Using shared_context

Use shared_context to define a block that will be evaluated in the context of example groups either locally, using include_context in an example group, or globally using config.include_context.

When implicitly including shared contexts via matching metadata, the normal way is to define matching metadata on an example group, in which case the context is included in the entire group. However, you also have the option to include it in an individual example instead. RSpec treats every example as having a singleton example group (analogous to Ruby's singleton classes) containing just the one example.

Background

Given a file named "shared_stuff.rb" with:

RSpec.configure do |rspec|
  # This config option will be enabled by default on RSpec 4,
  # but for reasons of backwards compatibility, you have to
  # set it on RSpec 3.
  #
  # It causes the host group and examples to inherit metadata
  # from the shared context.
  rspec.shared_context_metadata_behavior = :apply_to_host_groups
end

RSpec.shared_context "shared stuff", :shared_context => :metadata do
  before { @some_var = :some_value }
  def shared_method
    "it works"
  end
  let(:shared_let) { {'arbitrary' => 'object'} }
  subject do
    'this is the subject'
  end
end

RSpec.configure do |rspec|
  rspec.include_context "shared stuff", :include_shared => true
end

Declare a shared context and include it with include_context

Given a file named "shared_context_example.rb" with:

require "./shared_stuff.rb"

RSpec.describe "group that includes a shared context using 'include_context'" do
  include_context "shared stuff"

  it "has access to methods defined in shared context" do
    expect(shared_method).to eq("it works")
  end

  it "has access to methods defined with let in shared context" do
    expect(shared_let['arbitrary']).to eq('object')
  end

  it "runs the before hooks defined in the shared context" do
    expect(@some_var).to be(:some_value)
  end

  it "accesses the subject defined in the shared context" do
    expect(subject).to eq('this is the subject')
  end

  group = self

  it "inherits metadata from the included context" do |ex|
    expect(group.metadata).to include(:shared_context => :metadata)
    expect(ex.metadata).to include(:shared_context => :metadata)
  end
end

When I run rspec shared_context_example.rb

Then the examples should all pass.

Declare a shared context, include it with include_context and extend it with an additional block

Given a file named "shared_context_example.rb" with:

require "./shared_stuff.rb"

RSpec.describe "including shared context using 'include_context' and a block" do
  include_context "shared stuff" do
    let(:shared_let) { {'in_a' => 'block'} }
  end

  it "evaluates the block in the shared context" do
    expect(shared_let['in_a']).to eq('block')
  end
end

When I run rspec shared_context_example.rb

Then the examples should all pass.

Declare a shared context and include it with metadata

Given a file named "shared_context_example.rb" with:

require "./shared_stuff.rb"

RSpec.describe "group that includes a shared context using metadata", :include_shared => true do
  it "has access to methods defined in shared context" do
    expect(shared_method).to eq("it works")
  end

  it "has access to methods defined with let in shared context" do
    expect(shared_let['arbitrary']).to eq('object')
  end

  it "runs the before hooks defined in the shared context" do
    expect(@some_var).to be(:some_value)
  end

  it "accesses the subject defined in the shared context" do
    expect(subject).to eq('this is the subject')
  end

  group = self

  it "inherits metadata from the included context" do |ex|
    expect(group.metadata).to include(:shared_context => :metadata)
    expect(ex.metadata).to include(:shared_context => :metadata)
  end
end

When I run rspec shared_context_example.rb

Then the examples should all pass.

Declare a shared context and include it with metadata of an individual example

Given a file named "shared_context_example.rb" with:

require "./shared_stuff.rb"

RSpec.describe "group that does not include the shared context" do
  it "does not have access to shared methods normally" do
    expect(self).not_to respond_to(:shared_method)
  end

  it "has access to shared methods from examples with matching metadata", :include_shared => true do
    expect(shared_method).to eq("it works")
  end

  it "inherits metadata from the included context due to the matching metadata", :include_shared => true do |ex|
    expect(ex.metadata).to include(:shared_context => :metadata)
  end
end

When I run rspec shared_context_example.rb

Then the examples should all pass.