Added Koan on basic objects

koans/about_objects.rb

@@ -0,0 +1,56 @@
+require File.expand_path(File.dirname(__FILE__) + '/edgecase')
+
+class AboutObjects < EdgeCase::Koan
+  def test_everything_is_an_object
+    assert_equal __, 1.is_a?(Object)
+    assert_equal __, 1.5.is_a?(Object)
+    assert_equal __, "string".is_a?(Object)
+    assert_equal __, nil.is_a?(Object)
+    assert_equal __, Object.is_a?(Object)
+  end
+
+  def test_objects_can_be_converted_to_strings
+    assert_equal __, 123.to_s
+    assert_equal __, nil.to_s
+  end
+
+  def test_objects_can_be_inspected
+    assert_equal __, 123.inspect
+    assert_equal __, nil.inspect
+  end
+
+  def test_every_object_has_an_id
+    obj = Object.new
+    assert_equal __, obj.object_id.class
+  end
+
+  def test_every_object_has_different_id
+    obj = Object.new
+    another_obj = Object.new
+    assert_equal __, obj.object_id != another_obj.object_id
+  end
+
+  def test_some_system_objects_always_have_the_same_id
+    assert_equal __, false.object_id
+    assert_equal __, true.object_id
+    assert_equal __, nil.object_id
+  end
+
+  def test_small_integers_have_fixed_ids
+    assert_equal __, 0.object_id
+    assert_equal __, 1.object_id
+    assert_equal __, 2.object_id
+    assert_equal __, 100.object_id
+
+    # THINK ABOUT IT:
+    # What pattern do the object IDs for small integers follow?
+  end
+
+  def test_clone_creates_a_different_object
+    obj = Object.new
+    copy = obj.clone
+
+    assert_equal __, obj           != copy
+    assert_equal __, obj.object_id != copy.object_id
+  end
+end

koans/path_to_enlightenment.rb

@@ -4,6 +4,7 @@ $LOAD_PATH << File.dirname(__FILE__)
 
 require 'about_asserts'
 require 'about_nil'
+require 'about_objects'
 require 'about_arrays'
 require 'about_array_assignment'
 require 'about_hashes'

src/about_objects.rb

@@ -0,0 +1,56 @@
+require File.expand_path(File.dirname(__FILE__) + '/edgecase')
+
+class AboutObjects < EdgeCase::Koan
+  def test_everything_is_an_object
+    assert_equal __(true), 1.is_a?(Object)
+    assert_equal __(true), 1.5.is_a?(Object)
+    assert_equal __(true), "string".is_a?(Object)
+    assert_equal __(true), nil.is_a?(Object)
+    assert_equal __(true), Object.is_a?(Object)
+  end
+
+  def test_objects_can_be_converted_to_strings
+    assert_equal __("123"), 123.to_s
+    assert_equal __(""), nil.to_s
+  end
+
+  def test_objects_can_be_inspected
+    assert_equal __("123"), 123.inspect
+    assert_equal __("nil"), nil.inspect
+  end
+
+  def test_every_object_has_an_id
+    obj = Object.new
+    assert_equal __(Fixnum), obj.object_id.class
+  end
+
+  def test_every_object_has_different_id
+    obj = Object.new
+    another_obj = Object.new
+    assert_equal __(true), obj.object_id != another_obj.object_id
+  end
+
+  def test_some_system_objects_always_have_the_same_id
+    assert_equal __(0), false.object_id
+    assert_equal __(2), true.object_id
+    assert_equal __(4), nil.object_id
+  end
+
+  def test_small_integers_have_fixed_ids
+    assert_equal __(1), 0.object_id
+    assert_equal __(3), 1.object_id
+    assert_equal __(5), 2.object_id
+    assert_equal __(201), 100.object_id
+
+    # THINK ABOUT IT:
+    # What pattern do the object IDs for small integers follow?
+  end
+
+  def test_clone_creates_a_different_object
+    obj = Object.new
+    copy = obj.clone
+
+    assert_equal __(true), obj           != copy
+    assert_equal __(true), obj.object_id != copy.object_id
+  end
+end

src/path_to_enlightenment.rb

@@ -4,6 +4,7 @@ $LOAD_PATH << File.dirname(__FILE__)
 
 require 'about_asserts'
 require 'about_nil'
+require 'about_objects'
 require 'about_arrays'
 require 'about_array_assignment'
 require 'about_hashes'