spec2

# spec2 [![Build Status](https://travis-ci.org/waterlink/spec2.cr.svg)](https://travis-ci.org/waterlink/spec2.cr)

Enhanced `spec` testing library for [Crystal](http://crystal-lang.org/).

## Example

```crystal
Spec2.describe Greeting do
  subject { Greeting.new }

  describe "#greet" do
    context "when name is world" do
      let(name) { "world" }

      it "greets the world" do
        expect(subject.greet(name)).to eq("Hello, world")
      end
    end
  end
end
```

## Installation

Add it to `shard.yml`

```yml
dependencies:
  spec2:
    github: waterlink/spec2.cr
    version: ~> 0.9
```

## Goals

- No global scope pollution
- No `Object` pollution
- Ability to run examples in random order
- Ability to specify `before` and `after` blocks for example
  group
- Ability to define `let`, `let!`, `subject` and `subject!`
  for example group

## Roadmap

### `1.0`

- [ ] Configuration through CLI interface.
- [ ] Filters.
- [ ] Shared examples and example groups.

## Usage

```crystal
require "spec2"
```

### Top-level describe

```crystal
Spec2.describe MySuperLibrary do
  describe Greeting do
    # .. example groups and examples here ..
  end
end
```

If you have test suite written for `Spec` and you don't want to prefix each
top-level describe with `Spec2.`, you can just include `Spec::GlobalDSL`
globally:

```crystal
include Spec2::GlobalDSL

# and then:
describe Greeting do
  # ...
end
```

### Writing examples

```crystal
Spec2.describe "some tests" do
  it "is a test name here" do
    # .. this is the example here ..
  end

  pending "is a pending test here" do
    # .. this example will not be executed ..
  end
end
```

### `Expect` syntax

```crystal
expect(greeting.for("john")).to eq("hello, john")
```

If you have big codebase that runs on `Spec`, you can use this to
enable `#should` and `#should_not` on `Object`:

```crystal
Spec2.enable_should_on_object
```

### List of builtin matchers

- `eq("hello, world")` - asserts actual is equal to expected
- `raise_error(ErrorClass [, message_matcher])` - checks if block raises
  expected error
- `be(42)` - asserts actual is the same as expected
- `match(/hello .+/)` - asserts actual is matching provided regexp
- `be_true` - asserts actual is equal `true`
- `be_false` - asserts actual is equal `false`
- `be_truthy` - asserts actual is not `nil` or `false`
- `be_falsey` - asserts actual is `nil` or `false`
- `be_nil` - asserts actual is equal `nil`
- `be_close(42, 0.01)` - asserts actual is in delta-proximity of expected
- `expect(42).to_be < 45` - asserts arbitrary method call on actual to be
  truthy
- `be_a(String)` - asserts actual to be of expected type (uses `is_a?`)

### Random order

```crystal
Spec2.random_order

# this is what happens under the hood
Spec2.configure_order(Spec2::Orders::Random)
```

To configure your own custom order you can use:

```crystal
Spec2.configure_order(MyOrder)
```

Class `MyOrder` should implement `Order` protocol and `Order::Factory` class
protocol ([see it here](src/order.cr)).
See also [a random order implementation](src/orders/random.cr).

### No color mode

```crystal
Spec2.nocolor

# this is what happens under the hood
Spec2.configure_output(Spec2::Outputs::Nocolor)
```

To configure your own custom output you can use:

```crystal
Spec2.configure_output(MyOutput)
```

Class `MyOutput` should implement `Output` protocol and `Output::Factory` class
protocol ([see it here](src/output.cr)).
See also [a default colorful output implementation](src/outputs/default.cr).

### Documentation reporter

```crystal
Spec2.doc

# this is what happens under the hood
Spec2.configure_reporter(Spec2::Reporters::Doc)
```

To configure your own custom reporter you can use:

```crystal
Spec2.configure_reporter(MyReporter)
```

Class `MyReporter` should implement `Reporter` protocol and `Reporter::Factory`
class protocol ([see it here](src/reporter.cr)).
See also [a default reporter implementation](src/reporters/default.cr).

If you are creating a custom reporter, you might want to use `ElapsedTime`
class to report elapsed time for the test suite. Example usage:

```crystal
output.puts "Finished in #{::Spec2::ElapsedTime.new.to_s}"
```

### Configuring custom Runner

```crystal
Spec2.configure_runner(MyRunner)
```

Class `MyRunner` should implement `Runner` protocol and `Runner::Factory` class
protocol ([see it here](src/runner.cr)).
See also [a default runner implementation](src/runners/default.cr).

### `before`

`before` - register a hook that is run before any example in current and all
nested contexts.

```crystal
before { .. do some stuff .. }
```

### `after`

`after` - register a hook that is run after any successful example in current
and all nested contexts.

```crystal
after { .. do some stuff .. }
```

### `let`

`let(name) { value }` - register a binding of certain `value` to `name`. Lazy:
provided block will only be evaluated when needed in example and only once per
example.

```crystal
let(answer) { 42 }

it "is correct answer" do
  expect(answer).to eq(42)
end
```

### `let!`

`let(name) { value }` - register a binding of certain `value` to `name`. It is
not lazy: provided block will be evaluated before each example exactly once.

```crystal
let!(answer) { 42 }

it "is correct answer" do
  expect(answer).to eq(42)
end
```

### `described_class`

For `describe ...` blocks, that describe a class, there is a shortcut to reference that class:

```crystal
describe Example do
  it "can be created" do
    expect(described_class.new.greet).to eq("hello world")
    # instead of `Example.new.greet`.
  end
end
```

### `subject`

`subject { value }` - register a subject of your test with provided `value`.
Lazy.

```crystal
subject { Stuff.new }

it "works" do
  expect(subject.answer).to eq(42)
end
```

`subject(name) { value }` - registers a named subject of your test with
provided `value` with provided `name`. Lazy.

```crystal
subject(stuff) { Stuff.new }

it "works" do
  expect(stuff.answer).to eq(42)
end
```

### `subject!`

`subject! { value }` - register a subject of your test with provided `value`.
It is not lazy.

```crystal
subject! { Stuff.new }

it "works" do
  expect(subject.answer).to eq(42)
end
```

`subject!(name) { value }` - registers a named subject of your test with
provided `value` with provided `name`. It is not lazy.

```crystal
subject!(stuff) { Stuff.new }

it "works" do
  expect(stuff.answer).to eq(42)
end
```

### `delayed`

Use `delayed { ... }` to verify expectations after test example and its `after`
hooks finish. Example:

```crystal
it "does something interesting eventually" do
  delayed { expect(value).to eq(42) }
  # .. do something else, that should eventually lead to value == 42 ..
end
```

### Custom matchers

First, define your matcher implementing [this protocol](src/matcher.cr):

```crystal
class MyMatcher(T, E)
  include Spec2::Matcher

  @actual_inspect : String?

  def initialize(@expected : T, @stuff : E)
  end

  def match(actual)
    @actual_inspect = actual.inspect

    # return true or false here
  end

  def failure_message
    "Expected to be valid #{@stuff.inspect}.
    Expected: #{@expected.inspect}.
    Actual:   #{@actual_inspect}."
  end

  def failure_message_when_negated
    "Expected to be invalid #{@stuff.inspect}.
    Expected: #{@expected.inspect}.
    Actual:   #{@actual_inspect}."
  end

  def description
    "(stuff in #{@expected} #{stuff})"
  end
end
```

And then, register shortcut helper method to use your matcher.

```crystal
Spec2.register_matcher(stuff) do |stuff, expected|
  MyMatcher.new(expected, stuff)
end
```

And use it:

```crystal
describe "stuff" do
  it "is valid stuff" do
    expect(something).to stuff(some_stuff, "expected stuff")
  end
end
```

## Development

After you forked the repo:

- run `crystal deps` to install dependencies
- run `crystal spec` and `crystal unit` to see if tests are green
  (or just run `scripts/test` to run them both)
- apply TDD to implement your feature/fix/etc

## Contributing

1. Fork it ( https://github.com/waterlink/spec2.cr/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

## Contributors

- [waterlink](https://github.com/waterlink) Oleksii Fedorov - creator, maintainer