* adds the spec for Array#<=> on 1.9

* adds more description on 1.8.

1.8/core/array/comparison_spec.rb

@@ -30,6 +30,40 @@
     ([1, 1, 1] <=> [1, 1]).should == +1
   end
 
+  it "returns -1 if the arrays have same length and a pair of corresponding elements returns -1 for <=>" do
+    eq_l = mock('an object equal to the other')
+    eq_r = mock('an object equal to the other')
+    eq_l.should_receive(:<=>).with(eq_r).any_number_of_times.and_return(0)
+
+    less = mock('less than the other')
+    greater = mock('greater then the other')
+    less.should_receive(:<=>).with(greater).any_number_of_times.and_return(-1)
+
+    rest = mock('an rest element of the arrays')
+    rest.should_receive(:<=>).with(rest).any_number_of_times.and_return(0)
+    lhs = [eq_l, eq_l, less, rest]
+    rhs = [eq_r, eq_r, greater, rest]
+
+    (lhs <=> rhs).should == -1
+  end
+
+  it "returns +1 if the arrays have same length and a pair of corresponding elements returns +1 for <=>" do
+    eq_l = mock('an object equal to the other')
+    eq_r = mock('an object equal to the other')
+    eq_l.should_receive(:<=>).with(eq_r).any_number_of_times.and_return(0)
+
+    greater = mock('greater then the other')
+    less = mock('less than the other')
+    greater.should_receive(:<=>).with(less).any_number_of_times.and_return(+1)
+
+    rest = mock('an rest element of the arrays')
+    rest.should_receive(:<=>).with(rest).any_number_of_times.and_return(0)
+    lhs = [eq_l, eq_l, greater, rest]
+    rhs = [eq_r, eq_r, less, rest]
+
+    (lhs <=> rhs).should == +1
+  end
+
   it "properly handles recursive arrays" do
     empty = ArraySpecs.empty_recursive_array
     (empty <=> empty).should == 0

1.9/core/array/comparison_spec.rb

@@ -0,0 +1,100 @@
+require File.dirname(__FILE__) + '/../../spec_helper'
+require File.dirname(__FILE__) + '/fixtures/classes'
+
+describe "Array#<=>" do
+  it "calls <=> left to right and return first non-0 result" do
+    [-1, +1, nil, "foobar"].each do |result|
+      lhs = Array.new(3) { mock("#{result}") }
+      rhs = Array.new(3) { mock("#{result}") }
+
+      lhs[0].should_receive(:<=>).with(rhs[0]).and_return(0)
+      lhs[1].should_receive(:<=>).with(rhs[1]).and_return(result)
+      lhs[2].should_not_receive(:<=>)
+
+      (lhs <=> rhs).should == result
+    end
+  end
+
+  it "returns 0 if the arrays are equal" do
+    ([] <=> []).should == 0
+    ([1, 2, 3, 4, 5, 6] <=> [1, 2, 3, 4, 5.0, 6.0]).should == 0
+  end
+
+  it "returns -1 if the array is shorter than the other array" do
+    ([] <=> [1]).should == -1
+    ([1, 1] <=> [1, 1, 1]).should == -1
+  end
+
+  it "returns +1 if the array is longer than the other array" do
+    ([1] <=> []).should == +1
+    ([1, 1, 1] <=> [1, 1]).should == +1
+  end
+
+  it "returns -1 if the arrays have same length and a pair of corresponding elements returns -1 for <=>" do
+    eq_l = mock('an object equal to the other')
+    eq_r = mock('an object equal to the other')
+    eq_l.should_receive(:<=>).with(eq_r).any_number_of_times.and_return(0)
+
+    less = mock('less than the other')
+    greater = mock('greater then the other')
+    less.should_receive(:<=>).with(greater).any_number_of_times.and_return(-1)
+
+    rest = mock('an rest element of the arrays')
+    rest.should_receive(:<=>).with(rest).any_number_of_times.and_return(0)
+    lhs = [eq_l, eq_l, less, rest]
+    rhs = [eq_r, eq_r, greater, rest]
+
+    (lhs <=> rhs).should == -1
+  end
+
+  it "returns +1 if the arrays have same length and a pair of corresponding elements returns +1 for <=>" do
+    eq_l = mock('an object equal to the other')
+    eq_r = mock('an object equal to the other')
+    eq_l.should_receive(:<=>).with(eq_r).any_number_of_times.and_return(0)
+
+    greater = mock('greater then the other')
+    less = mock('less than the other')
+    greater.should_receive(:<=>).with(less).any_number_of_times.and_return(+1)
+
+    rest = mock('an rest element of the arrays')
+    rest.should_receive(:<=>).with(rest).any_number_of_times.and_return(0)
+    lhs = [eq_l, eq_l, greater, rest]
+    rhs = [eq_r, eq_r, less, rest]
+
+    (lhs <=> rhs).should == +1
+  end
+
+  it "properly handles recursive arrays" do
+    empty = ArraySpecs.empty_recursive_array
+    (empty <=> empty).should == 0
+    (empty <=> []).should == 1
+    ([] <=> empty).should == -1
+
+    (ArraySpecs.recursive_array <=> []).should == 1
+    ([] <=> ArraySpecs.recursive_array).should == -1
+
+    (ArraySpecs.recursive_array <=> ArraySpecs.empty_recursive_array).should == nil
+
+    array = ArraySpecs.recursive_array
+    (array <=> array).should == 0
+  end
+
+  it "tries to convert the passed argument to an Array using #to_ary" do
+    obj = mock('to_ary')
+    obj.stub!(:to_ary).and_return([1, 2, 3])
+    ([4, 5] <=> obj).should == ([4, 5] <=> obj.to_ary)
+  end
+
+  it "checks whether the passed argument responds to #to_ary" do
+    obj = mock('method_missing to_ary')
+    obj.should_receive(:respond_to?).with(:to_ary).any_number_of_times.and_return(true)
+    obj.should_receive(:method_missing).with(:to_ary).and_return([4, 5])
+    ([4, 5] <=> obj).should == 0
+  end  
+
+  it "does not call #to_ary on Array subclasses" do
+    obj = ArraySpecs::ToAryArray[5, 6, 7]
+    obj.should_not_receive(:to_ary)
+    ([5, 6, 7] <=> obj).should == 0
+  end
+end