Running Rspec tests multiple times with different configuration

Readme.md

Doing refactoring it is nice to run a bunch of tests for the legacy code and a new one. We can duplicate Rspec test cases by copy-pase or we can re-run the same tests providing a variable with different values, for example base_path for requests.

foo_spec.rb

# spec/examples/multiple/foo_spec.rb

# This is an actual test
require "spec_helper"

describe "Foo" do
  it "has one of available values" do
    expect(variable).to be_in([:foo, :bar, :baz])
  end
end

multiple_run_helper.rb

# spec/support/multiple_run_helper.rb

# This module duplicates examples which have :multiple_run in the metadata

module MultipleRunHelper
  VARIABLE_VALUES = [:foo, :bar, :baz]

  RSpec.shared_context "Multiple Run variable" do
    let(:variable) { |example| example.metadata[:variable] }
  end

  RSpec.configure do |config|
    config.on_example_group_definition do |group|
      if group.metadata[:multiple_run]
        group.descendants.each do |desc_group|
          desc_group.examples.clone.each do |example|
            # clone example for every variable
            VARIABLE_VALUES.each { |variable| example.duplicate_with(variable: variable) }

            # remove example without variable
            desc_group.remove_example(example)
          end
        end

        # add a common variable
        group.include_context("Multiple Run variable")
      end
    end
  end
end

Output:

$rspec spec/examples/multiple/foo_spec.rb -f d

Randomized with seed 62690

Foo
  has one of available values
  has one of available values
  has one of available values

Finished in 0.03669 seconds
3 examples, 0 failures

spec_helper.rb

# spec/spec_helper.rb

# This adds :multiple_run to metadata for duplicated tests

RSpec.configure do |config|
  config.define_derived_metadata(file_path: %r{/spec/examples/multiple}) do |metadata|
    metadata[:multiple_run] = true
  end

  config.include(MultipleRunHelper, multiple_run: true)
end