# Copeiro [](https://github.com/fbeline/copeiro/actions/workflows/elixir.yml)
<img align="left" height="300" src="https://user-images.githubusercontent.com/5730881/116327729-cf9fea00-a79d-11eb-9be4-d4fa5ece38ae.jpg">
## Motivation
Very often we need to iterate and transform results while writing tests and asserting lists.
This data manipulation inside test statements becomes a repetitive task as the project grows. Making tests less readable and increasing the chances of mistakes.
The Copeiro main goal is to extend the ExUnit with an idiomatic DSL that seamless integrates to it.
```elixir
assert_lists [{:c, 3}, {:a, 1}] in [{:c, 3}, {:b, 2}, {:a, 1}]
```
## Installation
```elixir
def deps do
[
{:copeiro, "~> 0.1.1", only: :test}
]
end
```
## Usage
Using Copeiro in a test file
```elixir
def HelloWorldTest do
use ExUnit.Case, async: true
import Copeiro
# ...
end
```
Adding Copeiro to your [CaseTemplate](https://hexdocs.pm/ex_unit/ExUnit.CaseTemplate.html) _(recommended)_
```elixir
defmodule MyCase do
use ExUnit.CaseTemplate
using do
quote do
# This code is injected into every case that calls "use MyCase"
import Copeiro
end
end
end
```
## Examples
For the following examples `LEFT` and `RIGHT` will be used to describe the expression:
`assert_lists LEFT OPERATOR RIGHT`
### All elements of `LEFT` are also elements of `RIGHT`
```elixir
iex> assert_lists [1, 2] in [0, 2, 1, 3]
true
iex> assert_lists [{:b, 2}, {:a, 1}] in [{:a, 1}, {:b, 2}, {:c, 3}]
true
```
### `LEFT` and `RIGHT` has no element in common
```elixir
iex> assert_lists [1, 2] not in [3, 4]
true
iex> assert_lists [%{c: 3}, %{d: 4}] not in [%{a: 1}, %{b: 2}]
true
```
### Asserts that two lists match in any order
```elixir
iex> assert_lists [1, 2, 3] == [2, 1, 3], any_order: true
true
iex> assert_lists [{:a, 0}, {:b, 1}, {:c, 3}] == [{:a, 0}, {:c, 3}, {:b, 1}], any_order: true
true
```
### Asserting lists of maps/structs
When asserting maps and or structs you can compose the expression with `keys`
```elixir
iex> assert_lists [%{a: 1}, %{a: 2}] in [%{a: 1, b: 1}, %{a: 2, b: 2}, %{a: 3, b: 3}], keys: [:a]
true
iex> assert_lists [%Person{name: "john", age: 20}] == [%Person{name: "Jane", age: 20}], keys: [:age]
true
```
## Helpful error messages
```
assert_lists [%{d: 4}, %{a: 1}] not in [%{a: 1}, %{b: 2}]
match succeeded, but should have failed
value: %{a: 1}
left: [%{d: 4}, %{a: 1}]
right: [%{a: 1}, %{b: 2}]
```
## License
MIT License
Copyright (c) 2021 Felipe Beline Baravieira
