anchor.diff:      logical(c_bool), intent(inout) :: success
   
       call test_cross_product(success)
  +    call test_bbox(success)
       call test_vector_close(success)
       call test_in_interval(success)
   
  
positive.code: 
    end subroutine test_cross_product
  
    subroutine test_vector_close(success)
      logical(c_bool), intent(inout) :: success
      ! Variables outside of signature.
  
negative.code: module test_helpers
  
    use iso_c_binding, only: c_double, c_bool
    use helpers, only: cross_product, bbox, vector_close, in_interval
    use types, only: dp
    implicit none
    private test_cross_product, test_vector_close, test_in_interval
  