Usage plan of Givens Testing Library: More RSpec-like testing library in Haskell.

givens-sample.hs

describe "example group" $ do
  -- Equivalent with RSpec's `let!(:hoge){ 1 }`.
  -- An action passed to `given` function is executed every time
  -- an example (defined by `it`) in the `describe` block is executed,
  -- then the action's result is cached until the example's execution completes.
  hoge <- given $ return 1

  -- Equivalent with RSpec's `let(:hoge){ 1 }` (without exclamation).
  hogeIfNecessary <- givenIfNecessary $ runOnlyIfReferred

  -- To get the value of `given`, use `refer`.
  foo <- given ((+ 1) <$> refer hoge)

  -- Same as RSpec's `before(:each)`
  before $
    putStrLn =<< refer foo

  it "an example" $ do
    refer hoge `shouldReturn` 1

  it "another example" $ do
    refer foo `shouldReturn` 2