Fix ldiff binary files comparison and output

Before this change, the comparison was reversed and diff were not
detected.

This commit also change the output when a diff is detected to look
like the GNU diff output.

Also fix the support of all other format than :report, by quickly
halting the diff process if there is a binary diff.

lib/diff/lcs/ldiff.rb

@@ -116,24 +116,29 @@ def self.diff?(info_old, info_new, format, output, binary: nil, lines: 0)
     file_length_difference = 0
 
     # Test binary status
-    if @binary.nil?
+    if binary.nil?
       old_bin = info_old.data[0, 4096].include?("\0")
       new_bin = info_new.data[0, 4096].include?("\0")
-      @binary = old_bin || new_bin
+      binary = old_bin || new_bin
     end
 
     # diff yields lots of pieces, each of which is basically a Block object
     if binary
-      diffs = (info_old.data == info_new.data)
+      has_diffs = (info_old.data != info_new.data)
+      if format != :report
+        if has_diffs
+          output << "Binary files #{info_old.filename} and #{info_new.filename} differ\n"
+          return true
+        end
+        return false
+      end
     else
       data_old = info_old.data.lines.to_a
       data_new = info_new.data.lines.to_a
       diffs = Diff::LCS.diff(data_old, data_new)
-      diffs = nil if diffs.empty?
+      return false if diffs.empty?
     end
 
-    return false unless diffs
-
     case format
     when :report
       output << "Files #{info_old.filename} and #{info_new.filename} differ\n"

spec/fixtures/ldiff/output.diff.bin2

@@ -0,0 +1 @@
+Binary files spec/fixtures/file1.bin and spec/fixtures/file2.bin differ

spec/fixtures/ldiff/output.diff.bin2-c

@@ -0,0 +1 @@
+Binary files spec/fixtures/file1.bin and spec/fixtures/file2.bin differ

spec/fixtures/ldiff/output.diff.bin2-e

@@ -0,0 +1 @@
+Binary files spec/fixtures/file1.bin and spec/fixtures/file2.bin differ

spec/fixtures/ldiff/output.diff.bin2-f

@@ -0,0 +1 @@
+Binary files spec/fixtures/file1.bin and spec/fixtures/file2.bin differ

spec/fixtures/ldiff/output.diff.bin2-u

@@ -0,0 +1 @@
+Binary files spec/fixtures/file1.bin and spec/fixtures/file2.bin differ

spec/ldiff_spec.rb

@@ -8,6 +8,8 @@
   # standard:disable Style/HashSyntax
   fixtures = [
     {:name => "output.diff", :left => "aX", :right => "bXaX", :diff => 1},
+    {:name => "output.diff.bin1", :left => "file1.bin", :right => "file1.bin", :diff => 0},
+    {:name => "output.diff.bin2", :left => "file1.bin", :right => "file2.bin", :diff => 1},
     {:name => "output.diff.chef", :left => "old-chef", :right => "new-chef", :diff => 1},
     {:name => "output.diff.chef2", :left => "old-chef2", :right => "new-chef2", :diff => 1}
   ].product([nil, "-e", "-f", "-c", "-u"]).map { |(fixture, flag)|