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require_relative '../../spec_helper'
require_relative 'fixtures/classes'
describe "Kernel#instance_variable_set" do
it "sets the value of the specified instance variable" do
class Dog
def initialize(p1, p2)
@a, @b = p1, p2
end
end
Dog.new('cat', 99).instance_variable_set(:@a, 'dog').should == "dog"
end
it "sets the value of the instance variable when no instance variables exist yet" do
class NoVariables; end
NoVariables.new.instance_variable_set(:@a, "new").should == "new"
end
it "raises a NameError exception if the argument is not of form '@x'" do
class NoDog; end
lambda { NoDog.new.instance_variable_set(:c, "cat") }.should raise_error(NameError)
end
it "raises a NameError exception if the argument is an invalid instance variable name" do
class DigitDog; end
lambda { DigitDog.new.instance_variable_set(:"@0", "cat") }.should raise_error(NameError)
end
it "raises a NameError when the argument is '@'" do
class DogAt; end
lambda { DogAt.new.instance_variable_set(:"@", "cat") }.should raise_error(NameError)
end
it "raises a TypeError if the instance variable name is a Fixnum" do
lambda { "".instance_variable_set(1, 2) }.should raise_error(TypeError)
end
it "raises a TypeError if the instance variable name is an object that does not respond to to_str" do
class KernelSpecs::A; end
lambda { "".instance_variable_set(KernelSpecs::A.new, 3) }.should raise_error(TypeError)
end
it "raises a NameError if the passed object, when coerced with to_str, does not start with @" do
class KernelSpecs::B
def to_str
":c"
end
end
lambda { "".instance_variable_set(KernelSpecs::B.new, 4) }.should raise_error(NameError)
end
it "raises a NameError if pass an object that cannot be a symbol" do
lambda { "".instance_variable_set(:c, 1) }.should raise_error(NameError)
end
it "accepts as instance variable name any instance of a class that responds to to_str" do
class KernelSpecs::C
def initialize
@a = 1
end
def to_str
"@a"
end
end
KernelSpecs::C.new.instance_variable_set(KernelSpecs::C.new, 2).should == 2
end
describe "on frozen objects" do
before :each do
klass = Class.new do
attr_reader :ivar
def initialize
@ivar = :origin
end
end
@frozen = klass.new.freeze
end
it "keeps stored object after any exceptions" do
lambda { @frozen.instance_variable_set(:@ivar, :replacement) }.should raise_error(Exception)
@frozen.ivar.should equal(:origin)
end
it "raises a #{frozen_error_class} when passed replacement is identical to stored object" do
lambda { @frozen.instance_variable_set(:@ivar, :origin) }.should raise_error(frozen_error_class)
end
it "raises a #{frozen_error_class} when passed replacement is different from stored object" do
lambda { @frozen.instance_variable_set(:@ivar, :replacement) }.should raise_error(frozen_error_class)
end
end
end
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