These guidelines for writing Go code are WIP

Overview

This document covers common coding styles and guidelines for all ForgeRock products.

Copyright notices

Within the FRaaS codebases we are not currently adding licence headers to individual source files.  This practice diverges from the standard practice of doing so across other projects.

The ForgeRock Go coding style

Quick dos/donts

Documentation

Source code layout

In addition to good documentation, having a consistent approach to organising code across directories and within a given source file makes it easier for engineers to move between projects and get up to speed quickly.

Linting rules

Where possible, agreed standards relating to source files should be enforced by linting during continuous integration.  The linting rules currently in use by the FRaaS team are:

linters:
  # inverted configuration with `enable-all` and `disable` is not scalable during updates of golangci-lint
  disable-all: true
  enable:
    - deadcode
    - errcheck
    - gofmt
    - goimports
    - gosimple
    - govet
    - ineffassign
    - structcheck
    - typecheck
    - unused
    - varcheck

run:
  tests: true

Logging

Idiomatic Go

In addition to the points raised above, we should endeavour to write idiomatic Go.  Guidance for what these idioms are and how to follow them can be found in:

Mocking

Mocking is done using https://github.com/vektra/mockery which generates mocks using https://github.com/stretchr/testify.

What not to do
Generating mocks

When adding a new interface that will require a mock there are a few simple steps to follow

  1. Follow the instructions to install mockery
  2. Add a line either above the interface you've added or in a package.go file alongside the interface with a 'go generate' comment
  3. Run 'go generate ./...' in the relevant folder - this will run 'mockery' and generate a mock for your interface under the 'mocks' folder

Your interface should look like this:

//go:generate mockery --all

// ThingDoer does a thing
type ThingDoer interface {
	DoThing() (error)
}

If you need to generate a mock for an interface but you also need to use that mock in the same package, this will cause import cycles. To get around this, add '--inpackage' to the list of arguments to 'mockery' in the generate comment.

Using mocks

If you want to use one of these mocks in one of your tests, there is a small utility function in go/common/pkg/testutil/mockhelper.go which can be used to do some common setup and mock assertion. An example of how to use this:


func TestSomething(t *testing.T) {
	// create mock controller
	ctrl := testutil.NewController(t)
	// defer 'finish' - this will check that your mock assertions are satisfied
	defer ctrl.Finish()

	// Create the mock object
	mockThingdoer := &mocks.Thingdoer{}

	// register the mock object with the controller - this will prevent mock assertions from instantly panicking, and will check for assertions at the end of the test
	ctrl.Register(&mockThingdoer.Mock)

	// Set mock assertions
	mockThingDoer.On("DoThing").Return(nil)

	// call your function, do basic checks
	err := useThingdoer(mockThingdoer)
	assert.NoError(t, err)

	// If 'DoThing' was not called, mockery will fail the test when the function ends
}


The testify documentation will have more information about what methods these mocks will have and how to use them.

Commonly used libraries