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diff --git a/spec/ruby/library/prime/each_spec.rb b/spec/ruby/library/prime/each_spec.rb
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+require File.expand_path('../../../spec_helper', __FILE__)
+require 'prime'
+
+describe :prime_each, shared: true do
+  before :each do
+    ScratchPad.record []
+  end
+
+  it "enumerates primes" do
+    primes = Prime.instance
+    result = []
+
+    primes.each { |p|
+      result << p
+      break if p > 10
+    }
+
+    result.should == [2, 3, 5, 7, 11]
+  end
+
+  it "yields ascending primes to the block" do
+    previous = 1
+    @object.each do |prime|
+      break if prime > 1000
+      ScratchPad << prime
+      prime.should > previous
+      previous = prime
+    end
+
+    all_prime = true
+    ScratchPad.recorded.all? do |prime|
+      all_prime &&= (2..Math.sqrt(prime)).all? { |d| prime % d != 0 }
+    end
+
+    all_prime.should be_true
+  end
+
+  it "returns the last evaluated expression in the passed block" do
+    @object.each { break :value }.should equal(:value)
+  end
+
+  describe "when not passed a block" do
+    before :each do
+      @prime_enum = @object.each
+    end
+
+    it "returns an object that is Enumerable" do
+      @prime_enum.each.should be_kind_of(Enumerable)
+    end
+
+    it "returns an object that responds to #with_index" do
+      @prime_enum.should respond_to(:with_index)
+    end
+
+    it "returns an object that responds to #with_object" do
+      @prime_enum.should respond_to(:with_object)
+    end
+
+    it "returns an object that responds to #next" do
+      @prime_enum.should respond_to(:next)
+    end
+
+    it "returns an object that responds to #rewind" do
+      @prime_enum.should respond_to(:rewind)
+    end
+
+    it "yields primes starting at 2 independent of prior enumerators" do
+      @prime_enum.next.should == 2
+      @prime_enum.next.should == 3
+
+      @object.each { |prime| break prime }.should == 2
+    end
+
+    it "returns an enumerator that yields previous primes when #rewind is called" do
+      @prime_enum.next.should == 2
+      @prime_enum.next.should == 3
+      @prime_enum.rewind
+      @prime_enum.next.should == 2
+    end
+
+    it "returns independent enumerators" do
+      enum = @object.each
+      enum.next.should == 2
+      enum.next.should == 3
+
+      @prime_enum.next.should == 2
+
+      enum.next.should == 5
+    end
+  end
+end
+
+describe :prime_each_with_arguments, shared: true do
+  before :each do
+    ScratchPad.record []
+  end
+
+  it "yields ascending primes less than or equal to the argument" do
+    bound = 1000
+    previous = 1
+    @object.each(bound) do |prime|
+      ScratchPad << prime
+      prime.should > previous
+      previous = prime
+    end
+
+    ScratchPad.recorded.all? do |prime|
+      (2..Math.sqrt(prime)).all? { |d| prime % d != 0 }
+    end.should be_true
+
+    ScratchPad.recorded.all? { |prime| prime <= bound }.should be_true
+  end
+
+  it "returns nil when no prime is generated" do
+    @object.each(1) { :value }.should be_nil
+  end
+
+  it "yields primes starting at 2 independent of prior enumeration" do
+    @object.each(10) { |prime| prime }.should == 7
+    @object.each(10) { |prime| break prime }.should == 2
+  end
+
+  it "accepts a pseudo-prime generator as the second argument" do
+    generator = mock('very bad pseudo-prime generator')
+    generator.should_receive(:upper_bound=).with(100)
+    generator.should_receive(:each).and_yield(2).and_yield(3).and_yield(4)
+
+    @object.each(100, generator) { |prime| ScratchPad << prime }
+    ScratchPad.recorded.should == [2, 3, 4]
+  end
+
+  describe "when not passed a block" do
+    it "returns an object that returns primes less than or equal to the bound" do
+      bound = 100
+      @object.each(bound).all? { |prime| prime <= bound }.should be_true
+    end
+  end
+end
+
+describe "Prime.each" do
+  it_behaves_like :prime_each, :each, Prime
+end
+
+describe "Prime.each" do
+  it_behaves_like :prime_each_with_arguments, :each, Prime
+end
+
+describe "Prime#each with Prime.instance" do
+  it_behaves_like :prime_each, :each, Prime.instance
+end
+
+describe "Prime#each with Prime.instance" do
+  it_behaves_like :prime_each_with_arguments, :each, Prime.instance
+end
+
+describe "Prime#each with Prime.instance" do
+  before :each do
+    @object = Prime.instance
+  end
+
+  it_behaves_like :prime_each, :each
+
+  it "resets the enumerator with each call" do
+    @object.each { |prime| break if prime > 10 }
+    @object.each { |prime| break prime }.should == 2
+  end
+end