chervil/spec/core_spec.rb

module Chervil
  RSpec.describe Core do
    it 'does arithmetic' do
      expect(Core::CORE['+'].call([1.0, 2.0])).to eq(3.0)
      expect(Core::CORE['-'].call([3.0, 1.0])).to eq(2.0)
      expect(Core::CORE['*'].call([2.0, 3.0])).to eq(6.0)
      expect(Core::CORE['/'].call([6.0, 2.0])).to eq(3.0)
    end

    it 'compares values' do
      expect(Core::CORE['='].call([1.0, 2.0])).to eq(false)
      expect(Core::CORE['='].call([1.0, 1.0])).to eq(true)
      expect(Core::CORE['<'].call([2.0, 1.0])).to eq(false)
      expect(Core::CORE['<'].call([2.0, 3.0])).to eq(true)
      expect(Core::CORE['>'].call([2.0, 1.0])).to eq(true)
      expect(Core::CORE['>'].call([2.0, 3.0])).to eq(false)
      expect(Core::CORE['<='].call([2.0, 1.0])).to eq(false)
      expect(Core::CORE['<='].call([2.0, 2.0])).to eq(true)
      expect(Core::CORE['>='].call([2.0, 2.0])).to eq(true)
      expect(Core::CORE['>='].call([2.0, 3.0])).to eq(false)
      expect(Core::CORE['and'].call([2.0, 3.0])).to eq(true)
      expect(Core::CORE['and'].call([2.0, 3.0, false])).to eq(false)
      expect(Core::CORE['or'].call([2.0, 3.0, false])).to eq(true)
      expect(Core::CORE['or'].call([false, false])).to eq(false)
      expect(Core::CORE['not'].call([1.0])).to eq(false)
      expect(Core::CORE['not'].call([false])).to eq(true)
    end

    it 'returns an error if argument has the wrong type' do
      expect(Core::CORE['+'].call([1.0, "hello"])).to eq(
        Error.new("Expected an argument of type number but got string")
      )
    end

    it 'returns an error if given the wrong number of arguments' do
      expect(Core::CORE['not'].call([1.0, 2.0])).to eq(
        Error.new("Expected 1 argument but received 2")
      )
    end

    it 'can do car and cdr' do
      expect(Core::CORE['car'].call([[1, 2, 3]])).to eq(1)
      expect(Core::CORE['cdr'].call([[1, 2, 3]])).to eq([2, 3])
      expect(Core::CORE['car'].call([1.0])).to eq(
        Error.new("Expected an argument of type list but got number")
      )
      expect(Core::CORE['cdr'].call([1.0])).to eq(
        Error.new("Expected an argument of type list but got number")
      )
      expect(Core::CORE['car'].call([[1, 2, 3], [4, 5, 6]])).to eq(
        Error.new("Expected 1 argument but received 2")
      )
      expect(Core::CORE['cdr'].call([[1, 2, 3], [4, 5, 6]])).to eq(
        Error.new("Expected 1 argument but received 2")
      )
      expect(Core::CORE['car'].call([Array.new])).to eq(
        Error.new("`car` expects a non-empty list")
      )
    end

    it 'implements cons' do
      expect(Core::CORE['cons'].call([1.0, [2.0, 3.0]])).to eq(
        [1.0, 2.0, 3.0]
      )
    end

    it 'implements map' do
      env = Env.new
      Core.eval("(define (plus-one x) (+ x 1))", env)
      expect(Core.eval("(map plus-one '(1 2 3))", env)).to eq(
        [2.0, 3.0, 4.0]
      )
    end
  end
end