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require File.expand_path(File.dirname(__FILE__) + '/edgecase')
class AboutClasses < EdgeCase::Koan
class Dog
end
def test_instances_of_classes_can_be_created_with_new
fido = Dog.new
assert_equal Dog, fido.class
end
# ------------------------------------------------------------------
class Dog2
def set_name(a_name)
@name = a_name
end
end
def test_instance_variables_can_be_set_by_assigning_to_them
fido = Dog2.new
assert_equal [], fido.instance_variables
fido.set_name("Fido")
assert_equal [:@name], fido.instance_variables
end
def test_instance_variables_cannot_be_accessed_outside_the_class
fido = Dog2.new
fido.set_name("Fido")
assert_raise(NoMethodError) do
fido.name
end
assert_raise(SyntaxError) do
eval "fido.@name"
# NOTE: Using eval because the above line is a syntax error.
end
end
def test_you_can_politely_ask_for_instance_variable_values
fido = Dog2.new
fido.set_name("Fido")
assert_equal "Fido", fido.instance_variable_get("@name")
end
def test_you_can_rip_the_value_out_using_instance_eval
fido = Dog2.new
fido.set_name("Fido")
assert_equal "Fido", fido.instance_eval("@name") # string version
assert_equal "Fido", fido.instance_eval { @name } # block version
end
# ------------------------------------------------------------------
class Dog3
def set_name(a_name)
@name = a_name
end
def name
@name
end
end
def test_you_can_create_accessor_methods_to_return_instance_variables
fido = Dog3.new
fido.set_name("Fido")
assert_equal __, fido.name
end
# ------------------------------------------------------------------
class Dog4
attr_reader :name
def set_name(a_name)
@name = a_name
end
end
def test_attr_reader_will_automatically_define_an_accessor
fido = Dog4.new
fido.set_name("Fido")
assert_equal __, fido.name
end
# ------------------------------------------------------------------
class Dog5
attr_accessor :name
end
def test_attr_accessor_will_automatically_define_both_read_and_write_accessors
fido = Dog5.new
fido.name = "Fido"
assert_equal __, fido.name
end
# ------------------------------------------------------------------
class Dog6
attr_reader :name
def initialize(initial_name)
@name = initial_name
end
end
def test_initialize_provides_initial_values_for_instance_variables
fido = Dog6.new("Fido")
assert_equal __, fido.name
end
def test_args_to_new_must_match_initialize
assert_raise(___) do
Dog6.new
end
# THINK ABOUT IT:
# Why is this so?
end
def test_different_objects_have_different_instance_variables
fido = Dog6.new("Fido")
rover = Dog6.new("Rover")
assert_equal __, rover.name != fido.name
end
# ------------------------------------------------------------------
class Dog7
attr_reader :name
def initialize(initial_name)
@name = initial_name
end
def get_self
self
end
def to_s
__
end
def inspect
"<Dog named '#{name}'>"
end
end
def test_inside_a_method_self_refers_to_the_containing_object
fido = Dog7.new("Fido")
fidos_self = fido.get_self
assert_equal __, fidos_self
end
def test_to_s_provides_a_string_version_of_the_object
fido = Dog7.new("Fido")
assert_equal __, fido.to_s
end
def test_to_s_is_used_in_string_interpolation
fido = Dog7.new("Fido")
assert_equal __, "My dog is #{fido}"
end
def test_inspect_provides_a_more_complete_string_version
fido = Dog7.new("Fido")
assert_equal __, fido.inspect
end
def test_all_objects_support_to_s_and_inspect
array = [1,2,3]
assert_equal __, array.to_s
assert_equal __, array.inspect
assert_equal __, "STRING".to_s
assert_equal __, "STRING".inspect
end
end