The name of the project is pretty much descriptive enough. To add a little more on the name, the application does the stuff you need from a digital wallet i.e.

1. Registration and Login
2. Account Deposit
3. Account Withdrawal
4. Balance Enquiry
5. Mini Statement

PS. This is fully a backend application with no front end client whatsoever. You can use curl, postman or your favourite http tool to interact with the application.

You can follow the below steps to install and setup the application.

To begin with the application uses postgres as the backend database.

The application uses postgres as the database server. So here are instructions on how to setup postgresql on your machine using docker.

Get the official postgres docker image.

$ docker pull postgres

Then create a container from the image with the following variables

$ docker create \
--name wallet-db \
-e POSTGRES_USER=wallet \
-e POSTGRES_PASSWORD=wallet \
-p 5432:5432 \
postgres

Run the following command to start the container

$ docker start wallet-db

Running the application is as simple as running any other go application but first we need to copy and create our configuration.

$ git clone https://github.com/SirWaithaka/simple-wallet.git

$ cd simple-wallet
$ cp config.yml.example config.yml

This configuration file looks something like this

database:
  host: "127.0.0.1"
  port: "5432"
  user: "wallet"
  password: "wallet"
  dbname: "wallet"

app_secret_key: "eQig7GS4cHO2su"

You can change the config variables depending on your database setup, here i choose to follow the default setup shown at database installation step.

$ cd main
$ go build wallet-server.go
$ ./wallet-server

It will install all dependencies required and produce a binary for your platform.

Make sure you have docker installed and working properly.

$ docker build -t simple-wallet:latest .
$ docker container create --name wallet-server -p 6700:6700 --restart unless-stopped simple-wallet
$ docker container start wallet-server

The server will start at port 6700.

Enjoy.

A description of the api.

All the routes exposed in the application are all defined in this function

func apiRouteGroup(g fiber.Router, domain *registry.Domain, config app.Config) {

	g.Post("/login", user_handlers.Authenticate(domain.User, config))
	g.Post("/user", user_handlers.Register(domain.User))

	g.Get("/account/balance", middleware.AuthByBearerToken(config.Secret), account_handlers.BalanceEnquiry(domain.Account))
	g.Post("/account/deposit", middleware.AuthByBearerToken(config.Secret), account_handlers.Deposit(domain.Account))
	g.Post("/account/withdrawal", middleware.AuthByBearerToken(config.Secret), account_handlers.Withdraw(domain.Account))
	g.Post("/account/withdraw", middleware.AuthByBearerToken(config.Secret), account_handlers.Withdraw(domain.Account))

	g.Get("/account/statement", middleware.AuthByBearerToken(config.Secret), account_handlers.MiniStatement(domain.Transaction))
}

The routes are mounted on the prefix /api so your requests should point to

POST /api/login
POST /api/user # for registration
GET /api/account/balance
POST /api/account/deposit
POST /api/account/withdrawal
GET /api/account/statement

A user can be registered to the api with the following POST parameters firstName, lastName, email, phoneNumber, password

Curl request example

curl --request POST \
  --url http://localhost:6700/api/user \
  --header 'content-type: application/x-www-form-urlencoded' \
  --data firstName=Sir \
  --data lastName=Waithaka \
  --data [email protected] \
  --data phoneNumber=254700000000 \
  --data password=mnbvcxz

Response example

{
    "status": "success",
    "message": "user created",
    "user": {
        "email": "[email protected]",
        "userId": "b4b00501-ba22-49fb-827d-b25d969c58bb"
    }
}

You can use email and password or phoneNumber and password

Curl request example

curl --request POST \
  --url http://localhost:6700/api/login \
  --header 'content-type: application/x-www-form-urlencoded' \
  --data password=mnbvcxz \
  --data phoneNumber=254700000000

Response example

{
    "userId": "84809a02-9082-4ae3-9047-3840948c57cf",
    "token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyIjp7InVzZXJJZCI6Ijg0ODA5YTAyLTkwODItNGFlMy05MDQ3LTM4NDA5NDhjNTdjZiIsImVtYWlsIjoiaGFsbEBlbWFpbC5jb20ifSwiZXhwIjoxNTg0MDI0NTQ0LCJpYXQiOjE1ODQwMDI5NDR9.qZHLJWtYK7_ClgnaPJbGuaiPW8ssd1Ra9xFJWdg6iwE"
}

NOTE: The remaining endpoints require the token acquired above for authentication

You only need the amount parameter

Curl request example

curl --request POST \
  --url http://localhost:6700/api/account/deposit \
  --header 'authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyIjp7InVzZXJJZCI6Ijk4YmNmMmY1LWRiY2ItNDk1NS04NTU0LTc0OWYxMTVhZjU5OCIsImVtYWlsIjoiIn0sImV4cCI6MTYwNDA2Mjg0NiwiaWF0IjoxNjA0MDQxMjQ2fQ.Z0oFwOV3wEiQzpwLg4LH5NZIBUsllDhcJefgvceMiHw' \
  --header 'content-type: application/x-www-form-urlencoded' \
  --data amount=1000

Response example

{
  "balance": 1000,
  "message": "Amount successfully deposited new balance 1000",
  "userId": "98bcf2f5-dbcb-4955-8554-749f115af598"
}

You only need the amount parameter

Curl request example

curl --request POST \
  --url http://localhost:6700/api/account/withdrawal \
  --header 'authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyIjp7InVzZXJJZCI6Ijk4YmNmMmY1LWRiY2ItNDk1NS04NTU0LTc0OWYxMTVhZjU5OCIsImVtYWlsIjoiIn0sImV4cCI6MTYwNDA2OTE0MywiaWF0IjoxNjA0MDQ3NTQzfQ.IYyclrC66aweehs_A4Sigmc83a27udmPofM2yOeut9Q' \
  --header 'content-type: application/x-www-form-urlencoded' \
  --data amount=40

Response example

{
  "balance": 880,
  "message": "Amount successfully withdrawn. New balance 880",
  "userId": "98bcf2f5-dbcb-4955-8554-749f115af598"
}

This is just a GET request, no params

Curl request example

curl --request GET \
  --url http://localhost:6700/api/account/balance \
  --header 'authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyIjp7InVzZXJJZCI6Ijk4YmNmMmY1LWRiY2ItNDk1NS04NTU0LTc0OWYxMTVhZjU5OCIsImVtYWlsIjoiIn0sImV4cCI6MTYwNDA2Mjg0NiwiaWF0IjoxNjA0MDQxMjQ2fQ.Z0oFwOV3wEiQzpwLg4LH5NZIBUsllDhcJefgvceMiHw'

Response example

{
    "message": "Your current balance is 4700",
    "balance": 4700
}

This is just a GET request, no params

Curl request example

curl --request GET \
  --url http://localhost:6700/api/account/statement \
  --header 'authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyIjp7InVzZXJJZCI6Ijk4YmNmMmY1LWRiY2ItNDk1NS04NTU0LTc0OWYxMTVhZjU5OCIsImVtYWlsIjoiIn0sImV4cCI6MTYwNDA2OTE0MywiaWF0IjoxNjA0MDQ3NTQzfQ.IYyclrC66aweehs_A4Sigmc83a27udmPofM2yOeut9Q'

Response example

{
    "message": "ministatement retrieved for the past 5 transactions",
    "userId": "84809a02-9082-4ae3-9047-3840948c57cf",
    "transactions": [
        {
            "transactionId": "1088b880-1aa1-4cf0-929b-dfab01c52c13",
            "transactionType": "balance_enquiry",
            "timestamp": "2020-03-12T13:11:09.863693Z",
            "amount": 4700,
            "userId": "84809a02-9082-4ae3-9047-3840948c57cf",
            "accountId": "fd1ce4e4-e467-4eac-8ea0-ea0c9d4f76fe"
        },
        {
            "transactionId": "8b64ca58-b869-47b6-964a-0846957d4c7f",
            "transactionType": "withdrawal",
            "timestamp": "2020-03-12T12:30:37.355034Z",
            "amount": 4700,
            "userId": "84809a02-9082-4ae3-9047-3840948c57cf",
            "accountId": "fd1ce4e4-e467-4eac-8ea0-ea0c9d4f76fe"
        },
        {
            "transactionId": "4514a94c-f303-4324-b010-a4e7c3dd3f77",
            "transactionType": "withdrawal",
            "timestamp": "2020-03-12T12:30:36.278053Z",
            "amount": 4710,
            "userId": "84809a02-9082-4ae3-9047-3840948c57cf",
            "accountId": "fd1ce4e4-e467-4eac-8ea0-ea0c9d4f76fe"
        },
        {
            "transactionId": "871035ad-456a-4467-8260-414b464b6d86",
            "transactionType": "withdrawal",
            "timestamp": "2020-03-12T12:30:35.446227Z",
            "amount": 4720,
            "userId": "84809a02-9082-4ae3-9047-3840948c57cf",
            "accountId": "fd1ce4e4-e467-4eac-8ea0-ea0c9d4f76fe"
        },
        {
            "transactionId": "c3c3a19a-fc3a-4080-9b52-5d3e19853cd7",
            "transactionType": "withdrawal",
            "timestamp": "2020-03-12T12:30:34.646326Z",
            "amount": 4730,
            "userId": "84809a02-9082-4ae3-9047-3840948c57cf",
            "accountId": "fd1ce4e4-e467-4eac-8ea0-ea0c9d4f76fe"
        }
    ]
}

Tests have not been written for the application but i have very important talks i would share here that i cant recommend enough about how to go about testing the application.

1. Ian Cooper - TDD, Where Did It All Go Wrong

An approach to testing this application would be something in the following lines.

1. Test the code in the interactor files
2. Test the code in the repository files

The above files carry the bulk of the behaviour of the whole application, they are the business logic of the application. The rest of the files are just implementation details that could change rapidly and the tests written for them would certainly fail after change.

e.g. the http handler functions in the application use gofiber, writing unit tests for them is good but not desired, because gofiber can be replaced with mux easily and that would break your tests.