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Project: RSpec Core 2.9

Publisher: RSpec

Define helper methods in a module

You can define helper methods in a module and include it in
your example groups using the config.include configuration
option. config.extend can be used to extend the module onto
your example groups so that the methods in the module are available
in the example groups themselves (but not in the actual examples).

You can also include or extend the module onto only certain example
groups by passing a metadata hash as the last argument. Only groups
that match the given metadata will include or extend the module.

If you set the treat_symbols_as_metadata_keys_with_true_values config option
to true, you can specify metadata using only symbols.

Background
Given
a file named "helpers.rb" with: 
module Helpers
  def help
    :available
  end
end
Scenarios
  1. include a module in all example groups
  2. extend a module in all example groups
  3. include a module in only some example groups
  4. extend a module in only some example groups
  5. use symbols as metadata
include a module in all example groups
Given
a file named "include_module_spec.rb" with: 
require './helpers'

RSpec.configure do |c|
  c.include Helpers
end

describe "an example group" do
  it "has access the helper methods defined in the module" do
    help.should be(:available)
  end
end
When
I run rspec include_module_spec.rb
Then
the examples should all pass
extend a module in all example groups
Given
a file named "extend_module_spec.rb" with: 
require './helpers'

RSpec.configure do |c|
  c.extend Helpers
end

describe "an example group" do
  puts "Help is #{help}"

  it "does not have access to the helper methods defined in the module" do
    expect { help }.to raise_error(NameError)
  end
end
When
I run rspec extend_module_spec.rb
Then
the examples should all pass
And
the output should contain "Help is available"
include a module in only some example groups
Given
a file named "include_module_in_some_groups_spec.rb" with: 
require './helpers'

RSpec.configure do |c|
  c.include Helpers, :foo => :bar
end

describe "an example group with matching metadata", :foo => :bar do
  it "has access the helper methods defined in the module" do
    help.should be(:available)
  end
end

describe "an example group without matching metadata" do
  it "does not have access to the helper methods defined in the module" do
    expect { help }.to raise_error(NameError)
  end
end
When
I run rspec include_module_in_some_groups_spec.rb
Then
the examples should all pass
extend a module in only some example groups
Given
a file named "extend_module_in_only_some_groups_spec.rb" with: 
require './helpers'

RSpec.configure do |c|
  c.extend Helpers, :foo => :bar
end

describe "an example group with matching metadata", :foo => :bar do
  puts "In a matching group, help is #{help}"

  it "does not have access to the helper methods defined in the module" do
    expect { help }.to raise_error(NameError)
  end
end

describe "an example group without matching metadata" do
  puts "In a non-matching group, help is #{help rescue 'not available'}"

  it "does not have access to the helper methods defined in the module" do
    expect { help }.to raise_error(NameError)
  end
end
When
I run rspec extend_module_in_only_some_groups_spec.rb
Then
the examples should all pass
And
the output should contain "In a matching group, help is available"
And
the output should contain "In a non-matching group, help is not available"
use symbols as metadata
Given
a file named "symbols_as_metadata_spec.rb" with: 
require './helpers'

RSpec.configure do |c|
  c.treat_symbols_as_metadata_keys_with_true_values = true
  c.include Helpers, :include_helpers
  c.extend  Helpers, :extend_helpers
end

describe "an example group with matching include metadata", :include_helpers do
  puts "In a group not matching the extend filter, help is #{help rescue 'not available'}"

  it "has access the helper methods defined in the module" do
    help.should be(:available)
  end
end

describe "an example group with matching extend metadata", :extend_helpers do
  puts "In a group matching the extend filter, help is #{help}"

  it "does not have access to the helper methods defined in the module" do
    expect { help }.to raise_error(NameError)
  end
end
When
I run rspec symbols_as_metadata_spec.rb
Then
the examples should all pass
And
the output should contain "In a group not matching the extend filter, help is not available"
And
the output should contain "In a group matching the extend filter, help is available"

Last published about 2 years ago by dchelimsky.