require_relative '../../spec_helper' require_relative 'fixtures/classes' describe "Module#prepend" do it "is a public method" do Module.should have_public_instance_method(:prepend, false) end it "does not affect the superclass" do Class.new { prepend Module.new }.superclass.should == Object end it "calls #prepend_features(self) in reversed order on each module" do ScratchPad.record [] m = Module.new do def self.prepend_features(mod) ScratchPad << [ self, mod ] end end m2 = Module.new do def self.prepend_features(mod) ScratchPad << [ self, mod ] end end m3 = Module.new do def self.prepend_features(mod) ScratchPad << [ self, mod ] end end c = Class.new { prepend(m, m2, m3) } ScratchPad.recorded.should == [ [ m3, c], [ m2, c ], [ m, c ] ] end it "raises a TypeError when the argument is not a Module" do -> { ModuleSpecs::Basic.prepend(Class.new) }.should raise_error(TypeError) end it "does not raise a TypeError when the argument is an instance of a subclass of Module" do -> { ModuleSpecs::SubclassSpec.prepend(ModuleSpecs::Subclass.new) }.should_not raise_error(TypeError) end it "imports constants" do m1 = Module.new m1::MY_CONSTANT = 1 m2 = Module.new { prepend(m1) } m2.constants.should include(:MY_CONSTANT) end it "imports instance methods" do Module.new { prepend ModuleSpecs::A }.instance_methods.should include(:ma) end it "does not import methods to modules and classes" do Module.new { prepend ModuleSpecs::A }.methods.should_not include(:ma) end it "allows wrapping methods" do m = Module.new { def calc(x) super + 3 end } c = Class.new { def calc(x) x*2 end } c.prepend(m) c.new.calc(1).should == 5 end it "also prepends included modules" do a = Module.new { def calc(x) x end } b = Module.new { include a } c = Class.new { prepend b } c.new.calc(1).should == 1 end it "prepends multiple modules in the right order" do m1 = Module.new { def chain; super << :m1; end } m2 = Module.new { def chain; super << :m2; end; prepend(m1) } c = Class.new { def chain; [:c]; end; prepend(m2) } c.new.chain.should == [:c, :m2, :m1] end it "includes prepended modules in ancestors" do m = Module.new Class.new { prepend(m) }.ancestors.should include(m) end it "reports the prepended module as the method owner" do m = Module.new { def meth; end } c = Class.new { def meth; end; prepend(m) } c.new.method(:meth).owner.should == m end it "reports the prepended module as the unbound method owner" do m = Module.new { def meth; end } c = Class.new { def meth; end; prepend(m) } c.instance_method(:meth).owner.should == m c.public_instance_method(:meth).owner.should == m end it "causes the prepended module's method to be aliased by alias_method" do m = Module.new { def meth; :m end } c = Class.new { def meth; :c end; prepend(m); alias_method :alias, :meth } c.new.alias.should == :m end it "reports the class for the owner of an aliased method on the class" do m = Module.new c = Class.new { prepend(m); def meth; :c end; alias_method :alias, :meth } c.instance_method(:alias).owner.should == c end it "reports the class for the owner of a method aliased from the prepended module" do m = Module.new { def meth; :m end } c = Class.new { prepend(m); alias_method :alias, :meth } c.instance_method(:alias).owner.should == c end it "sees an instance of a prepended class as kind of the prepended module" do m = Module.new c = Class.new { prepend(m) } c.new.should be_kind_of(m) end it "keeps the module in the chain when dupping the class" do m = Module.new c = Class.new { prepend(m) } c.dup.new.should be_kind_of(m) end it "keeps the module in the chain when dupping an intermediate module" do m1 = Module.new { def calc(x) x end } m2 = Module.new { prepend(m1) } c1 = Class.new { prepend(m2) } m2dup = m2.dup m2dup.ancestors.should == [m2dup,m1,m2] c2 = Class.new { prepend(m2dup) } c1.ancestors[0,3].should == [m1,m2,c1] c1.new.should be_kind_of(m1) c2.ancestors[0,4].should == [m2dup,m1,m2,c2] c2.new.should be_kind_of(m1) end it "depends on prepend_features to add the module" do m = Module.new { def self.prepend_features(mod) end } Class.new { prepend(m) }.ancestors.should_not include(m) end it "adds the module in the subclass chains" do parent = Class.new { def chain; [:parent]; end } child = Class.new(parent) { def chain; super << :child; end } mod = Module.new { def chain; super << :mod; end } parent.prepend(mod) parent.ancestors[0,2].should == [mod, parent] child.ancestors[0,3].should == [child, mod, parent] parent.new.chain.should == [:parent, :mod] child.new.chain.should == [:parent, :mod, :child] end it "inserts a later prepended module into the chain" do m1 = Module.new { def chain; super << :m1; end } m2 = Module.new { def chain; super << :m2; end } c1 = Class.new { def chain; [:c1]; end; prepend m1 } c2 = Class.new(c1) { def chain; super << :c2; end } c2.new.chain.should == [:c1, :m1, :c2] c1.prepend(m2) c2.new.chain.should == [:c1, :m1, :m2, :c2] end it "works with subclasses" do m = Module.new do def chain super << :module end end c = Class.new do prepend m def chain [:class] end end s = Class.new(c) do def chain super << :subclass end end s.new.chain.should == [:class, :module, :subclass] end it "throws a NoMethodError when there is no more superclass" do m = Module.new do def chain super << :module end end c = Class.new do prepend m def chain super << :class end end -> { c.new.chain }.should raise_error(NoMethodError) end it "calls prepended after prepend_features" do ScratchPad.record [] m = Module.new do def self.prepend_features(klass) ScratchPad << [:prepend_features, klass] end def self.prepended(klass) ScratchPad << [:prepended, klass] end end c = Class.new { prepend(m) } ScratchPad.recorded.should == [[:prepend_features, c], [:prepended, c]] end it "detects cyclic prepends" do -> { module ModuleSpecs::P prepend ModuleSpecs::P end }.should raise_error(ArgumentError) end it "doesn't accept no-arguments" do -> { Module.new do prepend end }.should raise_error(ArgumentError) end it "returns the class it's included into" do m = Module.new r = nil c = Class.new { r = prepend m } r.should == c end it "clears any caches" do module ModuleSpecs::M3 module PM1 def foo :m1 end end module PM2 def foo :m2 end end klass = Class.new do prepend PM1 def get foo end end o = klass.new o.get.should == :m1 klass.class_eval do prepend PM2 end o.get.should == :m2 end end it "supports super when the module is prepended into a singleton class" do ScratchPad.record [] mod = Module.new do def self.inherited(base) super end end module_with_singleton_class_prepend = Module.new do singleton_class.prepend(mod) end klass = Class.new(ModuleSpecs::RecordIncludedModules) do include module_with_singleton_class_prepend end ScratchPad.recorded.should == klass end it "supports super when the module is prepended into a singleton class with a class super" do ScratchPad.record [] base_class = Class.new(ModuleSpecs::RecordIncludedModules) do def self.inherited(base) super end end prepended_module = Module.new base_class.singleton_class.prepend(prepended_module) child_class = Class.new(base_class) ScratchPad.recorded.should == child_class end it "does not interfere with a define_method super in the original class" do base_class = Class.new do def foo(ary) ary << 1 end end child_class = Class.new(base_class) do define_method :foo do |ary| ary << 2 super(ary) end end prep_mod = Module.new do def foo(ary) ary << 3 super(ary) end end child_class.prepend(prep_mod) ary = [] child_class.new.foo(ary) ary.should == [3, 2, 1] end describe "called on a module" do describe "included into a class" it "does not obscure the module's methods from reflective access" do mod = Module.new do def foo; end end cls = Class.new do include mod end pre = Module.new mod.prepend pre cls.instance_methods.should include(:foo) end end end