PragmaticGP_pile3.feature

Feature: Pile return values
  In order to interpret a Pile script as a function of x
  As a symbolic regression modeler
  I want a scalar value to be returned from any executed script

  Scenario: return value is the top stack item after execution
    Given the Pile script "1.2 3.4 +"
    When I execute it with x = 1
    Then the returned value should be 4.6

  Scenario: returning a value does NOT pop it from the stack
    Given the Pile script "1.2 3.4 + 5.6 7.8 +"
    When I execute it with x = 1
    Then the returned value should be 13.4
    And the stack should contain 2 items

  Scenario: return 1000000000.0 if the stack is empty
    Given the Pile script "* / + -"
    When I execute it with x = 9.1
    Then the returned value should be 1000000000.0