github.com/jenkins-x/jx/v2@v2.1.155/CONTRIBUTING.MD

# Hacking on JX

This guide is for developers who want to improve the Jenkins X jx CLI. These instructions will help you set up a
development environment for working on the jx source code.

## Prerequisites

To compile, test and contribute towards the jx binaries you will need:

 - [git][]
 - [Go][] 1.11, 1.12 or 1.13, with support for compiling to `linux/amd64` (Go version 1.14 is at the moment not supported).
 - [dep](https://github.com/golang/dep)
 - [pre-commit](https://pre-commit.com) _optional: we use [detect-secrets](https://github.com/Yelp/detect-secrets) to help prevent secrets leaking into the code base_
 

In most cases, install the prerequisite according to its instructions. See the next section
for a note about Go cross-compiling support.

### Configuring Go

The jx's binary eCLI is  built on your machine in your GO Path. 

On macOS, Go can be installed with [Homebrew][]:

```shell

$ brew install go 
```

It is also straightforward to build Go from source:

```shell
$ sudo su
$ curl -sSL https://storage.googleapis.com/golang/go1.7.5.src.tar.gz | tar -C /usr/local -xz
$ cd /usr/local/go/src
$ # compile Go for the default platform first, then add cross-compile support
$ ./make.bash --no-clean
$ GOOS=linux GOARCH=amd64 ./make.bash --no-clean
```

## Fork the Repository

Begin at Github by forking jx, then clone your fork locally. Since jx is a Go package, it
should be located at `$GOPATH/src/github.com/jenkins-x/jx`.

```shell
$ mkdir -p $GOPATH/src/github.com/jenkins-x
$ cd $GOPATH/src/github.com/jenkins-x
$ git clone git@github.com:<username>/jx.git
$ cd jx
```

Add the conventional [upstream][] `git` remote in order to fetch changes from jx's main master
branch and to create pull requests:

```shell
$ git remote add upstream https://github.com/jenkins-x/jx.git
```

## Build Your Changes

With the prerequisites installed and your fork of jx cloned, you can make changes to local jx
source code.

Run `make` to build the `jx`  binaries:

```shell

$ make build      # runs dep and builds `jx`  inside the build/
```

## Testing

The jx test suite is divided into three sections:
 - The standard unit test suite
 - Slow unit tests
 - Integration tests

To run the standard test suite:
```make test```

To run the standard test suite including slow running tests:
```make test-slow```

To run all tests including integration tests (NOTE These tests are not encapsulated):
```make test-slow-integration```


To get a nice HTML report on the tests:
```make test-report-html```

### Writing tests

### Unit Tests

Unit tests should be isolated (see what is an unencapsulated test), and should contain the `t.Parallel()` directive in order to keep things nice and speedy.

If you add a slow running (more than a couple of seconds) test, it needs to be wrapped like so:
```
if testing.Short() {
	t.Skip("skipping a_long_running_test")
} else {
	// Slow test goes here...
}
```
Slows tests can (and should) still include `t.Parallel()`

Best practice for unit tests is to define the testing package appending _test to the name of your package, e.g. `mypackage_test` and then import `mypackage` inside your tests.
This encourages good package design and will enable you to define the exported package API in a composable way.

### Integration Tests

To add an integration test, create a separate file for your integration tests using the naming convention `mypackage_integration_test.go` Use the same package declaration as your unit tests: `mypackage_test`. At the very top of the file before the package declaration add this custom build directive:

```
// +build integration

```
Note that there needs to be a blank line before you declare the package name. 

This directive will ensure that integration tests are automatically separated from unit tests, and will not be run as part of the normal test suite.
You should NOT add `t.Parallel()` to an unencapsulated test as it may cause intermittent failures.

### What is an unencapsulated test?
A test is unencapsulated (not isolated) if it cannot be run (with repeatable success) without a certain surrounding state. Relying on external binaries that may not be present, writing or reading from the filesystem without care to specifically avoid collisions, or relying on other tests to run in a specific sequence for your test to pass are all examples of a test that you should carefully consider before committing. If you would like to easily check that your test is isolated before committing simply run: `make docker-test`, or if your test is marked as slow: `make docker-test-slow`. This will mount the jx project folder into a golang docker container that does not include any of your host machines environment. If your test passes here, then you can be happy that the test is encapsulated.

### Mocking / Stubbing
Mocking or stubbing methods in your unit tests will get you a long way towards test isolation. Coupled with the use of interface based APIs you should be able to make your methods easily testable and useful to other packages that may need to import them.
https://github.com/petergtz/pegomock Is our current mocking library of choice, mainly because it is very easy to use and doesn't require you to write your own mocks (Yay!)
We place all interfaces for each package in a file called `interface.go` in the relevant folder. So you can find all interfaces for `github.com/jenkins-x/jx/v2/pkg/util` in `github.com/jenkins-x/jx/v2/pkg/util/interface.go` 
Generating/Regenerating a mock for a given interface is easy, just go to the `interface.go` file that corresponds with the interface you would like to mock and add a comment directly above your interface definition that will look something like this:
```
// CommandInterface defines the interface for a Command
//go:generate pegomock generate github.com/jenkins-x/jx/v2/pkg/util CommandInterface -o mocks/command_interface.go
type CommandInterface interface {
	DidError() bool
	DidFail() bool
	Error() error
	Run() (string, error)
	RunWithoutRetry() (string, error)
	SetName(string)
	SetDir(string)
	SetArgs([]string)
	SetTimeout(time.Duration)
	SetExponentialBackOff(*backoff.ExponentialBackOff)
}
```
In the example you can see that we pass the generator to use: `pegomock generate` the package path name: `github.com/jenkins-x/jx/v2/pkg/util` the name of the interface: `CommandInterface` and finally an output directive to write the generated file to a mock subfolder. To keep things nice and tidy it's best to write each mocked interface to a separate file in this folder. So in this case: `-o mocks/command_interface.go`

Now simply run:
```
go generate ./...
```
or
```
make generate
```

You now have a mock to test your new interface!
The new mock can now be imported into your test file and used for easy mocking/stubbing.
Here's an example:
```
package util_test

import (
	"errors"
	"testing"

	"github.com/jenkins-x/jx/v2/pkg/util"
	mocks "github.com/jenkins-x/jx/v2/pkg/util/mocks"
	. "github.com/petergtz/pegomock"
	"github.com/stretchr/testify/assert"
)

func TestJXBinaryLocationSuccess(t *testing.T) {
	t.Parallel()
	commandInterface := mocks.NewMockCommandInterface()
	When(commandInterface.RunWithoutRetry()).ThenReturn("/test/something/bin/jx", nil)

	res, err := util.JXBinaryLocation(commandInterface)
	assert.Equal(t, "/test/something/bin", res)
	assert.NoError(t, err, "Should not error")
}
```
Here we're importing the mock we need in our import declaration:
```
mocks "github.com/jenkins-x/jx/v2/pkg/util/mocks"
```
Then inside the test we're instantiating `NewMockCommandInterface` which was automatically generated for us by pegomock.

Next we're stubbing something that we don't actually want to run when we execute our test. In this case we don't want to make a call to an external binary as that could break our tests isolation. We're using some handy matchers which are provided by pegomock, and importing using a `.` import to keep the syntax neat (You probably shouldn't do this outside of tests):
```
When(commandInterface.RunWithoutRetry()).ThenReturn("/test/something/bin/jx", nil)
```
Now when we can setup our  test using the mock interface and make assertions as normal.


### Debug logging

Lots of the test have debug output to try figure out when things fail. You can enable verbose debug logging for tests via

```shell 
export JX_TEST_DEBUG=true
```

## Debugging

First you need to [install Delve](https://github.com/derekparker/delve/blob/master/Documentation/installation/README.md)

Then you should be able to run a debug version of a jx command:

```
dlv --listen=:2345 --headless=true --api-version=2 exec ./build/jx -- some arguments
```

Then in you IDE you should be able to then set a breakpoint and connect to `2345`.

e.g. in IntellJ you create a new `Go Remote` execution and then hit `Debug`

### Debugging jx with stdin

If you want to debug using `jx` with `stdin` to test out terminal interaction, you can start `jx` as usual from the command line then:

* find the `pid` of the jx command via something like `ps -elaf | grep jx`
* start Delve attaching to the pid:

```shell

dlv --listen=:2345 --headless=true --api-version=2 attach SomePID
```

### Debugging a unit test

You can run a single unit test via

```shell
export TEST="TestSomething"
make test1
```

You can then start a Delve debug session on a unit test via:

```shell
export TEST="TestSomething"
make debugtest1
```

Then set breakpoints and debug in your IDE like in the above debugging.

### Using a helper script

If you create a bash file called `jxDebug` as the following (replacing `SomePid` with the actual `pid`):

```bash
#!/bin/sh
echo "Debugging jx"
dlv --listen=:2345 --headless=true --api-version=2 exec `which jx` -- $*
```

Then you can change your `jx someArgs` CLI to `jxDebug someArgs` then debug it!

## Pre-commit Hooks

These are installed as a git 'pre-commit' hook and it operates automatically via a hook when using the `git commit` command. To setup this hook:
* Install [pre-commit](https://pre-commit.com/#install)
* Once installed, ensure you're at the root of this repository where the `.pre-commit-config.yaml` file exists, then:

```bash
pre-commit install
```

If you wish to find out more:
- [pre-commit](https://pre-commit.com)
- [git hooks](https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks)

[git]: https://git-scm.com/
[dep]: https://github.com/golang/dep 
[go]: https://golang.org/
[Homebrew]: https://brew.sh/
[Kubernetes]: https://github.com/kubernetes/kubernetes
[upstream]: https://help.github.com/articles/fork-a-repo/
[upx]: https://upx.github.io