Cleaning up the specs.

8 files changed, 331 insertions, 345 deletions

diff --git a/spec/diff_lcs_sdiff_spec.rb b/spec/diff_lcs_sdiff_spec.rb
deleted file mode 100644
index b6a3f10..0000000
--- a/spec/diff_lcs_sdiff_spec.rb
+++ /dev/null
@@ -1,180 +0,0 @@
-# -*- ruby encoding: utf-8 -*-
-
-require 'spec_helper'
-
-describe "Diff::LCS.sdiff should compare sequences correctly" do
-  include Diff::LCS::SpecHelper::Matchers
-
-  def do_sdiff_comparison(s1, s2, forward_sdiff)
-    sdiff_s1_s2 = Diff::LCS.sdiff(s1, s2)
-    sdiff_s2_s1 = Diff::LCS.sdiff(s2, s1)
-
-    sdiff_s1_s2.should == context_diff(forward_sdiff)
-    sdiff_s2_s1.should == context_diff(reverse_sdiff(forward_sdiff))
-  end
-
-  it "sequence-a" do
-    do_sdiff_comparison(seq1, seq2, correct_forward_sdiff)
-  end
-
-  it "sequence-b" do
-    s1 = %w(abc def yyy xxx ghi jkl)
-    s2 = %w(abc dxf xxx ghi jkl)
-    forward_sdiff = [
-      [ '=', [ 0, 'abc' ], [ 0, 'abc' ] ],
-      [ '!', [ 1, 'def' ], [ 1, 'dxf' ] ],
-      [ '-', [ 2, 'yyy' ], [ 2,  nil  ] ],
-      [ '=', [ 3, 'xxx' ], [ 2, 'xxx' ] ],
-      [ '=', [ 4, 'ghi' ], [ 3, 'ghi' ] ],
-      [ '=', [ 5, 'jkl' ], [ 4, 'jkl' ] ]
-    ]
-
-    do_sdiff_comparison(s1, s2, forward_sdiff)
-  end
-
-  it "sequence-c" do
-    s1 = %w(a b c d e)
-    s2 = %w(a e)
-    forward_sdiff = [
-      [ '=', [ 0, 'a' ], [ 0, 'a' ] ],
-      [ '-', [ 1, 'b' ], [ 1, nil ] ],
-      [ '-', [ 2, 'c' ], [ 1, nil ] ],
-      [ '-', [ 3, 'd' ], [ 1, nil ] ],
-      [ '=', [ 4, 'e' ], [ 1, 'e' ] ] ]
-    do_sdiff_comparison(s1, s2, forward_sdiff)
-  end
-
-  it "sequence-d" do
-    s1 = %w(a e)
-    s2 = %w(a b c d e)
-    forward_sdiff = [
-      [ '=', [ 0, 'a' ], [ 0, 'a' ] ],
-      [ '+', [ 1, nil ], [ 1, 'b' ] ],
-      [ '+', [ 1, nil ], [ 2, 'c' ] ],
-      [ '+', [ 1, nil ], [ 3, 'd' ] ],
-      [ '=', [ 1, 'e' ], [ 4, 'e' ] ] ]
-    do_sdiff_comparison(s1, s2, forward_sdiff)
-  end
-
-  it "sequence-e" do
-    s1 = %w(v x a e)
-    s2 = %w(w y a b c d e)
-    forward_sdiff = [
-      [ '!', [ 0, 'v' ], [ 0, 'w' ] ],
-      [ '!', [ 1, 'x' ], [ 1, 'y' ] ],
-      [ '=', [ 2, 'a' ], [ 2, 'a' ] ],
-      [ '+', [ 3, nil ], [ 3, 'b' ] ],
-      [ '+', [ 3, nil ], [ 4, 'c' ] ],
-      [ '+', [ 3, nil ], [ 5, 'd' ] ],
-      [ '=', [ 3, 'e' ], [ 6, 'e' ] ] ]
-    do_sdiff_comparison(s1, s2, forward_sdiff)
-  end
-
-  it "sequence-f" do
-    s1 = %w(x a e)
-    s2 = %w(a b c d e)
-    forward_sdiff = [
-      [ '-', [ 0, 'x' ], [ 0, nil ] ],
-      [ '=', [ 1, 'a' ], [ 0, 'a' ] ],
-      [ '+', [ 2, nil ], [ 1, 'b' ] ],
-      [ '+', [ 2, nil ], [ 2, 'c' ] ],
-      [ '+', [ 2, nil ], [ 3, 'd' ] ],
-      [ '=', [ 2, 'e' ], [ 4, 'e' ] ] ]
-    do_sdiff_comparison(s1, s2, forward_sdiff)
-  end
-
-  it "sequence-g" do
-    s1 = %w(a e)
-    s2 = %w(x a b c d e)
-    forward_sdiff = [
-      [ '+', [ 0, nil ], [ 0, 'x' ] ],
-      [ '=', [ 0, 'a' ], [ 1, 'a' ] ],
-      [ '+', [ 1, nil ], [ 2, 'b' ] ],
-      [ '+', [ 1, nil ], [ 3, 'c' ] ],
-      [ '+', [ 1, nil ], [ 4, 'd' ] ],
-      [ '=', [ 1, 'e' ], [ 5, 'e' ] ] ]
-    do_sdiff_comparison(s1, s2, forward_sdiff)
-  end
-
-  it "sequence-h" do
-    s1 = %w(a e v)
-    s2 = %w(x a b c d e w x)
-    forward_sdiff = [
-      [ '+', [ 0, nil ], [ 0, 'x' ] ],
-      [ '=', [ 0, 'a' ], [ 1, 'a' ] ],
-      [ '+', [ 1, nil ], [ 2, 'b' ] ],
-      [ '+', [ 1, nil ], [ 3, 'c' ] ],
-      [ '+', [ 1, nil ], [ 4, 'd' ] ],
-      [ '=', [ 1, 'e' ], [ 5, 'e' ] ],
-      [ '!', [ 2, 'v' ], [ 6, 'w' ] ],
-      [ '+', [ 3, nil ], [ 7, 'x' ] ] ]
-    do_sdiff_comparison(s1, s2, forward_sdiff)
-  end
-
-  it "sequence-i" do
-    s1 = %w()
-    s2 = %w(a b c)
-    forward_sdiff = [
-      [ '+', [ 0, nil ], [ 0, 'a' ] ],
-      [ '+', [ 0, nil ], [ 1, 'b' ] ],
-      [ '+', [ 0, nil ], [ 2, 'c' ] ] ]
-    do_sdiff_comparison(s1, s2, forward_sdiff)
-  end
-
-  it "sequence-j" do
-    s1 = %w(a b c)
-    s2 = %w()
-    forward_sdiff = [
-      [ '-', [ 0, 'a' ], [ 0, nil ] ],
-      [ '-', [ 1, 'b' ], [ 0, nil ] ],
-      [ '-', [ 2, 'c' ], [ 0, nil ] ] ]
-    do_sdiff_comparison(s1, s2, forward_sdiff)
-  end
-
-  it "sequence-k" do
-    s1 = %w(a b c)
-    s2 = %w(1)
-    forward_sdiff = [
-      [ '!', [ 0, 'a' ], [ 0, '1' ] ],
-      [ '-', [ 1, 'b' ], [ 1, nil ] ],
-      [ '-', [ 2, 'c' ], [ 1, nil ] ] ]
-    do_sdiff_comparison(s1, s2, forward_sdiff)
-  end
-
-  it "sequence-l" do
-    s1 = %w(a b c)
-    s2 = %w(c)
-    forward_sdiff = [
-      [ '-', [ 0, 'a' ], [ 0, nil ] ],
-      [ '-', [ 1, 'b' ], [ 0, nil ] ],
-      [ '=', [ 2, 'c' ], [ 0, 'c' ] ]
-    ]
-    do_sdiff_comparison(s1, s2, forward_sdiff)
-  end
-
-  it "sequence-m" do
-    s1 = %w(abcd efgh ijkl mnop)
-    s2 = []
-    forward_sdiff = [
-      [ '-', [ 0, 'abcd' ], [ 0, nil ] ],
-      [ '-', [ 1, 'efgh' ], [ 0, nil ] ],
-      [ '-', [ 2, 'ijkl' ], [ 0, nil ] ],
-      [ '-', [ 3, 'mnop' ], [ 0, nil ] ]
-    ]
-    do_sdiff_comparison(s1, s2, forward_sdiff)
-  end
-
-  it "sequence-n" do
-    s1 = []
-    s2 = %w(abcd efgh ijkl mnop)
-    forward_sdiff = [
-      [ '+', [ 0, nil ], [ 0, 'abcd' ] ],
-      [ '+', [ 0, nil ], [ 1, 'efgh' ] ],
-      [ '+', [ 0, nil ], [ 2, 'ijkl' ] ],
-      [ '+', [ 0, nil ], [ 3, 'mnop' ] ]
-    ]
-    do_sdiff_comparison(s1, s2, forward_sdiff)
-  end
-end
-
-# vim: ft=ruby
diff --git a/spec/diff_lcs_diff_spec.rb b/spec/diff_spec.rb
index 43ea5c7..d2c78a2 100644
--- a/spec/diff_lcs_diff_spec.rb
+++ b/spec/diff_spec.rb
@@ -5,11 +5,13 @@ require 'spec_helper'
 describe "Diff::LCS.diff" do
   include Diff::LCS::SpecHelper::Matchers
 
-  it "should correctly diff the sequences" do
+  it "should correctly diff seq1 to seq2" do
     diff_s1_s2 = Diff::LCS.diff(seq1, seq2)
-    diff_s2_s1 = Diff::LCS.diff(seq2, seq1)
-
     change_diff(correct_forward_diff).should == diff_s1_s2
+  end
+
+  it "should correctly diff seq2 to seq1" do
+    diff_s2_s1 = Diff::LCS.diff(seq2, seq1)
     change_diff(correct_backward_diff).should == diff_s2_s1
   end
 
diff --git a/spec/diff_lcs_lcs_spec.rb b/spec/lcs_spec.rb
index c95ba61..c95ba61 100644
--- a/spec/diff_lcs_lcs_spec.rb
+++ b/spec/lcs_spec.rb
diff --git a/spec/diff_lcs_patch_spec.rb b/spec/patch_spec.rb
index 7e480e0..4be8b05 100644
--- a/spec/diff_lcs_patch_spec.rb
+++ b/spec/patch_spec.rb
@@ -5,196 +5,158 @@ require 'spec_helper'
 describe "Diff::LCS.patch" do
   include Diff::LCS::SpecHelper::Matchers
 
-  describe "using a Diff::LCS.diff patchset" do
-    describe "with default diff callbacks (DiffCallbacks)" do
-      before(:each) do
-        @patch_set_s1_s2 = Diff::LCS.diff(seq1, seq2)
-        @patch_set_s2_s1 = Diff::LCS.diff(seq2, seq1)
-      end
-
-      it "should correctly patch left-to-right (patch autodiscovery)" do
-        Diff::LCS.patch(seq1, @patch_set_s1_s2).should == seq2
-        Diff::LCS.patch(seq2, @patch_set_s2_s1).should == seq1
-      end
-
-      it "should correctly patch left-to-right (explicit patch)" do
-        Diff::LCS.patch(seq1, @patch_set_s1_s2, :patch).should == seq2
-        Diff::LCS.patch(seq2, @patch_set_s2_s1, :patch).should == seq1
-        Diff::LCS.patch!(seq1, @patch_set_s1_s2).should == seq2
-        Diff::LCS.patch!(seq2, @patch_set_s2_s1).should == seq1
-      end
-
-      it "should correctly patch right-to-left (unpatch autodiscovery)" do
-        Diff::LCS.patch(seq2, @patch_set_s1_s2).should == seq1
-        Diff::LCS.patch(seq1, @patch_set_s2_s1).should == seq2
-      end
+  shared_examples "patch sequences correctly" do
+    it "should correctly patch left-to-right (patch autodiscovery)" do
+      Diff::LCS.patch(s1, patch_set).should == s2
+    end
 
-      it "should correctly patch right-to-left (explicit unpatch)" do
-        Diff::LCS.patch(seq2, @patch_set_s1_s2, :unpatch).should == seq1
-        Diff::LCS.patch(seq1, @patch_set_s2_s1, :unpatch).should == seq2
-        Diff::LCS.unpatch!(seq2, @patch_set_s1_s2).should == seq1
-        Diff::LCS.unpatch!(seq1, @patch_set_s2_s1).should == seq2
-      end
+    it "should correctly patch left-to-right (explicit patch)" do
+      Diff::LCS.patch(s1, patch_set, :patch).should == s2
+      Diff::LCS.patch!(s1, patch_set).should == s2
     end
 
-    describe "with context diff callbacks (ContextDiffCallbacks)" do
-      before(:each) do
-        @patch_set_s1_s2 = Diff::LCS.diff(seq1, seq2, Diff::LCS::ContextDiffCallbacks)
-        @patch_set_s2_s1 = Diff::LCS.diff(seq2, seq1, Diff::LCS::ContextDiffCallbacks)
-      end
+    it "should correctly patch right-to-left (unpatch autodiscovery)" do
+      Diff::LCS.patch(s2, patch_set).should == s1
+    end
 
-      it "should correctly patch left-to-right (patch autodiscovery)" do
-        Diff::LCS.patch(seq1, @patch_set_s1_s2).should == seq2
-        Diff::LCS.patch(seq2, @patch_set_s2_s1).should == seq1
-      end
+    it "should correctly patch right-to-left (explicit unpatch)" do
+      Diff::LCS.patch(s2, patch_set, :unpatch).should == s1
+      Diff::LCS.unpatch!(s2, patch_set).should == s1
+    end
+  end
 
-      it "should correctly patch left-to-right (explicit patch)" do
-        Diff::LCS.patch(seq1, @patch_set_s1_s2, :patch).should == seq2
-        Diff::LCS.patch(seq2, @patch_set_s2_s1, :patch).should == seq1
-        Diff::LCS.patch!(seq1, @patch_set_s1_s2).should == seq2
-        Diff::LCS.patch!(seq2, @patch_set_s2_s1).should == seq1
+  describe "using a Diff::LCS.diff patchset" do
+    describe "with default diff callbacks (DiffCallbacks)" do
+      describe "forward (s1 -> s2)" do
+        it_should_behave_like "patch sequences correctly" do
+          let(:s1) { seq1 }
+          let(:s2) { seq2 }
+          let(:patch_set) { Diff::LCS.diff(seq1, seq2) }
+        end
       end
 
-      it "should correctly patch right-to-left (unpatch autodiscovery)" do
-        Diff::LCS.patch(seq2, @patch_set_s1_s2).should == seq1
-        Diff::LCS.patch(seq1, @patch_set_s2_s1).should == seq2
+      describe "reverse (s2 -> s1)" do
+        it_should_behave_like "patch sequences correctly" do
+          let(:s1) { seq2 }
+          let(:s2) { seq1 }
+          let(:patch_set) { Diff::LCS.diff(seq2, seq1) }
+        end
       end
+    end
 
-      it "should correctly patch right-to-left (explicit unpatch)" do
-        Diff::LCS.patch(seq2, @patch_set_s1_s2, :unpatch).should == seq1
-        Diff::LCS.patch(seq1, @patch_set_s2_s1, :unpatch).should == seq2
-        Diff::LCS.unpatch!(seq2, @patch_set_s1_s2).should == seq1
-        Diff::LCS.unpatch!(seq1, @patch_set_s2_s1).should == seq2
+    describe "with context diff callbacks (ContextDiffCallbacks)" do
+      describe "forward (s1 -> s2)" do
+        it_should_behave_like "patch sequences correctly" do
+          let(:s1) { seq1 }
+          let(:s2) { seq2 }
+          let(:patch_set) {
+            Diff::LCS.diff(seq1, seq2, Diff::LCS::ContextDiffCallbacks)
+          }
+        end
+      end
+
+      describe "reverse (s2 -> s1)" do
+        it_should_behave_like "patch sequences correctly" do
+          let(:s1) { seq2 }
+          let(:s2) { seq1 }
+          let(:patch_set) {
+            Diff::LCS.diff(seq2, seq1, Diff::LCS::ContextDiffCallbacks)
+          }
+        end
       end
     end
 
     describe "with sdiff callbacks (SDiffCallbacks)" do
-      before(:each) do
-        @patch_set_s1_s2 = Diff::LCS.diff(seq1, seq2, Diff::LCS::SDiffCallbacks)
-        @patch_set_s2_s1 = Diff::LCS.diff(seq2, seq1, Diff::LCS::SDiffCallbacks)
-      end
-
-      it "should correctly patch left-to-right (patch autodiscovery)" do
-        Diff::LCS.patch(seq1, @patch_set_s1_s2).should == seq2
-        Diff::LCS.patch(seq2, @patch_set_s2_s1).should == seq1
-      end
-
-      it "should correctly patch left-to-right (explicit patch)" do
-        Diff::LCS.patch(seq1, @patch_set_s1_s2, :patch).should == seq2
-        Diff::LCS.patch(seq2, @patch_set_s2_s1, :patch).should == seq1
-        Diff::LCS.patch!(seq1, @patch_set_s1_s2).should == seq2
-        Diff::LCS.patch!(seq2, @patch_set_s2_s1).should == seq1
-      end
-
-      it "should correctly patch right-to-left (unpatch autodiscovery)" do
-        Diff::LCS.patch(seq2, @patch_set_s1_s2).should == seq1
-        Diff::LCS.patch(seq1, @patch_set_s2_s1).should == seq2
-      end
-
-      it "should correctly patch right-to-left (explicit unpatch)" do
-        Diff::LCS.patch(seq2, @patch_set_s1_s2, :unpatch).should == seq1
-        Diff::LCS.patch(seq1, @patch_set_s2_s1, :unpatch).should == seq2
-        Diff::LCS.unpatch!(seq2, @patch_set_s1_s2).should == seq1
-        Diff::LCS.unpatch!(seq1, @patch_set_s2_s1).should == seq2
+      describe "forward (s1 -> s2)" do
+        it_should_behave_like "patch sequences correctly" do
+          let(:s1) { seq1 }
+          let(:s2) { seq2 }
+          let(:patch_set) {
+            Diff::LCS.diff(seq1, seq2, Diff::LCS::SDiffCallbacks)
+          }
+        end
+      end
+
+      describe "reverse (s2 -> s1)" do
+        it_should_behave_like "patch sequences correctly" do
+          let(:s1) { seq2 }
+          let(:s2) { seq1 }
+          let(:patch_set) {
+            Diff::LCS.diff(seq2, seq1, Diff::LCS::SDiffCallbacks)
+          }
+        end
       end
     end
   end
 
   describe "using a Diff::LCS.sdiff patchset" do
     describe "with default diff callbacks (DiffCallbacks)" do
-      before(:each) do
-        @patch_set_s1_s2 = Diff::LCS.sdiff(seq1, seq2, Diff::LCS::DiffCallbacks)
-        @patch_set_s2_s1 = Diff::LCS.sdiff(seq2, seq1, Diff::LCS::DiffCallbacks)
-      end
-
-      it "should correctly patch left-to-right (patch autodiscovery)" do
-        Diff::LCS.patch(seq1, @patch_set_s1_s2).should == seq2
-        Diff::LCS.patch(seq2, @patch_set_s2_s1).should == seq1
-      end
-
-      it "should correctly patch left-to-right (explicit patch)" do
-        Diff::LCS.patch(seq1, @patch_set_s1_s2, :patch).should == seq2
-        Diff::LCS.patch(seq2, @patch_set_s2_s1, :patch).should == seq1
-        Diff::LCS.patch!(seq1, @patch_set_s1_s2).should == seq2
-        Diff::LCS.patch!(seq2, @patch_set_s2_s1).should == seq1
-      end
-
-      it "should correctly patch right-to-left (unpatch autodiscovery)" do
-        Diff::LCS.patch(seq2, @patch_set_s1_s2).should == seq1
-        Diff::LCS.patch(seq1, @patch_set_s2_s1).should == seq2
-      end
-
-      it "should correctly patch right-to-left (explicit unpatch)" do
-        Diff::LCS.patch(seq2, @patch_set_s1_s2, :unpatch).should == seq1
-        Diff::LCS.patch(seq1, @patch_set_s2_s1, :unpatch).should == seq2
-        Diff::LCS.unpatch!(seq2, @patch_set_s1_s2).should == seq1
-        Diff::LCS.unpatch!(seq1, @patch_set_s2_s1).should == seq2
+      describe "forward (s1 -> s2)" do
+        it_should_behave_like "patch sequences correctly" do
+          let(:s1) { seq1 }
+          let(:s2) { seq2 }
+          let(:patch_set) {
+            Diff::LCS.sdiff(seq1, seq2, Diff::LCS::DiffCallbacks)
+          }
+        end
+      end
+
+      describe "reverse (s2 -> s1)" do
+        it_should_behave_like "patch sequences correctly" do
+          let(:s1) { seq2 }
+          let(:s2) { seq1 }
+          let(:patch_set) {
+            Diff::LCS.sdiff(seq2, seq1, Diff::LCS::DiffCallbacks)
+          }
+        end
       end
     end
 
-    describe "with context diff callbacks (ContextDiffCallbacks)" do
-      before(:each) do
-        @patch_set_s1_s2 = Diff::LCS.sdiff(seq1, seq2, Diff::LCS::ContextDiffCallbacks)
-        @patch_set_s2_s1 = Diff::LCS.sdiff(seq2, seq1, Diff::LCS::ContextDiffCallbacks)
-      end
-
-      it "should correctly patch left-to-right (patch autodiscovery)" do
-        Diff::LCS.patch(seq1, @patch_set_s1_s2).should == seq2
-        Diff::LCS.patch(seq2, @patch_set_s2_s1).should == seq1
-      end
-
-      it "should correctly patch left-to-right (explicit patch)" do
-        Diff::LCS.patch(seq1, @patch_set_s1_s2, :patch).should == seq2
-        Diff::LCS.patch(seq2, @patch_set_s2_s1, :patch).should == seq1
-        Diff::LCS.patch!(seq1, @patch_set_s1_s2).should == seq2
-        Diff::LCS.patch!(seq2, @patch_set_s2_s1).should == seq1
-      end
-
-      it "should correctly patch right-to-left (unpatch autodiscovery)" do
-        Diff::LCS.patch(seq2, @patch_set_s1_s2).should == seq1
-        Diff::LCS.patch(seq1, @patch_set_s2_s1).should == seq2
-      end
-
-      it "should correctly patch right-to-left (explicit unpatch)" do
-        Diff::LCS.patch(seq2, @patch_set_s1_s2, :unpatch).should == seq1
-        Diff::LCS.patch(seq1, @patch_set_s2_s1, :unpatch).should == seq2
-        Diff::LCS.unpatch!(seq2, @patch_set_s1_s2).should == seq1
-        Diff::LCS.unpatch!(seq1, @patch_set_s2_s1).should == seq2
+    describe "with context diff callbacks (DiffCallbacks)" do
+      describe "forward (s1 -> s2)" do
+        it_should_behave_like "patch sequences correctly" do
+          let(:s1) { seq1 }
+          let(:s2) { seq2 }
+          let(:patch_set) {
+            Diff::LCS.sdiff(seq1, seq2, Diff::LCS::ContextDiffCallbacks)
+          }
+        end
+      end
+
+      describe "reverse (s2 -> s1)" do
+        it_should_behave_like "patch sequences correctly" do
+          let(:s1) { seq2 }
+          let(:s2) { seq1 }
+          let(:patch_set) {
+            Diff::LCS.sdiff(seq2, seq1, Diff::LCS::ContextDiffCallbacks)
+          }
+        end
       end
     end
 
-    describe "with sdiff callbacks" do
-      before(:each) do
-        @patch_set_s1_s2 = Diff::LCS.sdiff(seq1, seq2)
-        @patch_set_s2_s1 = Diff::LCS.sdiff(seq2, seq1)
-      end
-
-      it "should correctly patch left-to-right (patch autodiscovery)" do
-        Diff::LCS.patch(seq1, @patch_set_s1_s2).should == seq2
-        Diff::LCS.patch(seq2, @patch_set_s2_s1).should == seq1
-      end
-
-      it "should correctly patch left-to-right (explicit patch)" do
-        Diff::LCS.patch(seq1, @patch_set_s1_s2, :patch).should == seq2
-        Diff::LCS.patch(seq2, @patch_set_s2_s1, :patch).should == seq1
-        Diff::LCS.patch!(seq1, @patch_set_s1_s2).should == seq2
-        Diff::LCS.patch!(seq2, @patch_set_s2_s1).should == seq1
-      end
-
-      it "should correctly patch right-to-left (unpatch autodiscovery)" do
-        Diff::LCS.patch(seq2, @patch_set_s1_s2).should == seq1
-        Diff::LCS.patch(seq1, @patch_set_s2_s1).should == seq2
+    describe "with sdiff callbacks (SDiffCallbacks)" do
+      describe "forward (s1 -> s2)" do
+        it_should_behave_like "patch sequences correctly" do
+          let(:s1) { seq1 }
+          let(:s2) { seq2 }
+          let(:patch_set) { Diff::LCS.sdiff(seq1, seq2) }
+        end
       end
 
-      it "should correctly patch right-to-left (explicit unpatch)" do
-        Diff::LCS.patch(seq2, @patch_set_s1_s2, :unpatch).should == seq1
-        Diff::LCS.patch(seq1, @patch_set_s2_s1, :unpatch).should == seq2
-        Diff::LCS.unpatch!(seq2, @patch_set_s1_s2).should == seq1
-        Diff::LCS.unpatch!(seq1, @patch_set_s2_s1).should == seq2
+      describe "reverse (s2 -> s1)" do
+        it_should_behave_like "patch sequences correctly" do
+          let(:s1) { seq2 }
+          let(:s2) { seq1 }
+          let(:patch_set) { Diff::LCS.sdiff(seq2, seq1) }
+        end
       end
     end
   end
 
+  # Note: because of the error in autodiscovery ("does not autodiscover s1
+  # to s2 patches"), this cannot use the "patch sequences correctly" shared
+  # set. Once the bug in autodiscovery is fixed, this can be converted as
+  # above.
   describe "fix bug 891: patchsets do not contain the last equal part" do
     before(:each) do
       @s1 = %w(a b c d   e f g h i j k)
@@ -386,7 +348,7 @@ describe "Diff::LCS.patch" do
       end
     end
 
-    describe "using Diff::LCS.xdiff with default diff callbacks" do
+    describe "using Diff::LCS.sdiff with default diff callbacks" do
       before(:each) do
         @patch_set_s1_s2 = Diff::LCS.sdiff(@s1, @s2, Diff::LCS::DiffCallbacks)
         @patch_set_s2_s1 = Diff::LCS.sdiff(@s2, @s1, Diff::LCS::DiffCallbacks)
diff --git a/spec/sdiff_spec.rb b/spec/sdiff_spec.rb
new file mode 100644
index 0000000..f174c35
--- /dev/null
+++ b/spec/sdiff_spec.rb
@@ -0,0 +1,204 @@
+# -*- ruby encoding: utf-8 -*-
+
+require 'spec_helper'
+
+describe "Diff::LCS.sdiff" do
+  include Diff::LCS::SpecHelper::Matchers
+
+  shared_examples "compare sequences correctly" do
+    it "should compare s1 -> s2 correctly" do
+      Diff::LCS.sdiff(s1, s2).should == context_diff(result)
+    end
+
+    it "should compare s2 -> s1 correctly" do
+      Diff::LCS.sdiff(s2, s1).should == context_diff(reverse_sdiff(result))
+    end
+  end
+
+  describe "using seq1 & seq2" do
+    let(:s1) { seq1 }
+    let(:s2) { seq2 }
+    let(:result) { correct_forward_sdiff }
+
+    it_should_behave_like "compare sequences correctly"
+  end
+
+  describe "using %w(abc def yyy xxx ghi jkl) & %w(abc dxf xxx ghi jkl)" do
+    let(:s1) { %w(abc def yyy xxx ghi jkl) }
+    let(:s2) { %w(abc dxf xxx ghi jkl) }
+    let(:result) {
+      [
+        [ '=', [ 0, 'abc' ], [ 0, 'abc' ] ],
+        [ '!', [ 1, 'def' ], [ 1, 'dxf' ] ],
+        [ '-', [ 2, 'yyy' ], [ 2,  nil  ] ],
+        [ '=', [ 3, 'xxx' ], [ 2, 'xxx' ] ],
+        [ '=', [ 4, 'ghi' ], [ 3, 'ghi' ] ],
+        [ '=', [ 5, 'jkl' ], [ 4, 'jkl' ] ]
+      ]
+    }
+
+    it_should_behave_like "compare sequences correctly"
+  end
+
+  describe "using %w(a b c d e) & %w(a e)" do
+    let(:s1) { %w(a b c d e) }
+    let(:s2) { %w(a e) }
+    let(:result) {
+      [
+        [ '=', [ 0, 'a' ], [ 0, 'a' ] ],
+        [ '-', [ 1, 'b' ], [ 1, nil ] ],
+        [ '-', [ 2, 'c' ], [ 1, nil ] ],
+        [ '-', [ 3, 'd' ], [ 1, nil ] ],
+        [ '=', [ 4, 'e' ], [ 1, 'e' ] ]
+      ]
+    }
+
+    it_should_behave_like "compare sequences correctly"
+  end
+
+  describe "using %w(a e) & %w(a b c d e)" do
+    let(:s1) { %w(a e) }
+    let(:s2) { %w(a b c d e) }
+    let(:result) {
+      [
+        [ '=', [ 0, 'a' ], [ 0, 'a' ] ],
+        [ '+', [ 1, nil ], [ 1, 'b' ] ],
+        [ '+', [ 1, nil ], [ 2, 'c' ] ],
+        [ '+', [ 1, nil ], [ 3, 'd' ] ],
+        [ '=', [ 1, 'e' ], [ 4, 'e' ] ]
+      ]
+    }
+
+    it_should_behave_like "compare sequences correctly"
+  end
+
+  describe "using %w(v x a e) & %w(w y a b c d e)" do
+    let(:s1) { %w(v x a e) }
+    let(:s2) { %w(w y a b c d e) }
+    let(:result) {
+      [
+        [ '!', [ 0, 'v' ], [ 0, 'w' ] ],
+        [ '!', [ 1, 'x' ], [ 1, 'y' ] ],
+        [ '=', [ 2, 'a' ], [ 2, 'a' ] ],
+        [ '+', [ 3, nil ], [ 3, 'b' ] ],
+        [ '+', [ 3, nil ], [ 4, 'c' ] ],
+        [ '+', [ 3, nil ], [ 5, 'd' ] ],
+        [ '=', [ 3, 'e' ], [ 6, 'e' ] ]
+      ]
+    }
+
+    it_should_behave_like "compare sequences correctly"
+  end
+
+  describe "using %w(x a e) & %w(a b c d e)" do
+    let(:s1) { %w(x a e) }
+    let(:s2) { %w(a b c d e) }
+    let(:result) {
+      [
+        [ '-', [ 0, 'x' ], [ 0, nil ] ],
+        [ '=', [ 1, 'a' ], [ 0, 'a' ] ],
+        [ '+', [ 2, nil ], [ 1, 'b' ] ],
+        [ '+', [ 2, nil ], [ 2, 'c' ] ],
+        [ '+', [ 2, nil ], [ 3, 'd' ] ],
+        [ '=', [ 2, 'e' ], [ 4, 'e' ] ]
+      ]
+    }
+
+    it_should_behave_like "compare sequences correctly"
+  end
+
+  describe "using %w(a e) & %w(x a b c d e)" do
+    let(:s1) { %w(a e) }
+    let(:s2) { %w(x a b c d e) }
+    let(:result) {
+      [
+        [ '+', [ 0, nil ], [ 0, 'x' ] ],
+        [ '=', [ 0, 'a' ], [ 1, 'a' ] ],
+        [ '+', [ 1, nil ], [ 2, 'b' ] ],
+        [ '+', [ 1, nil ], [ 3, 'c' ] ],
+        [ '+', [ 1, nil ], [ 4, 'd' ] ],
+        [ '=', [ 1, 'e' ], [ 5, 'e' ] ]
+      ]
+    }
+
+    it_should_behave_like "compare sequences correctly"
+  end
+
+  describe "using %w(a e v) & %w(x a b c d e w x)" do
+    let(:s1) { %w(a e v) }
+    let(:s2) { %w(x a b c d e w x) }
+    let(:result) {
+      [
+        [ '+', [ 0, nil ], [ 0, 'x' ] ],
+        [ '=', [ 0, 'a' ], [ 1, 'a' ] ],
+        [ '+', [ 1, nil ], [ 2, 'b' ] ],
+        [ '+', [ 1, nil ], [ 3, 'c' ] ],
+        [ '+', [ 1, nil ], [ 4, 'd' ] ],
+        [ '=', [ 1, 'e' ], [ 5, 'e' ] ],
+        [ '!', [ 2, 'v' ], [ 6, 'w' ] ],
+        [ '+', [ 3, nil ], [ 7, 'x' ] ]
+      ]
+    }
+
+    it_should_behave_like "compare sequences correctly"
+  end
+
+  describe "using %w() & %w(a b c)" do
+    let(:s1) { %w() }
+    let(:s2) { %w(a b c) }
+    let(:result) {
+      [
+        [ '+', [ 0, nil ], [ 0, 'a' ] ],
+        [ '+', [ 0, nil ], [ 1, 'b' ] ],
+        [ '+', [ 0, nil ], [ 2, 'c' ] ]
+      ]
+    }
+
+    it_should_behave_like "compare sequences correctly"
+  end
+
+  describe "using %w(a b c) & %w(1)" do
+    let(:s1) { %w(a b c) }
+    let(:s2) { %w(1) }
+    let(:result) {
+      [
+        [ '!', [ 0, 'a' ], [ 0, '1' ] ],
+        [ '-', [ 1, 'b' ], [ 1, nil ] ],
+        [ '-', [ 2, 'c' ], [ 1, nil ] ]
+      ]
+    }
+
+    it_should_behave_like "compare sequences correctly"
+  end
+
+  describe "using %w(a b c) & %w(c)" do
+    let(:s1) { %w(a b c) }
+    let(:s2) { %w(c) }
+    let(:result) {
+      [
+        [ '-', [ 0, 'a' ], [ 0, nil ] ],
+        [ '-', [ 1, 'b' ], [ 0, nil ] ],
+        [ '=', [ 2, 'c' ], [ 0, 'c' ] ]
+      ]
+    }
+
+    it_should_behave_like "compare sequences correctly"
+  end
+
+  describe "using %w(abcd efgh ijkl mnop) & []" do
+    let(:s1) { %w(abcd efgh ijkl mnop) }
+    let(:s2) { [] }
+    let(:result) {
+      [
+        [ '-', [ 0, 'abcd' ], [ 0, nil ] ],
+        [ '-', [ 1, 'efgh' ], [ 0, nil ] ],
+        [ '-', [ 2, 'ijkl' ], [ 0, nil ] ],
+        [ '-', [ 3, 'mnop' ], [ 0, nil ] ]
+      ]
+    }
+
+    it_should_behave_like "compare sequences correctly"
+  end
+end
+
+# vim: ft=ruby
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 5150b10..60ee9e9 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,8 +1,6 @@
 # -*- ruby encoding: utf-8 -*-
 
 require 'rubygems'
-require 'bundler'
-
 require 'pathname'
 
 file   = Pathname.new(__FILE__).expand_path
diff --git a/spec/diff_lcs_balanced_spec.rb b/spec/traverse_balanced_spec.rb
index 1e03c5d..1e03c5d 100644
--- a/spec/diff_lcs_balanced_spec.rb
+++ b/spec/traverse_balanced_spec.rb
diff --git a/spec/diff_lcs_sequences_spec.rb b/spec/traverse_sequences_spec.rb
index c7a5558..c7a5558 100644
--- a/spec/diff_lcs_sequences_spec.rb
+++ b/spec/traverse_sequences_spec.rb