1 files changed, 361 insertions, 0 deletions
diff --git a/spec/ruby/core/module/prepend_spec.rb b/spec/ruby/core/module/prepend_spec.rb
new file mode 100644
index 0000000000..c0cce616a2
--- /dev/null
+++ b/spec/ruby/core/module/prepend_spec.rb
@@ -0,0 +1,361 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes', __FILE__)
+
+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
+    lambda { 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
+    lambda { 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 "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
+    lambda { 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
+    lambda {
+      module ModuleSpecs::P
+        prepend ModuleSpecs::P
+      end
+    }.should raise_error(ArgumentError)
+  end
+
+  ruby_version_is ''...'2.4' do
+    it "accepts no-arguments" do
+      lambda {
+        Module.new do
+          prepend
+        end
+      }.should_not raise_error
+    end
+  end
+
+  ruby_version_is '2.4' do
+    it "doesn't accept no-arguments" do
+      lambda {
+        Module.new do
+          prepend
+        end
+      }.should raise_error(ArgumentError)
+    end
+  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