chervil/spec/lexer_spec.rb

module Chervil
  RSpec.describe Lexer do
    it 'lexes parens' do
      expect(Lexer.new('()').tokenize).to eq(
        [
          Token.new(:lparen, '('),
          Token.new(:rparen, ')'),
          Token.new(:eof, 'eof')
        ]
      )
    end

    it 'lexes integers' do
      expect(Lexer.new('1').get_next_token).to eq(Token.new(:number, '1'))
    end

    it 'lexes floats' do
      expect(Lexer.new('2.3').get_next_token).to eq(Token.new(:number, '2.3'))
    end

    it 'ignores whitespace' do
      expect(Lexer.new('1 2 3').tokenize).to eq(
        [
          Token.new(:number, '1'),
          Token.new(:number, '2'),
          Token.new(:number, '3'),
          Token.new(:eof, 'eof')
        ]
      )
    end

    it 'lexes identifiers' do
      expect(Lexer.new('hello').get_next_token).to eq(
        Token.new(:identifier, 'hello')
      )
    end

    it 'lexes strings' do
      expect(Lexer.new('"hello"').get_next_token).to eq(
        Token.new(:string, 'hello')
      )
    end

    it 'lexes booleans' do
      lexer = Lexer.new('#t #f')
      expect(lexer.get_next_token).to eq(Token.new(:boolean, true))
      expect(lexer.get_next_token).to eq(Token.new(:boolean, false))
    end

    it 'returns an error given an unterminated string' do
      lexer = Lexer.new('"hello world')
      expect(lexer.get_next_token).to eq(Error.new("Unterminated string"))
    end

    it 'lexes quotes' do
      lexer = Lexer.new('\'')
      expect(lexer.get_next_token).to eq(Token.new(:quote, '\''))
    end
  end
end