Current progress

koans/about_strings.rb

@@ -0,0 +1,197 @@
+require File.expand_path(File.dirname(__FILE__) + '/neo')
+
+class AboutStrings < Neo::Koan
+  def test_double_quoted_strings_are_strings
+    string = "Hello, World"
+    assert_equal true, string.is_a?(String)
+  end
+
+  def test_single_quoted_strings_are_also_strings
+    string = 'Goodbye, World'
+    assert_equal true, string.is_a?(String)
+  end
+
+  def test_use_single_quotes_to_create_string_with_double_quotes
+    string = 'He said, "Go Away."'
+    assert_equal "He said, \"Go Away.\"", string
+  end
+
+  def test_use_double_quotes_to_create_strings_with_single_quotes
+    string = "Don't"
+    assert_equal "Don't", string
+  end
+
+  def test_use_backslash_for_those_hard_cases
+    a = "He said, \"Don't\""
+    b = 'He said, "Don\'t"'
+    assert_equal true, a == b
+  end
+
+  def test_use_flexible_quoting_to_handle_really_hard_cases
+    a = %(flexible quotes can handle both ' and " characters)
+    b = %!flexible quotes can handle both ' and " characters!
+    c = %{flexible quotes can handle both ' and " characters}
+    assert_equal true, a == b
+    assert_equal true, a == c
+  end
+
+  def test_flexible_quotes_can_handle_multiple_lines
+    long_string = %{
+It was the best of times,
+It was the worst of times.
+}
+    assert_equal 54, long_string.length
+    assert_equal 3, long_string.lines.count
+    assert_equal "\n", long_string[0,1]
+  end
+
+  def test_here_documents_can_also_handle_multiple_lines
+    long_string = <<EOS
+It was the best of times,
+It was the worst of times.
+EOS
+    assert_equal 53, long_string.length
+    assert_equal 2, long_string.lines.count
+    assert_equal "I", long_string[0,1]
+  end
+
+  def test_plus_will_concatenate_two_strings
+    string = "Hello, " + "World"
+    assert_equal "Hello, World", string
+  end
+
+  def test_plus_concatenation_will_leave_the_original_strings_unmodified
+    hi = "Hello, "
+    there = "World"
+    string = hi + there
+    assert_equal "Hello, ", hi
+    assert_equal "World", there
+  end
+
+  def test_plus_equals_will_concatenate_to_the_end_of_a_string
+    hi = "Hello, "
+    there = "World"
+    hi += there
+    assert_equal "Hello, World", hi
+  end
+
+  def test_plus_equals_also_will_leave_the_original_string_unmodified
+    original_string = "Hello, "
+    hi = original_string
+    there = "World"
+    hi += there
+    assert_equal "Hello, ", original_string
+  end
+
+  def test_the_shovel_operator_will_also_append_content_to_a_string
+    hi = "Hello, "
+    there = "World"
+    hi << there
+    assert_equal "Hello, World", hi
+    assert_equal "World", there
+  end
+
+  def test_the_shovel_operator_modifies_the_original_string
+    original_string = "Hello, "
+    hi = original_string
+    there = "World"
+    hi << there
+    assert_equal "Hello, World", original_string
+
+    # THINK ABOUT IT:
+    #
+    # Ruby programmers tend to favor the shovel operator (<<) over the
+    # plus equals operator (+=) when building up strings.  Why?
+  end
+
+  def test_double_quoted_string_interpret_escape_characters
+    string = "\n"
+    assert_equal 1, string.size
+  end
+
+  def test_single_quoted_string_do_not_interpret_escape_characters
+    string = '\n'
+    assert_equal 2, string.size
+  end
+
+  def test_single_quotes_sometimes_interpret_escape_characters
+    string = '\\\''
+    assert_equal 2, string.size
+    assert_equal "\\'", string
+  end
+
+  def test_double_quoted_strings_interpolate_variables
+    value = 123
+    string = "The value is #{value}"
+    assert_equal "The value is 123", string
+  end
+
+  def test_single_quoted_strings_do_not_interpolate
+    value = 123
+    string = 'The value is #{value}'
+    assert_equal 'The value is #{value}', string
+  end
+
+  def test_any_ruby_expression_may_be_interpolated
+    string = "The square root of 5 is #{Math.sqrt(5)}"
+    assert_equal "The square root of 5 is " + Math.sqrt(5).to_s, string
+  end
+
+  def test_you_can_get_a_substring_from_a_string
+    string = "Bacon, lettuce and tomato"
+    assert_equal "let", string[7,3]
+    assert_equal "let", string[7..9]
+  end
+
+  def test_you_can_get_a_single_character_from_a_string
+    string = "Bacon, lettuce and tomato"
+    assert_equal 'a', string[1]
+
+    # Surprised?
+  end
+
+  in_ruby_version("1.8") do
+    def test_in_older_ruby_single_characters_are_represented_by_integers
+      assert_equal __, ?a
+      assert_equal __, ?a == 97
+
+      assert_equal __, ?b == (?a + 1)
+    end
+  end
+
+  in_ruby_version("1.9", "2", "3") do
+    def test_in_modern_ruby_single_characters_are_represented_by_strings
+      assert_equal "a", ?a
+      assert_equal false, ?a == 97
+    end
+  end
+
+  def test_strings_can_be_split
+    string = "Sausage Egg Cheese"
+    words = string.split
+    assert_equal ["Sausage", "Egg", "Cheese"], words
+  end
+
+  def test_strings_can_be_split_with_different_patterns
+    string = "the:rain:in:spain"
+    words = string.split(/:/)
+    assert_equal ["the", "rain", "in", "spain"], words
+
+    # NOTE: Patterns are formed from Regular Expressions.  Ruby has a
+    # very powerful Regular Expression library.  We will become
+    # enlightened about them soon.
+  end
+
+  def test_strings_can_be_joined
+    words = ["Now", "is", "the", "time"]
+    assert_equal "Now is the time", words.join(" ")
+  end
+
+  def test_strings_are_unique_objects
+    a = "a string"
+    b = "a string"
+
+    assert_equal true, a           == b
+    assert_equal false, a.object_id == b.object_id
+  end
+end