Merge pull request #17 from JonRowe/guard_against_empty

Fix an issue caused by detecting the encoding when first data is empty

2 files changed, 38 insertions, 29 deletions

diff --git a/lib/diff/lcs/hunk.rb b/lib/diff/lcs/hunk.rb
index 6c5ea6a..05c3fb6 100644
--- a/lib/diff/lcs/hunk.rb
+++ b/lib/diff/lcs/hunk.rb
@@ -12,7 +12,7 @@ class Diff::LCS::Hunk
     # At first, a hunk will have just one Block in it
     @blocks = [ Diff::LCS::Block.new(piece) ]
     if String.method_defined?(:encoding)
-      @preferred_data_encoding = data_old[0].encoding
+      @preferred_data_encoding = data_old.fetch(0, data_new.fetch(0,'') ).encoding
     end
     @data_old = data_old
     @data_new = data_new
diff --git a/spec/hunk_spec.rb b/spec/hunk_spec.rb
index 0741b87..dc6f532 100644
--- a/spec/hunk_spec.rb
+++ b/spec/hunk_spec.rb
@@ -15,49 +15,58 @@ describe "Diff::LCS::Hunk" do
     let(:hunk)     { Diff::LCS::Hunk.new(old_data, new_data, pieces[0], 3, 0) }
 
     it 'should be able to produce a unified diff from the two pieces' do
-      expected =
-(<<-EOD.encode('UTF-16LE').chomp)
-@@ -1,2 +1,2 @@
--Tu avec carté {count} itém has
-+Tu avec carte {count} item has
-EOD
+      expected = (<<-EOD.gsub(/^\s+/,'').encode('UTF-16LE').chomp)
+        @@ -1,2 +1,2 @@
+        -Tu avec carté {count} itém has
+        +Tu avec carte {count} item has
+      EOD
       expect(hunk.diff(:unified).to_s == expected).to eql true
     end
 
     it 'should be able to produce a context diff from the two pieces' do
-      expected =
-(<<-EOD.encode('UTF-16LE').chomp)
-***************
-*** 1,2 ****
-!Tu avec carté {count} itém has
---- 1,2 ----
-!Tu avec carte {count} item has
-EOD
+      expected = (<<-EOD.gsub(/^\s+/,'').encode('UTF-16LE').chomp)
+        ***************
+        *** 1,2 ****
+        !Tu avec carté {count} itém has
+        --- 1,2 ----
+        !Tu avec carte {count} item has
+      EOD
 
       expect(hunk.diff(:context).to_s == expected).to eql true
     end
 
     it 'should be able to produce an old diff from the two pieces' do
-      expected =
-(<<-EOD.encode('UTF-16LE').chomp)
-1,2c1,2
-< Tu avec carté {count} itém has
----
-> Tu avec carte {count} item has
-
-EOD
+      expected = (<<-EOD.gsub(/^ +/,'').encode('UTF-16LE').chomp)
+        1,2c1,2
+        < Tu avec carté {count} itém has
+        ---
+        > Tu avec carte {count} item has
+
+      EOD
       expect(hunk.diff(:old).to_s == expected).to eql true
     end
 
     it 'should be able to produce a reverse ed diff from the two pieces' do
-      expected =
-(<<-EOD.encode('UTF-16LE').chomp)
-c1,2
-Tu avec carte {count} item has
-.
+      expected = (<<-EOD.gsub(/^ +/,'').encode('UTF-16LE').chomp)
+        c1,2
+        Tu avec carte {count} item has
+        .
 
-EOD
+      EOD
       expect(hunk.diff(:reverse_ed).to_s == expected).to eql true
     end
+
+    context 'with empty first data set' do
+      let(:old_data) { [] }
+
+      it 'should be able to produce a unified diff' do
+        expected = (<<-EOD.gsub(/^\s+/,'').encode('UTF-16LE').chomp)
+          @@ -1 +1,2 @@
+          +Tu avec carte {count} item has
+        EOD
+        expect(hunk.diff(:unified).to_s == expected).to eql true
+      end
+    end
+
   end
 end