => {
                                const functionNameSegments = this.functionName.split("/");
                                const functionName = functionNameSegments.length > 1
                                    ? functionNameSegments.pop()
                                    : this.functionName;
                                const queue = main[functionName]; // <- this references the main.ts declaring the queues and functions
                                if (queue) {
                                    const httpBody = JSON.parse(JSON.stringify(data));
                                    return resolve(queue.run(httpBody));
                                } else {
                                    logger.error("No such queue" + this.functionName);
                                    reject();
                                }
                            });
                        }
                    });
                }

                return getFunctions(adminApp);
            }
        }
    ],
    exports: [
        Functions
    ]
})
export class UtilModule {
}