![reek logo](logo/reek.text.png)

# Code smell detector for Ruby

## Overview


[![Build Status](https://secure.travis-ci.org/troessner/reek.svg?branch=master)](https://travis-ci.org/troessner/reek?branch=master)
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[![Dependency Status](https://gemnasium.com/troessner/reek.png)](https://gemnasium.com/troessner/reek)
[![Inline docs](https://inch-ci.org/github/troessner/reek.png)](https://inch-ci.org/github/troessner/reek)

## Quickstart

Reek is a tool that examines Ruby classes, modules and methods and reports any
[Code Smells](docs/Code-Smells.md) it finds.

For an excellent introduction to
[Code Smells](docs/Code-Smells.md) and `Reek` check out [this blog post](https://blog.codeship.com/how-to-find-ruby-code-smells-with-reek/)
or [that one](https://troessner.wordpress.com/2016/01/01/the-latest-and-greatest-additions-to-reek/). There is also [this talk](https://www.youtube.com/watch?v=ZzqOuHI5MkA) from the RUBYCONF Porto.

Install it via rubygems:

```Bash
gem install reek
```

and run it like this:

```Bash
reek [options] [dir_or_source_file]*
```

## Example

Imagine a source file `demo.rb` containing:

```Ruby
class Dirty
  # This method smells of :reek:NestedIterators but ignores them
  def awful(x, y, offset = 0, log = false)
    puts @screen.title
    @screen = widgets.map { |w| w.each { |key| key += 3 * x } }
    puts @screen.contents
  end
end
```

Reek will report the following code smells in this file:

```
$ reek demo.rb
demo.rb -- 8 warnings:
  [1]:Dirty has no descriptive comment (IrresponsibleModule)
  [3]:Dirty#awful has 4 parameters (LongParameterList)
  [3]:Dirty#awful has boolean parameter 'log' (BooleanParameter)
  [3]:Dirty#awful has the parameter name 'x' (UncommunicativeParameterName)
  [5]:Dirty#awful has the variable name 'w' (UncommunicativeVariableName)
  [3]:Dirty#awful has unused parameter 'log' (UnusedParameters)
  [3]:Dirty#awful has unused parameter 'offset' (UnusedParameters)
  [3]:Dirty#awful has unused parameter 'y' (UnusedParameters)
```

## Fixing Smell Warnings

Reek focuses on high-level code smells, so we can't tell you how to fix warnings in
a generic fashion; this is and will always be completely dependent on your domain
language and business logic.

That said, an example might help you get going. Have a look at this sample of a
Ruby on Rails model (be aware that this is truncated, not working code):

```Ruby
class ShoppingCart < ActiveRecord::Base
  has_many :items

  def gross_price
    items.sum { |item| item.net + item.tax }
  end
end

class Item < ActiveRecord::Base
  belongs_to :shopping_cart
end
```

Running `reek` on this file like this:

```
reek app/models/shopping_cart.rb
```

would report:

```
  [5, 5]:ShoppingCart#gross_price refers to item more than self (FeatureEnvy)
```

Fixing this is pretty straightforward. Put the gross price calculation for a single item
where it belongs, which would be the `Item` class:

```Ruby
class ShoppingCart < ActiveRecord::Base
  has_many :items

  def gross_price
    items.sum { |item| item.gross_price }
  end
end

class Item < ActiveRecord::Base
  belongs_to :shopping_cart

  def gross_price
    net + tax
  end
end
```

The [Code Smells](docs/Code-Smells.md) docs may give you further hints - be sure to check out
those first when you have a warning that you don't know how to deal with.

## Sources

There are multiple ways you can have `reek` work on sources, the most common one just being

```Bash
reek lib/
```

If you don't pass any source arguments to `reek` it just takes the current working directory as source.

So

```Bash
reek
```

is the exact same thing as being explicit:

```Bash
reek .
```

Additionally you can pipe code to `reek` like this:

```Bash
echo "class C; def m; end; end" | reek
```

This would print out:

```Bash
$stdin -- 3 warnings:
  [1]:C has no descriptive comment (IrresponsibleModule)
  [1]:C has the name 'C' (UncommunicativeModuleName)
  [1]:C#m has the name 'm' (UncommunicativeMethodName)
```

## Code smells

Reek currently includes checks for some aspects of
[Control Couple](docs/Control-Couple.md),
[Data Clump](docs/Data-Clump.md),
[Feature Envy](docs/Feature-Envy.md),
[Large Class](docs/Large-Class.md),
[Long Parameter List](docs/Long-Parameter-List.md),
[Simulated Polymorphism](docs/Simulated-Polymorphism.md),
[Too Many Statements](docs/Too-Many-Statements.md),
[Uncommunicative Name](docs/Uncommunicative-Name.md),
[Unused Parameters](docs/Unused-Parameters.md)
and more. See the [Code Smells](docs/Code-Smells.md)
for up to date details of exactly what Reek will check in your code.

Note that [Unused Private Method](docs/Unused-Private-Method.md) is disabled by default
because it is [kind of controversial](https://github.com/troessner/reek/issues/844) which means
you have to explicitly activate in your configuration via

```Yaml
UnusedPrivateMethod:
  enabled: true
```

## Configuration

### Command-line interface

For a basic overview, run

```Ruby
reek --help
```

For a summary of those CLI options see [Command-Line Options](docs/Command-Line-Options.md).

### Configuration file

#### Configuration loading

Configuring Reek via a configuration file is by far the most powerful way.

There are three ways of passing `reek` a configuration file:

1. Using the CLI `-c` switch (see [_Command-line interface_](#command-line-interface) above)
2. Having a file ending with `.reek` either in your current working directory or in a parent directory (more on that later)
3. Having a file ending with `.reek` in your home directory

The order in which Reek tries to find such a configuration
file is exactly the above: first it checks if we have given
it a configuration file explicitly via CLI; then it checks
the current working directory for a file and if it can't
find one, it traverses up the directories until it hits the
root directory; lastly, it checks your home directory.

As soon as Reek detects a configuration file it stops searching
immediately, meaning that from Reek's point of view there exists
exactly one configuration file and one configuration, regardless
of how many `*.reek` files you might have on your filesystem.

#### Configuration options

We put a lot of effort into making Reek's configuration as self explanatory as possible so the
best way to understand it is by looking at a simple
example (e.g. `config.reek` in your project directory):

```yaml
---

### Generic smell configuration

# You can disable smells completely
IrresponsibleModule:
  enabled: false

# You can use filters to silence Reek warnings.
# Either because you simply disagree with Reek (we are not the police) or
# because you want to fix this at a later point in time.
NestedIterators:
  exclude:
    - "MyWorker#self.class_method" # should be refactored
    - "AnotherWorker#instance_method" # should be refactored as well

# A lot of smells allow fine tuning their configuration. You can look up all available options
# in the corresponding smell documentation in /docs. In most cases you probably can just go
# with the defaults as documented in defaults.reek.
DataClump:
  max_copies: 3
  min_clump_size: 3

### Directory specific configuration

# You can configure smells on a per-directory base.
# E.g. the classic Rails case: controllers smell of NestedIterators (see /docs/Nested-Iterators.md) and
# helpers smell of UtilityFunction (see docs/Utility-Function.md)
"web_app/app/controllers":
  NestedIterators:
    enabled: false
"web_app/app/helpers":
  UtilityFunction:
    enabled: false

### Excluding directories

# Directories below will not be scanned at all
exclude_paths:
  - lib/legacy
  - lib/rake/legacy_tasks
```

If you have a directory directive for which a default directive exists, the more specific
one (which is the directory directive) will take precedence.

This configuration for instance:

```yaml
---
IrresponsibleModule:
  enabled: false

TooManyStatements:
  max_statements: 5

"app/controllers":
  TooManyStatements:
    max_statements: 10
```

translates to:

* IrresponsibleModule is disabled everywhere
* TooManyStatements#max_statements is 10 in "app/controllers"
* TooManyStatements#max_statements is 5 everywhere else

For more details please check out the [Basic Smell Options](docs/Basic-Smell-Options.md)
which are supported by every smell type. As you can see above, certain smell
types offer a configuration that goes beyond that of the basic smell options, for instance
[Data Clump](docs/Data-Clump.md).
All options that go beyond the [Basic Smell Options](docs/Basic-Smell-Options.md)
are documented in the corresponding smell type /docs page (if you want to get a quick overview over all possible
configurations you can also check out [the `default.reek` file in this repository](defaults.reek).

Note that you do not need a configuration file at all.
If you're fine with all the [defaults](defaults.reek) we set you can skip this completely.

### Source code comments

In case you need to suppress a smell warning and you can't or don't want to
use configuration files for whatever reasons you can also use special
source code comments like this:

```Ruby
# This method smells of :reek:NestedIterators
def smelly_method foo
  foo.each {|bar| bar.each {|baz| baz.qux}}
end
```

You can even pass in smell specific configuration settings:

```Ruby
# :reek:NestedIterators: { max_allowed_nesting: 2 }
def smelly_method foo
  foo.each {|bar| bar.each {|baz| baz.qux}}
end
```

This is an incredible powerful feature and further explained under [Smell Suppresion](docs/Smell-Suppression.md).

## Usage

Besides the obvious

```Bash
reek [options] [dir_or_source_file]*
```

there are quite a few other ways how to use Reek in your projects:

* Use Reek's [Rake task](docs/Rake-Task.md) to automate detecting code smells
* Add Reek's custom matcher to your [RSpec examples](docs/RSpec-matchers.md)
* Include Reek using the [Developer API](docs/API.md)

## Developing Reek / Contributing

The first thing you want to do after checking out the source code is to run Bundler:

```
bundle install
```

and then run the tests:

```bash
bundle exec rspec spec/your/file_spec.rb            # Runs all tests in spec/your/file_spec.rb
bundle exec rspec spec/your/file_spec.rb:23         # Runs test in line 23
bundle exec cucumber features/your_file.feature     # Runs all scenarios in your_file.feature
bundle exec cucumber features/your_file.feature:23  # Runs scenario at line 23
```

Or just run the whole test suite:

```
bundle exec rake
```

From then on you should check out:
* [How Reek works internally](docs/How-reek-works-internally.md)
* [the contributing guide](CONTRIBUTING.md)


If you don't feel like getting your hands dirty with code there are still other ways you can help us:

* Open up an [issue](https://github.com/troessner/reek/issues) and report bugs
* Suggest other improvements like additional smells for instance

## Output formats

`reek` supports 5 output formats:

* plain text (default)
* HTML (`--format html`)
* YAML (`--format yaml`, see also [YAML Reports](docs/YAML-Reports.md))
* JSON (`--format json`)
* XML  (`--format xml`)

## Working with Rails

Making Reek "Rails"-friendly is fairly simple since we support directory specific configurations (`directory directives` in Reek talk).
Just add this to your configuration file:

```Yaml
"app/controllers":
  IrresponsibleModule:
    enabled: false
  NestedIterators:
    max_allowed_nesting: 2
  UnusedPrivateMethod:
    enabled: false
"app/helpers":
  IrresponsibleModule:
    enabled: false
  UtilityFunction:
    enabled: false
```

Be careful though, Reek does not merge your configuration entries, so if you already have a directory directive for "app/controllers" or "app/helpers" you need to update those directives instead of copying the above YAML sample into your configuration file.

## Integrations

### Editor integrations

* [Vim plugin](https://github.com/rainerborene/vim-reek)
* [TextMate Bundle](https://github.com/peeyush1234/reek.tmbundle)
* [Atom plugin](https://atom.io/packages/linter-reek)
* [SublimeLinter plugin](https://packagecontrol.io/packages/SublimeLinter-contrib-reek)

### Projects that use or support us

* [overcommit](https://github.com/brigade/overcommit) - a Git commit hook manager with support for
  Reek
* [ruby-critic](https://github.com/whitesmith/rubycritic) - gem that wraps around static analysis gems such as `reek`, [flay](https://github.com/seattlerb/flay) and [flog](https://github.com/seattlerb/flog)
* [pronto-reek](https://github.com/mmozuras/pronto-reek) - Reek integration for [pronto](https://github.com/mmozuras/pronto)

### Misc

* [Colorful output for `reek`](https://github.com/joenas/preek)
  (also with [Guard::Preek](https://github.com/joenas/guard-preek))

## Brothers and sisters

A non-exhaustive list of other static code analyzers you might want to look into:

* [debride](https://github.com/seattlerb/debride) - analyze code for potentially uncalled / dead methods
* [flay](https://github.com/seattlerb/flay) - analyze code for structural similarities
* [flog](https://github.com/seattlerb/flog) - reports the most tortured code in an easy to read pain
report
* [SandiMeter](https://github.com/makaroni4/sandi_meter) - checking your Ruby code for Sandi Metz' four rules
* [ruby-lint](https://github.com/YorickPeterse/ruby-lint) - static code analysis tool
* [Fasterer](https://github.com/DamirSvrtan/fasterer) - Fasterer will suggest some speed improvements based on [fast-ruby](https://github.com/JuanitoFatas/fast-ruby)

## Contributors

The Reek core team consists of:

* [Matijs van Zuijlen](https://github.com/mvz)
* [Piotr Szotkowski](https://github.com/chastell)
* [Timo Rößner](https://github.com/troessner)

The original author of Reek is [Kevin Rutherford](https://github.com/kevinrutherford).

The author of Reek’s logo is [Sonja Heinen](http://yippee.io).

Notable contributions came from:

* [Andrew Wagner](https://github.com/arwagner)
* [Gilles Leblanc](https://github.com/gilles-leblanc)
* [Emil Rehnberg](https://github.com/EmilRehnberg)

## Additional resources

### Miscellaneous

* [Reek Driven Development](docs/Reek-Driven-Development.md)
* [Versioning policy](docs/Versioning-Policy.md)

### More information

* [Stack Overflow](https://stackoverflow.com/questions/tagged/reek)
* [RubyDoc.info](http://www.rubydoc.info/gems/reek)