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diff --git a/spec/ruby/core/proc/curry_spec.rb b/spec/ruby/core/proc/curry_spec.rb
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+++ b/spec/ruby/core/proc/curry_spec.rb
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+require File.expand_path('../../../spec_helper', __FILE__)
+
+describe "Proc#curry" do
+  before :each do
+    @proc_add = Proc.new {|x,y,z| (x||0) + (y||0) + (z||0) }
+    @lambda_add = lambda {|x,y,z| (x||0) + (y||0) + (z||0) }
+  end
+
+  it "returns a Proc when called on a proc" do
+    p = proc { true }
+    p.curry.should be_an_instance_of(Proc)
+  end
+
+  it "returns a Proc when called on a lambda" do
+    p = lambda { true }
+    p.curry.should be_an_instance_of(Proc)
+  end
+
+  it "calls the curried proc with the arguments if sufficient arguments have been given" do
+    @proc_add.curry[1][2][3].should == 6
+    @lambda_add.curry[1][2][3].should == 6
+  end
+
+  it "returns a Proc that consumes the remainder of the arguments unless sufficient arguments have been given" do
+    proc2 = @proc_add.curry[1][2]
+    proc2.should be_an_instance_of(Proc)
+    proc2.call(3).should == 6
+
+    lambda2 = @lambda_add.curry[1][2]
+    lambda2.should be_an_instance_of(Proc)
+    lambda2.call(3).should == 6
+
+    @proc_add.curry.call(1,2,3).should == 6
+    @lambda_add.curry.call(1,2,3).should == 6
+  end
+
+  it "can be called multiple times on the same Proc" do
+    @proc_add.curry
+    lambda { @proc_add.curry }.should_not raise_error
+
+    @lambda_add.curry
+    lambda { @lambda_add.curry }.should_not raise_error
+  end
+
+  it "can be passed superfluous arguments if created from a proc" do
+    @proc_add.curry[1,2,3,4].should == 6
+
+    @proc_add.curry[1,2].curry[3,4,5,6].should == 6
+  end
+
+  it "raises an ArgumentError if passed superfluous arguments when created from a lambda" do
+    lambda { @lambda_add.curry[1,2,3,4] }.should raise_error(ArgumentError)
+    lambda { @lambda_add.curry[1,2].curry[3,4,5,6] }.should raise_error(ArgumentError)
+  end
+
+  it "returns Procs with arities of -1" do
+    @proc_add.curry.arity.should == -1
+    @lambda_add.curry.arity.should == -1
+    l = lambda { |*a| }
+    l.curry.arity.should == -1
+  end
+
+  it "produces Procs that raise ArgumentError for #binding" do
+    lambda do
+      @proc_add.curry.binding
+    end.should raise_error(ArgumentError)
+  end
+
+  it "produces Procs that return [[:rest]] for #parameters" do
+    @proc_add.curry.parameters.should == [[:rest]]
+  end
+
+  it "produces Procs that return nil for #source_location" do
+    @proc_add.curry.source_location.should == nil
+  end
+
+  it "produces Procs that can be passed as the block for instance_exec" do
+    curried = @proc_add.curry.call(1, 2)
+
+    instance_exec(3, &curried).should == 6
+  end
+
+  it "combines arguments and calculates incoming arity accurately for successively currying" do
+    l = lambda{|a,b,c| a+b+c }
+    l1 = l.curry.call(1)
+    # the l1 currying seems unnecessary, but it triggered the original issue
+    l2 = l1.curry.call(2)
+
+    l2.curry.call(3).should == 6
+    l1.curry.call(2,3).should == 6
+  end
+end
+
+describe "Proc#curry with arity argument" do
+  before :each do
+    @proc_add = proc {|x,y,z| (x||0) + (y||0) + (z||0) }
+    @lambda_add = lambda {|x,y,z| (x||0) + (y||0) + (z||0) }
+  end
+
+  it "accepts an optional Integer argument for the arity" do
+    lambda { @proc_add.curry(3) }.should_not raise_error
+    lambda { @lambda_add.curry(3) }.should_not raise_error
+  end
+
+  it "returns a Proc when called on a proc" do
+    @proc_add.curry(3).should be_an_instance_of(Proc)
+  end
+
+  it "returns a Proc when called on a lambda" do
+    @lambda_add.curry(3).should be_an_instance_of(Proc)
+  end
+
+  # [ruby-core:24127]
+  it "retains the lambda-ness of the Proc on which its called" do
+    @lambda_add.curry(3).lambda?.should be_true
+    @proc_add.curry(3).lambda?.should be_false
+  end
+
+  it "raises an ArgumentError if called on a lambda that requires more than _arity_ arguments" do
+    lambda { @lambda_add.curry(2) }.should raise_error(ArgumentError)
+    lambda { lambda{|x, y, z, *more|}.curry(2) }.should raise_error(ArgumentError)
+  end
+
+  it 'returns a Proc if called on a lambda that requires fewer than _arity_ arguments but may take more' do
+    lambda{|a, b, c, d=nil, e=nil|}.curry(4).should be_an_instance_of(Proc)
+    lambda{|a, b, c, d=nil, *e|}.curry(4).should be_an_instance_of(Proc)
+    lambda{|a, b, c, *d|}.curry(4).should be_an_instance_of(Proc)
+  end
+
+  it "raises an ArgumentError if called on a lambda that requires fewer than _arity_ arguments" do
+    lambda { @lambda_add.curry(4) }.should raise_error(ArgumentError)
+    lambda { lambda { true }.curry(1) }.should raise_error(ArgumentError)
+    lambda { lambda {|a, b=nil|}.curry(5) }.should raise_error(ArgumentError)
+    lambda { lambda {|a, &b|}.curry(2) }.should raise_error(ArgumentError)
+    lambda { lambda {|a, b=nil, &c|}.curry(3) }.should raise_error(ArgumentError)
+  end
+
+  it "calls the curried proc with the arguments if _arity_ arguments have been given" do
+    @proc_add.curry(3)[1][2][3].should == 6
+    @lambda_add.curry(3)[1][2][3].should == 6
+  end
+
+  it "returns a Proc that consumes the remainder of the arguments when fewer than _arity_ arguments are given" do
+    proc2 = @proc_add.curry(3)[1][2]
+    proc2.should be_an_instance_of(Proc)
+    proc2.call(3).should == 6
+
+    lambda2 = @lambda_add.curry(3)[1][2]
+    lambda2.should be_an_instance_of(Proc)
+    lambda2.call(3).should == 6
+  end
+
+  it "can be specified multiple times on the same Proc" do
+    @proc_add.curry(2)
+    lambda { @proc_add.curry(1) }.should_not raise_error
+
+    @lambda_add.curry(3)
+    lambda { @lambda_add.curry(3) }.should_not raise_error
+  end
+
+  it "can be passed more than _arity_ arguments if created from a proc" do
+    lambda { @proc_add.curry(3)[1,2,3,4].should == 6 }.should_not
+      raise_error(ArgumentError)
+    lambda { @proc_add.curry(1)[1,2].curry(3)[3,4,5,6].should == 6 }.should_not
+      raise_error(ArgumentError)
+  end
+
+  it "raises an ArgumentError if passed more than _arity_ arguments when created from a lambda" do
+    lambda { @lambda_add.curry(3)[1,2,3,4] }.should raise_error(ArgumentError)
+    lambda { @lambda_add.curry(1)[1,2].curry(3)[3,4,5,6] }.should raise_error(ArgumentError)
+  end
+
+  it "returns Procs with arities of -1 regardless of the value of _arity_" do
+    @proc_add.curry(1).arity.should == -1
+    @proc_add.curry(2).arity.should == -1
+    @lambda_add.curry(3).arity.should == -1
+    l = lambda { |*a| }
+    l.curry(3).arity.should == -1
+  end
+end