Method: RSpec::Core::Hooks#before

Defined in:
lib/rspec/core/hooks.rb

#before(&block) ⇒ void #before(scope, &block) ⇒ void #before(scope, conditions, &block) ⇒ void #before(conditions, &block) ⇒ void Also known as: append_before

Note:

The :example and :context scopes are also available as :each and :all, respectively. Use whichever you prefer.

Note:

The :suite scope is only supported for hooks registered on RSpec.configuration since they exist independently of any example or example group.

Declare a block of code to be run before each example (using :example) or once before any example (using :context). These are usually declared directly in the ExampleGroup to which they apply, but they can also be shared across multiple groups.

You can also use before(:suite) to run a block of code before any example groups are run. This should be declared in RSpec.configure.

Instance variables declared in before(:example) or before(:context) are accessible within each example.

Order

before hooks are stored in three scopes, which are run in order: :suite, :context, and :example. They can also be declared in several different places: RSpec.configure, a parent group, the current group. They are run in the following order:

before(:suite)    # Declared in RSpec.configure.
before(:context)  # Declared in RSpec.configure.
before(:context)  # Declared in a parent group.
before(:context)  # Declared in the current group.
before(:example)  # Declared in RSpec.configure.
before(:example)  # Declared in a parent group.
before(:example)  # Declared in the current group.

If more than one before is declared within any one scope, they are run in the order in which they are declared.

Conditions

When you add a conditions hash to before(:example) or before(:context), RSpec will only apply that hook to groups or examples that match the conditions. e.g.

RSpec.configure do |config|
  config.before(:example, :authorized => true) do
     :authorized_user
  end
end

describe Something, :authorized => true do
  # The before hook will run in before each example in this group.
end

describe SomethingElse do
  it "does something", :authorized => true do
    # The before hook will run before this example.
  end

  it "does something else" do
    # The hook will not run before this example.
  end
end

Note that filtered config :context hooks can still be applied to individual examples that have matching metadata. Just like Ruby's object model is that every object has a singleton class which has only a single instance, RSpec's model is that every example has a singleton example group containing just the one example.

Warning: before(:suite, :with => :conditions)

The conditions hash is used to match against specific examples. Since before(:suite) is not run in relation to any specific example or group, conditions passed along with :suite are effectively ignored.

Exceptions

When an exception is raised in a before block, RSpec skips any subsequent before blocks and the example, but runs all of the after(:example) and after(:context) hooks.

Warning: implicit before blocks

before hooks can also be declared in shared contexts which get included implicitly either by you or by extension libraries. Since RSpec runs these in the order in which they are declared within each scope, load order matters, and can lead to confusing results when one before block depends on state that is prepared in another before block that gets run later.

Warning: before(:context)

It is very tempting to use before(:context) to speed things up, but we recommend that you avoid this as there are a number of gotchas, as well as things that simply don't work.

Context

before(:context) is run in an example that is generated to provide group context for the block.

Instance variables

Instance variables declared in before(:context) are shared across all the examples in the group. This means that each example can change the state of a shared object, resulting in an ordering dependency that can make it difficult to reason about failures.

Unsupported RSpec constructs

RSpec has several constructs that reset state between each example automatically. These are not intended for use from within before(:context):

  • let declarations
  • subject declarations
  • Any mocking, stubbing or test double declaration

other frameworks

Mock object frameworks and database transaction managers (like ActiveRecord) are typically designed around the idea of setting up before an example, running that one example, and then tearing down. This means that mocks and stubs can (sometimes) be declared in before(:context), but get torn down before the first real example is ever run.

You can create database-backed model objects in a before(:context) in rspec-rails, but it will not be wrapped in a transaction for you, so you are on your own to clean up in an after(:context) block.

Examples:

before(:example) declared in an ExampleGroup


describe Thing do
  before(:example) do
    @thing = Thing.new
  end

  it "does something" do
    # Here you can access @thing.
  end
end

before(:context) declared in an ExampleGroup


describe Parser do
  before(:context) do
    File.open(file_to_parse, 'w') do |f|
      f.write <<-CONTENT
        stuff in the file
      CONTENT
    end
  end

  it "parses the file" do
    Parser.parse(file_to_parse)
  end

  after(:context) do
    File.delete(file_to_parse)
  end
end

Overloads:

  • #before(scope, &block) ⇒ void

    Parameters:

    • scope (Symbol)

      :example, :context, or :suite (defaults to :example)

  • #before(scope, conditions, &block) ⇒ void

    Parameters:

    • scope (Symbol)

      :example, :context, or :suite (defaults to :example)

    • conditions (Hash)

      constrains this hook to examples matching these conditions e.g. before(:example, :ui => true) { ... } will only run with examples or groups declared with :ui => true.

  • #before(conditions, &block) ⇒ void

    Parameters:

    • conditions (Hash)

      constrains this hook to examples matching these conditions e.g. before(:example, :ui => true) { ... } will only run with examples or groups declared with :ui => true.

See Also:



197
198
199
# File 'lib/rspec/core/hooks.rb', line 197

def before(*args, &block)
  hooks.register :append, :before, *args, &block
end