order-up

Code candidates will extend as part of their technical interview process. The order-up service handles all order-specific calls including creating orders, checking the status on orders, etc. This service is part of a larger microservice backend for a online marketplace.

Getting started

You also will need to install Go. Then clone this this repository and run go mod tidy within this repository to download all necessary dependencies locally.

Project Structure

Top-level

The top-level only contains a single main.go file which holds the main function. If you ran go build ./. that would produce a order-up binary that would start by executing the main function in main.go.

api package

The api package handles incoming HTTP requests with a REST paradigm and calls various functions based on the path. This package uses the storage package to perform the necessary functionality for each API call. The tests use a mocked storage instance.

storage package

The storage package contains the database calls necessary for persisting and retrieving orders. The methods are missing the bodies of the functions since you're expected to fill them in with whatever database and implementation you think satisfies the tests and documented functionality.

mocks package

The mocks package just contains a helper function for mocking an external service by accepting an http.Handler and returning a *http.Client as well as generated code for mocking a *storage.Instance. This simply makes the tests easier in the api package.

Relevant Go commands

• go mod tidy downloads all dependencies and update go.mod file with any new dependencies
• go test -v -race ./... tests all files and subdirectories. You can instead do go test -v ./storage/... to only test the storage package. Any public function with the format TestX(*testing.T) will automatically be called by go test. Typically these functions are placed in X_test.go files. You can pass a regex to -run like -run ^TestInsertOrder$ in order to just run tests matching the regex.
• go fmt ./... reformats the go files according to the gofmt spec
• go vet ./... prints out most-likely errors or mistakes in Go code
• go get $package adds a new dependency to the current project

Databases

The easiest way to run databases locally for testing is using Docker. You can use any database you're familiar with these are just some examples.

Alternatively you can sign up for an online free tier of a hosted version of these databases (like MongoDB Atlas, or CockroachDB Cloud) if that's easier.

MongoDB

docker run --rm -it -p 27017:27017 mongo

PostgreSQL

docker run --rm -it -p 5432:5432 -e POSTGRES_PASSWORD=password postgres

Redis

docker run --rm -it -p 6379:6379 redis

Relevant Database Packages

You can use any database or driver you're familiar with these are just some examples.

• mongo and the companion bson. See this tutorial.
• database/sql but this must be combined with a driver package like pq. See this tutorial
• radix Redis driver

Remember when you're adding new packages to run go mod tidy to ensure the go.mod and go.sum files are updated.