Resolve ldiff output issues

Resolves #5 and #6 by adding system-output comparison calls to `bin/ldiff`
compared against some pre-generated output.

History.md

@@ -6,6 +6,9 @@
     implicitly treated arrays. Originally provided as pull request [#47][],
     but it introduced a number of test failures as documented in [#48][], and
     remediation of Diff::LCS itself was introduced in [#49][].
+*   Resolved [#5][] with some tests comparing output from `system` calls to
+    `bin/ldiff` with some pre-generated output. Resolved [#6][] with these
+    tests.
 
 ## 1.3 / 2017-01-18
 
@@ -212,6 +215,8 @@
 [#2]: https://github.com/halostatue/diff-lcs/issues/2
 [#3]: https://github.com/halostatue/diff-lcs/issues/3
 [#4]: https://github.com/halostatue/diff-lcs/issues/4
+[#5]: https://github.com/halostatue/diff-lcs/issues/5
+[#6]: https://github.com/halostatue/diff-lcs/issues/6
 [#8]: https://github.com/halostatue/diff-lcs/pull/8
 [#9]: https://github.com/halostatue/diff-lcs/pull/9
 [#10]: https://github.com/halostatue/diff-lcs/pull/10

lib/diff/lcs/hunk.rb

@@ -20,6 +20,7 @@ def initialize(data_old, data_new, piece, flag_context, file_length_difference)
     before = after = file_length_difference
     after += @blocks[0].diff_size
     @file_length_difference = after # The caller must get this manually
+    @max_diff_size = @blocks.lazy.map { |e| e.diff_size }.max
 
     # Save the start & end of each array. If the array doesn't exist (e.g.,
     # we're only adding items in this block), then figure out the line
@@ -70,6 +71,8 @@ def flag_context=(context) #:nodoc: # rubocop:disable Lint/DuplicateMethods
         context
       end
 
+    add_end = @max_diff_size if add_end > @max_diff_size
+
     @end_old += add_end
     @end_new += add_end
   end

lib/diff/lcs/ldiff.rb

@@ -134,9 +134,9 @@ def run(args, _input = $stdin, output = $stdout, error = $stderr) #:nodoc:
     end
 
     if (@format == :unified) or (@format == :context)
-      ft = File.stat(file_old).mtime.localtime.strftime('%Y-%m-%d %H:%M:%S.%N %z')
+      ft = File.stat(file_old).mtime.localtime.strftime('%Y-%m-%d %H:%M:%S.000000000 %z')
       output << "#{char_old} #{file_old}\t#{ft}\n"
-      ft = File.stat(file_new).mtime.localtime.strftime('%Y-%m-%d %H:%M:%S.%N %z')
+      ft = File.stat(file_new).mtime.localtime.strftime('%Y-%m-%d %H:%M:%S.000000000 %z')
       output << "#{char_new} #{file_new}\t#{ft}\n"
     end
 
@@ -163,7 +163,10 @@ def run(args, _input = $stdin, output = $stdout, error = $stderr) #:nodoc:
       end
     end
 
-    output << oldhunk.diff(@format) << "\n"
+    last = oldhunk.diff(@format)
+    last << "\n" if last.respond_to?(:end_with?) && !last.end_with?("\n")
+
+    output << last
 
     output.reverse_each { |e| real_output << e.diff(:ed_finish) } if @format == :ed
 

spec/fixtures/aX

@@ -0,0 +1 @@
+aX

spec/fixtures/bXaX

@@ -0,0 +1 @@
+bXaX

spec/fixtures/ldiff/output.diff

@@ -0,0 +1,4 @@
+1c1
+< aX
+---
+> bXaX

spec/fixtures/ldiff/output.diff-c

@@ -0,0 +1,7 @@
+*** spec/fixtures/aX	2019-02-01 22:29:34.000000000 -0500
+--- spec/fixtures/bXaX	2019-02-01 22:29:43.000000000 -0500
+***************
+*** 1 ****
+! aX
+--- 1 ----
+! bXaX

spec/fixtures/ldiff/output.diff-e

@@ -0,0 +1,3 @@
+1c
+bXaX
+.

spec/fixtures/ldiff/output.diff-f

@@ -0,0 +1,3 @@
+c1
+bXaX
+.

spec/fixtures/ldiff/output.diff-u

@@ -0,0 +1,5 @@
+--- spec/fixtures/aX	2019-02-01 22:29:34.000000000 -0500
++++ spec/fixtures/bXaX	2019-02-01 22:29:43.000000000 -0500
+@@ -1 +1 @@
+-aX
++bXaX

spec/hunk_spec.rb

@@ -13,7 +13,7 @@
 
     it 'produces a unified diff from the two pieces' do
       expected = <<-EXPECTED.gsub(/^\s+/, '').encode('UTF-16LE').chomp
-        @@ -1,2 +1,2 @@
+        @@ -1 +1 @@
         -Tu avec carté {count} itém has
         +Tu avec carte {count} item has
       EXPECTED
@@ -24,18 +24,18 @@
     it 'produces a context diff from the two pieces' do
       expected = <<-EXPECTED.gsub(/^\s+/, '').encode('UTF-16LE').chomp
         ***************
-        *** 1,2 ****
-        !Tu avec carté {count} itém has
-        --- 1,2 ----
-        !Tu avec carte {count} item has
+        *** 1 ****
+        ! Tu avec carté {count} itém has
+        --- 1 ----
+        ! Tu avec carte {count} item has
       EXPECTED
 
       expect(hunk.diff(:context)).to eq(expected)
     end
 
     it 'produces an old diff from the two pieces' do
       expected = <<-EXPECTED.gsub(/^ +/, '').encode('UTF-16LE').chomp
-        1,2c1,2
+        1c1
         < Tu avec carté {count} itém has
         ---
         > Tu avec carte {count} item has
@@ -47,7 +47,7 @@
 
     it 'produces a reverse ed diff from the two pieces' do
       expected = <<-EXPECTED.gsub(/^ +/, '').encode('UTF-16LE').chomp
-        c1,2
+        c1
         Tu avec carte {count} item has
         .
 

spec/ldiff_spec.rb

@@ -2,50 +2,40 @@
 
 require 'spec_helper'
 
-describe 'Diff::LCS.diff' do
-  include Diff::LCS::SpecHelper::Matchers
-
-  it 'correctly diffs seq1 to seq2' do
-    diff_s1_s2 = Diff::LCS.diff(seq1, seq2)
-    expect(change_diff(correct_forward_diff)).to eq(diff_s1_s2)
-  end
-
-  it 'correctly diffs seq2 to seq1' do
-    diff_s2_s1 = Diff::LCS.diff(seq2, seq1)
-    expect(change_diff(correct_backward_diff)).to eq(diff_s2_s1)
+RSpec.describe 'bin/ldiff' do
+  let(:output_diff) { IO.binread('spec/fixtures/ldiff/output.diff') }
+  let(:output_diff_c) { IO.binread('spec/fixtures/ldiff/output.diff-c') }
+  let(:output_diff_e) { IO.binread('spec/fixtures/ldiff/output.diff-e') }
+  let(:output_diff_f) { IO.binread('spec/fixtures/ldiff/output.diff-f') }
+  let(:output_diff_u) { IO.binread('spec/fixtures/ldiff/output.diff-u') }
+
+  specify do
+    expect {
+      system 'ruby -Ilib bin/ldiff spec/fixtures/aX spec/fixtures/bXaX'
+    }.to output(output_diff).to_stdout_from_any_process
   end
 
-  it 'correctly diffs against an empty sequence' do
-    diff = Diff::LCS.diff(word_sequence, [])
-    correct_diff = [
-      [
-        ['-', 0, 'abcd'],
-        ['-', 1, 'efgh'],
-        ['-', 2, 'ijkl'],
-        ['-', 3, 'mnopqrstuvwxyz']
-      ]
-    ]
-
-    expect(change_diff(correct_diff)).to eq(diff)
-
-    diff = Diff::LCS.diff([], word_sequence)
-    correct_diff.each do |hunk|
-      hunk.each do |change| change[0] = '+' end
-    end
-    expect(change_diff(correct_diff)).to eq(diff)
+  specify do
+    expect {
+      system 'ruby -Ilib bin/ldiff -c spec/fixtures/aX spec/fixtures/bXaX'
+    }.to output(output_diff_c).to_stdout_from_any_process
   end
 
-  it "correctly diffs 'xx' and 'xaxb'" do
-    left = 'xx'
-    right = 'xaxb'
-    expect(Diff::LCS.patch(left, Diff::LCS.diff(left, right))).to eq(right)
+  specify do
+    expect {
+      system 'ruby -Ilib bin/ldiff -e spec/fixtures/aX spec/fixtures/bXaX'
+    }.to output(output_diff_e).to_stdout_from_any_process
   end
 
-  it 'returns an empty diff with (hello, hello)' do
-    expect(Diff::LCS.diff(hello, hello)).to eq([])
+  specify do
+    expect {
+      system 'ruby -Ilib bin/ldiff -f spec/fixtures/aX spec/fixtures/bXaX'
+    }.to output(output_diff_f).to_stdout_from_any_process
   end
 
-  it 'returns an empty diff with (hello_ary, hello_ary)' do
-    expect(Diff::LCS.diff(hello_ary, hello_ary)).to eq([])
+  specify do
+    expect {
+      system 'ruby -Ilib bin/ldiff -u spec/fixtures/aX spec/fixtures/bXaX'
+    }.to output(output_diff_u).to_stdout_from_any_process
   end
 end