Added src directory

src/about_nil.rb

@@ -0,0 +1,38 @@
+require 'edgecase'
+
+class AboutNil < EdgeCase::Koan
+  def test_nil_is_an_object
+    assert_equal __(true), nil.is_a?(Object), "Unlike NULL in other languages"
+  end
+
+  def test_you_dont_get_null_pointer_errors_when_calling_methods_on_nil
+    # What happens when you call a method that doesn't exist.  The
+    # following begin/rescue/end code block captures the exception and
+    # make some assertions about it.
+    begin
+      nil.some_method_nil_doesnt_know_about
+    rescue Exception => ex
+      # What exception has been caught?
+      assert_equal __(NoMethodError), ex.class
+
+      # What message was attached to the exception?
+      # (HINT: replace __ with part of the error message.)
+      assert_match(/#{__("undefined method")}/, ex.message)
+    end
+  end
+
+  def test_nil_has_a_few_methods_defined_on_it
+    assert_equal __(true), nil.nil?
+    assert_equal __(""), nil.to_s
+    assert_equal __("nil"), nil.inspect
+
+    # THINK ABOUT IT:
+    #
+    # Is it better to use
+    #    obj.nil?
+    # or
+    #    obj == nil
+    # Why?
+  end
+
+end