Module: RSpec::Core::Hooks

Included in:
Configuration, ExampleGroup
Defined in:
lib/rspec/core/hooks.rb

Overview

Provides before, after and around hooks as a means of supporting common setup and teardown. This module is extended onto ExampleGroup, making the methods available from any describe or context block and included in Configuration, making them available off of the configuration object to define global setup or teardown logic.

Instance Method Summary collapse

Instance Method Details

#after(&block) ⇒ void #after(scope, &block) ⇒ void #after(scope, conditions, &block) ⇒ void #after(conditions, &block) ⇒ void Also known as: prepend_after

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 after each example (using :example) or once after all examples n the context (using :context). See #before for more information about ordering.

Exceptions

after hooks are guaranteed to run even when there are exceptions in before hooks or examples. When an exception is raised in an after block, the exception is captured for later reporting, and subsequent after blocks are run.

Order

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

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

This is the reverse of the order in which before hooks are run. Similarly, if more than one after is declared within any one scope, they are run in reverse order of that in which they are declared. Also around hooks will all have run before any after hooks are invoked.

Overloads:

  • #after(scope, &block) ⇒ void

    Parameters:

    • scope (Symbol) —

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

  • #after(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. after(:example, :ui => true) { ... } will only run with examples or groups declared with :ui => true.

  • #after(conditions, &block) ⇒ void

    Parameters:

    • conditions (Hash) —

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

See Also:

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# File 'lib/rspec/core/hooks.rb', line 273
def after(*args, &block)
  hooks.register :prepend, :after, *args, &block
end

#append_after(*args, &block) ⇒ void

Adds block to the back of the list of after blocks in the same scope (:example, :context, or :suite).

See #after for scoping semantics.

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# File 'lib/rspec/core/hooks.rb', line 283
def append_after(*args, &block)
  hooks.register :append, :after, *args, &block
end

#around(&block) ⇒ void #around(scope, &block) ⇒ void #around(scope, conditions, &block) ⇒ void #around(conditions, &block) ⇒ void

Note:

the syntax of around is similar to that of before and after but the semantics are quite different. before and after hooks are run in the context of of the examples with which they are associated, whereas around hooks are actually responsible for running the examples. Consequently, around hooks do not have direct access to resources that are made available within the examples and their associated before and after hooks.

Note:

:example/:each is the only supported scope.

Declare a block of code, parts of which will be run before and parts after the example. It is your responsibility to run the example:

around(:example) do |ex|
  # Do some stuff before.
  ex.run
  # Do some stuff after.
end

The yielded example aliases run with call, which lets you treat it like a Proc. This is especially handy when working with libraries that manage their own setup and teardown using a block or proc syntax, e.g.

around(:example) {|ex| Database.transaction(&ex)}
around(:example) {|ex| FakeFS(&ex)}

Order

All around hooks execute immediately surrounding an example, this means that all before hooks will have run and no after hooks will have run yet.

They are not a synonym for before/after.

Overloads:

  • #around(scope, &block) ⇒ void

    Parameters:

    • scope (Symbol) —

      :example (defaults to :example) present for syntax parity with before and after, but :example/:each is the only supported value.

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

    Parameters:

    • scope (Symbol) —

      :example (defaults to :example) present for syntax parity with before and after, but :example/:each is the only supported value.

    • conditions (Hash) —

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

  • #around(conditions, &block) ⇒ void

    Parameters:

    • conditions (Hash) —

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

Yields:

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# File 'lib/rspec/core/hooks.rb', line 340
def around(*args, &block)
  hooks.register :prepend, :around, *args, &block
end

#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. Any around hooks will execute later than any before hook regardless of scope.

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


RSpec.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


RSpec.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:

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# File 'lib/rspec/core/hooks.rb', line 198
def before(*args, &block)
  hooks.register :append, :before, *args, &block
end

#prepend_before(*args, &block) ⇒ void

Adds block to the front of the list of before blocks in the same scope (:example, :context, or :suite).

See #before for scoping semantics.

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# File 'lib/rspec/core/hooks.rb', line 208
def prepend_before(*args, &block)
  hooks.register :prepend, :before, *args, &block
end