How to test dynamic modules in Nest.js? - testing

Question

My implementation is based on this article: https://dev.to/nestjs/advanced-nestjs-how-to-build-completely-dynamic-nestjs-modules-1370
I want to test my generic, Twilio-based SMS sender service that I share between multiple parts of my application. I want to configure it when I'm importing it from somewhere else, so I'm writing it as a dynamic module. On top of that, the options that I pass to the dynamic module are themselves constructed dynamically, they are read from my .env file. I'm using the factory pattern when I'm registering my provider:
// app.module.ts
#Module({
imports: [
ConfigModule.forRoot({
isGlobal: true,
envFilePath: [
'.env',
],
validationSchema,
}),
SharedSmsModule.registerAsync({
imports: [ConfigModule],
inject: [ConfigService],
useFactory: (configService: ConfigService<EnvironmentVariables>) => {
return {
accountSid: configService.get('TWILIO_ACCOUNT_SID'),
authToken: configService.get('TWILIO_AUTH_TOKEN'),
smsSenderPhoneNumber: configService.get(
'TWILIO_SMS_SENDER_PHONE_NUMBER'
),
};
},
}),
],
})
export class AppModule {}
My shared-sms module calls the function provided in the registerAsync method in app.module.ts:
// shared-sms.module.ts
export interface SharedSmsModuleOptions {
accountSid: string;
authToken: string;
smsSenderPhoneNumber: string;
}
export interface SharedSmsModuleAsyncOptions extends ModuleMetadata {
imports: any[];
inject: any[];
useFactory?: (
...args: any[]
) => Promise<SharedSmsModuleOptions> | SharedSmsModuleOptions;
}
#Module({})
export class SharedSmsModule {
static registerAsync(
sharedSmsModuleAsyncOptions: SharedSmsModuleAsyncOptions
): DynamicModule {
return {
global: true,
module: SharedSmsModule,
imports: sharedSmsModuleAsyncOptions.imports,
providers: [
{
provide: 'SHARED_SMS_OPTIONS',
useFactory: sharedSmsModuleAsyncOptions.useFactory,
inject: sharedSmsModuleAsyncOptions.inject || [],
},
SharedSmsService,
],
exports: [SharedSmsService],
};
}
}
Now I have access to the options variables in my shared-sms.service:
// shared-sms.service
#Injectable()
export class SharedSmsService {
private twilioClient: Twilio;
constructor(
#Inject('SHARED_SMS_OPTIONS') private options: SharedSmsModuleOptions
) {
this.twilioClient = new Twilio(
this.options.accountSid,
this.options.authToken
);
}
async sendSms(sendSmsDto: SendSmsDto): Promise<MessageInstance> {
await validateOrReject(plainToInstance(SendSmsDto, sendSmsDto));
const smsData = {
from: this.options.smsSenderPhoneNumber,
to: sendSmsDto.to,
body: sendSmsDto.body,
};
return await this.twilioClient.messages.create(smsData);
}
}
So long everything seems to be working. But I'm having issues when I'm trying to test the service's sendSms function. I can write tests that work when I'm providing hardcoded Twilio test account values in my test file. But I don't want to commit them to the repository, so I would want to get them from my .env file. I have tried providing everything to the Test.createTestingModule function when I'm creating my moduleRef, based on what I did in the code that I already wrote, but I couldn't specify the Twilio test account values dynamically. As I don't see documentation regarding this issue, I feel like that I'm either missing a conceptual point (providing so many things in the test seems like an overkill) or there is a trivial work-around. Please help me figure out how to pass those values to my tests from my .env file