This Gist is a part of the Article: https://prokash-sarkar.medium.com/unit-testing-with-dagger-2-brewing-a-potion-with-fakes-mocks-and-custom-rules-in-android-7f0ab7b22cb

NetworkModule.kt

@Module
class NetworkModule {
    @Singleton
    @Provides
    fun provideHttpLoggingInterceptor(): HttpLoggingInterceptor {
        return HttpLoggingInterceptor()
            .setLevel(HttpLoggingInterceptor.Level.BODY)
    }
    @Singleton
    @Provides
    fun provideOkHttpClient(
        loggingInterceptor: HttpLoggingInterceptor
    ): OkHttpClient {
        return OkHttpClient.Builder()
            .connectTimeout(30, TimeUnit.SECONDS)
            .writeTimeout(40, TimeUnit.SECONDS)
            .readTimeout(60, TimeUnit.SECONDS)
            .addInterceptor(loggingInterceptor)
            .build()
    }
    @Singleton
    @Provides
    fun provideGson(): Gson {
        val gson = GsonBuilder()
            .setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
            .create()
        return gson
    }
    @Singleton
    @Provides
    fun provideMoshi(): Moshi {
        val moshi = Moshi.Builder()
            .add(KotlinJsonAdapterFactory())
            .build()
        return moshi
    }
    @Singleton
    @Provides
    fun provideRetrofit(
        gson: Gson,
        moshi: Moshi,
        okHttpClient: OkHttpClient,
    ): Retrofit {
        return Retrofit.Builder()
            .addConverterFactory(GsonConverterFactory.create(gson))
            .addConverterFactory(MoshiConverterFactory.create(moshi))
            .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
            .baseUrl("https://api.github.com/")
            .client(okHttpClient)
            .build()
    }
    @Singleton
    @Provides
    fun provideApiClient(retrofit: Retrofit): ApiService = retrofit.create(ApiService::class.java)
}