How to perform TDD and CI in Julia?

# How to perform TDD and CI in Julia?

#### Speaker: Yueh-Hua Tu

##### 2021.1.14

---

## Test-driven development

> Wikipedia: Test-driven development

---

## Test-driven development

* Testing is to guide development

* Need a efficient way to test

* Refuel for example

```
sh> julia --proj
(Refuel) pkg> test
```

---

## Start from generating a project

```julia
using PkgTemplates

t = Template(;
    user="yuehhua",
    dir="/media/yuehhua/Workbench/workspace",
    authors="Yueh-Hua Tu",
    julia=v"1.5",
    plugins=[
        License(; name="MIT"),
        Git(; manifest=true, ssh=true),
        GitHubActions(),
        Codecov(),
        Documenter{GitHubActions}(),
        Develop(),
        TagBot()
    ],
)

t("MyProject")
```

---

## Project layout

```julia
.
├── docs
│   ├── make.jl
│   ├── Manifest.toml
│   ├── Project.toml
│   └── src
│       └── index.md
├── LICENSE
├── Manifest.toml
├── Project.toml
├── README.md
├── src
│   └── MyProject.jl
└── test
    └── runtests.jl

4 directories, 10 files
```

---

## Write testing

##### test/runtests.jl

```julia
using MyProject
using Test

@testset "MyProject.jl" begin
    @test foo() == "Hello, world!"
end
```

---

## Write your code

##### src/MyProject.jl

```julia
module MyProject

foo() = "Hello, world!"

end
```

---

## Fail!?

```julia
MyProject.jl: Error During Test at /media/yuehhua/Workbench/workspace/MyProject/test/runtests.jl:5
  Test threw exception
  Expression: foo() == "Hello, world!"
  UndefVarError: foo not defined
  Stacktrace:
   [1] top-level scope at /media/yuehhua/Workbench/workspace/MyProject/test/runtests.jl:5
   [2] top-level scope at /build/julia/src/julia-1.5.3/usr/share/julia/stdlib/v1.5/Test/src/Test.jl:1115
   [3] top-level scope at /media/yuehhua/Workbench/workspace/MyProject/test/runtests.jl:5
```

#### Remember to export functions

```julia
module MyProject

export foo

foo() = "Hello, world!"

end
```

---

## Congratulation! Test passed!

```julia
Test Summary: | Pass  Total
MyProject.jl  |    1      1
    Testing MyProject tests passed
```

---

## Commit your code

* If the development is sufficient for a commit, just submit your commit to repository.

* If the submission triggers CI to start, check if CI is success.

---

## What's next?

Configure your CI server!

#### Free for open source

* Travis CI
  * Circle CI
  * Github Action
  * Gitlab CI

#### Self-hosted CI

* Jenkins
  * Gitlab CI

#### Let's check demo

---

# Thank you for attention