Expanding rspec tests to reflect reality.

There's a lot more testing that was happening in the code than was being
reported. Now many of the special cases that were hidden by the
transforms for balanced traversal (reverse, change/no change) have been
made into individual tests with the use of shared example groups.

2 files changed, 226 insertions, 94 deletions

diff --git a/spec/diff_lcs_balanced_spec.rb b/spec/diff_lcs_balanced_spec.rb
index 36e11c9..1e03c5d 100644
--- a/spec/diff_lcs_balanced_spec.rb
+++ b/spec/diff_lcs_balanced_spec.rb
@@ -2,58 +2,34 @@
 
 require 'spec_helper'
 
-describe "Diff::LCS.traverse_balanced should traverse sequences correctly" do
+describe "Diff::LCS.traverse_balanced" do
   include Diff::LCS::SpecHelper::Matchers
 
-  def reverse(change_result)
-    new_result = []
-    change_result.each { |line|
-      line = [ line[0], line[2], line[1] ]
-      case line[0]
-      when '<'
-        line[0] = '>'
-      when '>'
-        line[0] = '<'
-      end
-      new_result << line
-    }
-    new_result.sort_by { |line| line[1] }
-  end
-
-  def no_change(change_result)
-    new_result = []
-    change_result.each { |line|
-      case line[0]
-      when '!'
-        new_result << [ '<', line[1], line[2] ]
-        new_result << [ '>', line[1] + 1, line[2] ]
-      else
-        new_result << line
-      end
-    }
-    new_result
-  end
-
-  def traverse(s1, s2, callback_type)
-    callback = __send__(callback_type)
-    Diff::LCS.traverse_balanced(s1, s2, callback)
-    callback
-  end
-
-  def do_balanced_traversal(s1, s2, result)
-    balanced_s1_s2 = traverse(s1, s2, :balanced_callback)
-    balanced_s2_s1 = traverse(s2, s1, :balanced_callback)
-    balanced_s1_s2_no_change = traverse(s1, s2, :balanced_callback_no_change)
-    balanced_s2_s1_no_change = traverse(s2, s1, :balanced_callback_no_change)
-
-    balanced_s1_s2.result.should == result
-    balanced_s2_s1.result.should == reverse(result)
-
-    balanced_s1_s2_no_change.result.should == no_change(result)
-    balanced_s2_s1_no_change.result.should == no_change(reverse(result))
-  end
-
-  it "sequence-a" do
+  shared_examples "with a #change callback" do |s1, s2, result|
+    it "should traverse s1 -> s2 correctly" do
+      traversal = balanced_traversal(s1, s2, :balanced_callback)
+      traversal.result.should == result
+    end
+
+    it "should traverse s2 -> s1 correctly" do
+      traversal = balanced_traversal(s2, s1, :balanced_callback)
+      traversal.result.should == balanced_reverse(result)
+    end
+  end
+
+  shared_examples "without a #change callback" do |s1, s2, result|
+    it "should traverse s1 -> s2 correctly" do
+      traversal = balanced_traversal(s1, s2, :balanced_callback_no_change)
+      traversal.result.should == map_to_no_change(result)
+    end
+
+    it "should traverse s2 -> s1 correctly" do
+      traversal = balanced_traversal(s2, s1, :balanced_callback_no_change)
+      traversal.result.should == map_to_no_change(balanced_reverse(result))
+    end
+  end
+
+  describe "sequences %w(a b c) & %w(a x c)" do
     s1 = %w(a b c)
     s2 = %w(a x c)
 
@@ -63,10 +39,11 @@ describe "Diff::LCS.traverse_balanced should traverse sequences correctly" do
       [ '=', 2, 2 ]
     ]
 
-    do_balanced_traversal(s1, s2, result)
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
   end
 
-  it "sequence-b" do
+  describe "sequences %w(a x y c) & %w(a v w c)" do
     s1 = %w(a x y c)
     s2 = %w(a v w c)
 
@@ -77,10 +54,11 @@ describe "Diff::LCS.traverse_balanced should traverse sequences correctly" do
       [ '=', 3, 3 ]
     ]
 
-    do_balanced_traversal(s1, s2, result)
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
   end
 
-  it "sequence-c" do
+  describe "sequences %w(x y c) & %w(v w c)" do
     s1 = %w(x y c)
     s2 = %w(v w c)
     result = [
@@ -89,10 +67,11 @@ describe "Diff::LCS.traverse_balanced should traverse sequences correctly" do
       [ '=', 2, 2 ]
     ]
 
-    do_balanced_traversal(s1, s2, result)
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
   end
 
-  it "sequence-d" do
+  describe "sequences %w(a x y z) & %w(b v w)" do
     s1 = %w(a x y z)
     s2 = %w(b v w)
     result = [
@@ -102,10 +81,11 @@ describe "Diff::LCS.traverse_balanced should traverse sequences correctly" do
       [ '<', 3, 3 ]
     ]
 
-    do_balanced_traversal(s1, s2, result)
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
   end
 
-  it "sequence-e" do
+  describe "sequences %w(a z) & %w(a)" do
     s1 = %w(a z)
     s2 = %w(a)
     result = [
@@ -113,10 +93,11 @@ describe "Diff::LCS.traverse_balanced should traverse sequences correctly" do
       [ '<', 1, 1 ]
     ]
 
-    do_balanced_traversal(s1, s2, result)
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
   end
 
-  it "sequence-f" do
+  describe "sequences %w(z a) & %w(a)" do
     s1 = %w(z a)
     s2 = %w(a)
     result = [
@@ -124,10 +105,11 @@ describe "Diff::LCS.traverse_balanced should traverse sequences correctly" do
       [ '=', 1, 0 ]
     ]
 
-    do_balanced_traversal(s1, s2, result)
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
   end
 
-  it "sequence-g" do
+  describe "sequences %w(a b c) & %w(x y z)" do
     s1 = %w(a b c)
     s2 = %w(x y z)
     result = [
@@ -136,10 +118,11 @@ describe "Diff::LCS.traverse_balanced should traverse sequences correctly" do
       [ '!', 2, 2 ]
     ]
 
-    do_balanced_traversal(s1, s2, result)
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
   end
 
-  it "sequence-h" do
+  describe "sequences %w(abcd efgh ijkl mnoopqrstuvwxyz) & []" do
     s1 = %w(abcd efgh ijkl mnopqrstuvwxyz)
     s2 = []
     result = [
@@ -149,20 +132,154 @@ describe "Diff::LCS.traverse_balanced should traverse sequences correctly" do
       [ '<', 3, 0 ]
     ]
 
-    do_balanced_traversal(s1, s2, result)
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
+  end
+
+  describe "strings %Q(a b c) & %Q(a x c)" do
+    s1 = %Q(a b c)
+    s2 = %Q(a x c)
+
+    result = [
+      [ '=', 0, 0 ],
+      [ '=', 1, 1 ],
+      [ '!', 2, 2 ],
+      [ '=', 3, 3 ],
+      [ '=', 4, 4 ]
+    ]
+
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
+  end
+
+  describe "strings %Q(a x y c) & %Q(a v w c)" do
+    s1 = %Q(a x y c)
+    s2 = %Q(a v w c)
+
+    result = [
+      [ '=', 0, 0 ],
+      [ '=', 1, 1 ],
+      [ '!', 2, 2 ],
+      [ '=', 3, 3 ],
+      [ '!', 4, 4 ],
+      [ '=', 5, 5 ],
+      [ '=', 6, 6 ]
+    ]
+
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
+  end
+
+  describe "strings %Q(x y c) & %Q(v w c)" do
+    s1 = %Q(x y c)
+    s2 = %Q(v w c)
+    result = [
+      [ '!', 0, 0 ],
+      [ '=', 1, 1 ],
+      [ '!', 2, 2 ],
+      [ '=', 3, 3 ],
+      [ '=', 4, 4 ]
+    ]
+
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
+  end
+
+  describe "strings %Q(a x y z) & %Q(b v w)" do
+    s1 = %Q(a x y z)
+    s2 = %Q(b v w)
+    result = [
+      [ '!', 0, 0 ],
+      [ '=', 1, 1 ],
+      [ '!', 2, 2 ],
+      [ '=', 3, 3 ],
+      [ '!', 4, 4 ],
+      [ '<', 5, 5 ],
+      [ '<', 6, 5 ]
+    ]
+
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
+  end
+
+  describe "strings %Q(a z) & %Q(a)" do
+    s1 = %Q(a z)
+    s2 = %Q(a)
+    result = [
+      [ '=', 0, 0 ],
+      [ '<', 1, 1 ],
+      [ '<', 2, 1 ]
+    ]
+
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
+  end
+
+  describe "strings %Q(z a) & %Q(a)" do
+    s1 = %Q(z a)
+    s2 = %Q(a)
+    result = [
+      [ '<', 0, 0 ],
+      [ '<', 1, 0 ],
+      [ '=', 2, 0 ]
+    ]
+
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
+  end
+
+  describe "strings %Q(a b c) & %Q(x y z)" do
+    s1 = %Q(a b c)
+    s2 = %Q(x y z)
+    result = [
+      [ '!', 0, 0 ],
+      [ '=', 1, 1 ],
+      [ '!', 2, 2 ],
+      [ '=', 3, 3 ],
+      [ '!', 4, 4 ]
+    ]
+
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
   end
 
-  it "sequence-i" do
-    s1 = []
-    s2 = %w(abcd efgh ijkl mnopqrstuvwxyz)
+  describe "strings %Q(abcd efgh ijkl mnopqrstuvwxyz) & %Q()" do
+    s1 = %Q(abcd efgh ijkl mnopqrstuvwxyz)
+    s2 = ""
     result = [
-      [ '>', 0, 0 ],
-      [ '>', 0, 1 ],
-      [ '>', 0, 2 ],
-      [ '>', 0, 3 ]
+      [ '<',  0, 0 ],
+      [ '<',  1, 0 ],
+      [ '<',  2, 0 ],
+      [ '<',  3, 0 ],
+      [ '<',  4, 0 ],
+      [ '<',  5, 0 ],
+      [ '<',  6, 0 ],
+      [ '<',  7, 0 ],
+      [ '<',  8, 0 ],
+      [ '<',  9, 0 ],
+      [ '<', 10, 0 ],
+      [ '<', 11, 0 ],
+      [ '<', 12, 0 ],
+      [ '<', 13, 0 ],
+      [ '<', 14, 0 ],
+      [ '<', 15, 0 ],
+      [ '<', 16, 0 ],
+      [ '<', 17, 0 ],
+      [ '<', 18, 0 ],
+      [ '<', 19, 0 ],
+      [ '<', 20, 0 ],
+      [ '<', 21, 0 ],
+      [ '<', 22, 0 ],
+      [ '<', 23, 0 ],
+      [ '<', 24, 0 ],
+      [ '<', 25, 0 ],
+      [ '<', 26, 0 ],
+      [ '<', 27, 0 ],
+      [ '<', 28, 0 ],
     ]
 
-    do_balanced_traversal(s1, s2, result)
+    it_should_behave_like "with a #change callback", s1, s2, result
+    it_should_behave_like "without a #change callback", s1, s2, result
   end
 end
 
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 1c934e7..5150b10 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -126,6 +126,42 @@ module Diff::LCS::SpecHelper
     end
   end
 
+  def balanced_traversal(s1, s2, callback_type)
+    callback = __send__(callback_type)
+    Diff::LCS.traverse_balanced(s1, s2, callback)
+    callback
+  end
+
+  def balanced_reverse(change_result)
+    new_result = []
+    change_result.each { |line|
+      line = [ line[0], line[2], line[1] ]
+      case line[0]
+      when '<'
+        line[0] = '>'
+      when '>'
+        line[0] = '<'
+      end
+      new_result << line
+    }
+    new_result.sort_by { |line| line[1] }
+  end
+
+  def map_to_no_change(change_result)
+    new_result = []
+    change_result.each { |line|
+      case line[0]
+      when '!'
+        new_result << [ '<', line[1], line[2] ]
+        new_result << [ '>', line[1] + 1, line[2] ]
+      else
+        new_result << line
+      end
+    }
+    new_result
+  end
+
+
   def simple_callback
     callbacks = Object.new
     class << callbacks
@@ -246,25 +282,4 @@ RSpec.configure do |conf|
   conf.include Diff::LCS::SpecHelper
 end
 
-
-=begin
-RSpec::Matchers.define :be_a_multiple_of do |expected|
-  match do |actual|
-    actual % expected == 0
-  end
-
-  failure_message_for_should do |actual|
-    "expected that #{actual} would be a multiple of #{expected}"
-  end
-
-  failure_message_for_should_not do |actual|
-    "expected that #{actual} would not be a multiple of #{expected}"
-  end
-
-  description do
-    "be multiple of #{expected}"
-  end
-end
-=end
-
 # vim: ft=ruby