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random programming notes

User-defined Metadata in Rspec

Rspec describe, context and it supports metadata in the form of a hash. Syntax as follow:

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RSpec.describe "some description", :foo => 1, :bar do

  context "when some condition", :value => true do
  
      it "does something", :hihi, :day => 10 do |example|
          expect(exapmle.metadata[:foo]).to eq(1)
          expect(example.metadata[:value]).to be true
          expect(example.metadata[:hihi]).to be true
          expect(example.metadata[:day]).to eq(10)
      end
  
  end
  
end

There are 2 ways that I use metadata in RSpec.

To include shared_examples / shared_context

RSpec includes shared_context and shared_examples with same metadata

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RSpec.shared_context "shared stuff", :a => :b do
  def shared_method
      pp "hello"
  end
end

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Rspec.describe "use shared stuff", :a => :b do
end

is equivalent to

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Rspec.describe "use shared stuff" do
  include_context "shared_stuff"
end

Use metadata as variables

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RSpec.describe "use metadata as var", :num_elements => 7 do

  let(:elements) do |example|
      (1..example.metadata[:num_elements]).map { |n| "element#{n}" }
  end
  
  it "prints elements" do
      pp elements
  end

end