Project goals

Requirements of the online bank system program:

Enable customers to create an account.
Enable customers to withdraw money.
Enable customers to transfer money to another account.
Provide an account statement with customer data and a final balance.
Expose a Web API through an endpoint to print an account statement.

The interaction with the core package will be through a CLI program.

Project structure

We’ll create a Go package for all the bank core logic and a main program to initialize the system with a few customers and actions like deposits and transfers. Additionally, this main program will start a Web API server to expose an endpoint for the account statement.

$GOPATH/
  src/
    bankcore/
      go.mod
      bank.go
    bankapi/
      go.mod
      main.go

Let’s start creating a dummy bankcore/bank.go package.

package bank

func Hello() string {
    return "Hey! I'm working!"
}

We have to define the bankcore/go.mod file to tell the Go compiler that we’re using the bankcore package.

module github.com/msft/bank

go 1.14

Regarding the bankapi, let’s use the bankcore local package:

// src/bankapi/main.go
package main

import (
    "fmt"

    "github.com/msft/bank"
)

func main() {
    fmt.Println(bank.Hello())
}

Where in src/bankapi/go.mod we indicate about the package we are using:

module bankapi

go 1.14

require (
    github.com/msft/bank v0.0.1
)

replace github.com/msft/bank => ../bankcore

Let’s add some tests

Next to each XXX.go file we can add a XXX_test.go file with the same name and the _test suffix.

// bankcore/bank_test.go
package bank

import "testing"

func TestAccount(t *testing.T) {

}

To run the tests

go test -v

Run all *_test.go files.

Next: part II