In version 1.4 diff-lcs has minorly changed its format

This commit deals with both versions, as its just header notation thats
changed. I'm not sure either is more correct than the other but its
harmless to our diffing process.

Some additional `\n` changes are due to the string type change, `"\\n"`
is the same as `'\n'`.

Author: JonRowe

spec/rspec/support/differ_spec.rb

@@ -7,14 +7,26 @@
 module RSpec
   module Support
     describe Differ do
+
+      # In the updated version of diff-lcs several diff headers change format slightly
+      # compensate for this and change minimum version in RSpec 4
+      if Diff::LCS::VERSION.to_f < 1.4
+        one_line_header = "-1,2 +1,2"
+        removing_two_line_header = "-1,3 +1"
+      else
+        one_line_header = "-1 +1"
+        removing_two_line_header = "-1,3 +1,5"
+      end
+
       describe '#diff' do
         let(:differ) { RSpec::Support::Differ.new }
 
         it "outputs unified diff of two strings" do
           expected = "foo\nzap\nbar\nthis\nis\nsoo\nvery\nvery\nequal\ninsert\na\nanother\nline\n"
           actual   = "foo\nbar\nzap\nthis\nis\nsoo\nvery\nvery\nequal\ninsert\na\nline\n"
 
-          expected_diff = <<-'EOD'
+          if Diff::LCS::VERSION.to_f < 1.4
+            expected_diff = <<-'EOD'
 
 
 @@ -1,6 +1,6 @@
@@ -32,6 +44,25 @@ module Support
 -another
  line
 EOD
+          else
+            expected_diff = <<-'EOD'
+
+
+@@ -1,4 +1,6 @@
+ foo
+-zap
+ bar
++zap
+ this
+@@ -9,6 +11,7 @@
+ equal
+ insert
+ a
+-another
+ line
+EOD
+          end
+
 
           diff = differ.diff(actual, expected)
           expect(diff).to be_diffed_as(expected_diff)
@@ -41,25 +72,45 @@ module Support
           expected = "foo\nzap\nbar\nthis\nis\nsoo\nvery\nvery\nequal\ninsert\na\nanother\nline\n"
           actual   = "foo\nbar\nzap\nthis\nis\nsoo\nvery\nvery\nequal\ninsert\na\nline\n"
 
-          expected_diff = dedent(<<-'EOS')
-            |
-            |
-            |@@ -1,6 +1,6 @@
-            | foo
-            |-zap
-            | bar
-            |+zap
-            | this
-            | is
-            | soo
-            |@@ -9,6 +9,5 @@
-            | equal
-            | insert
-            | a
-            |-another
-            | line
-            |
-          EOS
+          if Diff::LCS::VERSION.to_f < 1.4
+            expected_diff = dedent(<<-'EOS')
+              |
+              |
+              |@@ -1,6 +1,6 @@
+              | foo
+              |-zap
+              | bar
+              |+zap
+              | this
+              | is
+              | soo
+              |@@ -9,6 +9,5 @@
+              | equal
+              | insert
+              | a
+              |-another
+              | line
+              |
+            EOS
+          else
+            expected_diff = dedent(<<-'EOS')
+              |
+              |
+              |@@ -1,4 +1,6 @@
+              | foo
+              |-zap
+              | bar
+              |+zap
+              | this
+              |@@ -9,6 +11,7 @@
+              | equal
+              | insert
+              | a
+              |-another
+              | line
+              |
+            EOS
+          end
 
           diff = differ.diff(actual, expected)
           expect(diff).to be_diffed_as(expected_diff)
@@ -94,7 +145,7 @@ def differ_ivars
             actual   = "Tu avec carté {count} itém has\n".encode('UTF-16LE')
             expected_diff = <<-EOD.encode('UTF-16LE')
 
-@@ -1,2 +1,2 @@
+@@ #{one_line_header} @@
 -Tu avec carte {count} item has
 +Tu avec carté {count} itém has
 EOD
@@ -106,15 +157,15 @@ def differ_ivars
           it 'handles differently encoded strings that are compatible' do
             expected = "abc\n".encode('us-ascii')
             actual   = "강인철\n".encode('UTF-8')
-            expected_diff = "\n@@ -1,2 +1,2 @@\n-abc\n+강인철\n"
+            expected_diff = "\n@@ #{one_line_header} @@\n-abc\n+강인철\n"
             diff = differ.diff(actual, expected)
             expect(diff).to be_diffed_as(expected_diff)
           end
 
           it 'uses the default external encoding when the two strings have incompatible encodings', :failing_on_appveyor do
             expected = "Tu avec carte {count} item has\n"
             actual   = "Tu avec carté {count} itém has\n".encode('UTF-16LE')
-            expected_diff = "\n@@ -1,2 +1,2 @@\n-Tu avec carte {count} item has\n+Tu avec carté {count} itém has\n"
+            expected_diff = "\n@@ #{one_line_header} @@\n-Tu avec carte {count} item has\n+Tu avec carté {count} itém has\n"
 
             diff = differ.diff(actual, expected)
             expect(diff).to be_diffed_as(expected_diff)
@@ -202,7 +253,7 @@ def inspect; "<BrokenObject>"; end
 
           expected_diff = <<-EOD
 
-@@ -1,2 +1,2 @@
+@@ #{one_line_header} @@
 -[]
 +[<BrokenObject>]
 EOD
@@ -213,7 +264,7 @@ def inspect; "<BrokenObject>"; end
           diff = differ.diff(["a\r\nb"], ["a\r\nc"])
           expected_diff = <<-EOD
 
-@@ -1,2 +1,2 @@
+@@ #{one_line_header} @@
 -a\\r\\nc
 +a\\r\\nb
 EOD
@@ -262,7 +313,7 @@ def inspect; "<BrokenObject>"; end
 
         it 'outputs unified diff message of two hashes with differing encoding', :failing_on_appveyor do
           expected_diff = %Q{
-@@ -1,2 +1,2 @@
+@@ #{one_line_header} @@
 -"a" => "a",
 #{ (RUBY_VERSION.to_f > 1.8) ?  %Q{+"ö" => "ö"} : '+"\303\266" => "\303\266"' },
 }
@@ -273,7 +324,7 @@ def inspect; "<BrokenObject>"; end
 
         it 'outputs unified diff message of two hashes with encoding different to key encoding', :failing_on_appveyor do
           expected_diff = %Q{
-@@ -1,2 +1,2 @@
+@@ #{one_line_header} @@
 -:a => "a",
 #{ (RUBY_VERSION.to_f > 1.8) ?  %Q{+\"한글\" => \"한글2\"} : '+"\355\225\234\352\270\200" => "\355\225\234\352\270\2002"' },
 }
@@ -284,7 +335,7 @@ def inspect; "<BrokenObject>"; end
 
         it "outputs unified diff message of two hashes with object keys" do
           expected_diff = %Q{
-@@ -1,2 +1,2 @@
+@@ #{one_line_header} @@
 -["a", "c"] => "b",
 +["d", "c"] => "b",
 }
@@ -299,7 +350,7 @@ def inspect; "<BrokenObject>"; end
 
         it "outputs unified diff message of two hashes with Time object keys" do
           expected_diff = %Q{
-@@ -1,2 +1,2 @@
+@@ #{one_line_header} @@
 -#{formatted_time} => "b",
 +#{formatted_time} => "c",
 }
@@ -310,7 +361,7 @@ def inspect; "<BrokenObject>"; end
 
         it "outputs unified diff message of two hashes with hashes inside them" do
           expected_diff = %Q{
-@@ -1,2 +1,2 @@
+@@ #{one_line_header} @@
 -"b" => {"key_1"=>#{formatted_time}},
 +"c" => {"key_1"=>#{formatted_time}},
 }
@@ -328,7 +379,7 @@ def inspect; "<BrokenObject>"; end
 
         it "outputs unified diff message of two arrays with Time object keys" do
           expected_diff = %Q{
-@@ -1,2 +1,2 @@
+@@ #{one_line_header} @@
 -[#{formatted_time}, "b"]
 +[#{formatted_time}, "c"]
 }
@@ -339,7 +390,7 @@ def inspect; "<BrokenObject>"; end
 
         it "outputs unified diff message of two arrays with hashes inside them" do
           expected_diff = %Q{
-@@ -1,2 +1,2 @@
+@@ #{one_line_header} @@
 -[{"b"=>#{formatted_time}}, "c"]
 +[{"a"=>#{formatted_time}}, "c"]
 }
@@ -368,23 +419,23 @@ def inspect; "<BrokenObject>"; end
         end
 
         it "splits items with newlines" do
-          expected_diff = <<'EOD'
+          expected_diff = <<"EOD"
 
-@@ -1,3 +1 @@
--a\nb
--c\nd
+@@ #{removing_two_line_header} @@
+-a\\nb
+-c\\nd
 EOD
 
           diff = differ.diff [], ["a\nb", "c\nd"]
           expect(diff).to be_diffed_as(expected_diff)
         end
 
         it "shows inner arrays on a single line" do
-          expected_diff = <<'EOD'
+          expected_diff = <<"EOD"
 
-@@ -1,3 +1 @@
--a\nb
--["c\nd"]
+@@ #{removing_two_line_header} @@
+-a\\nb
+-["c\\nd"]
 EOD
 
           diff = differ.diff [], ["a\nb", ["c\nd"]]
@@ -434,7 +485,7 @@ def inspect; "<BrokenObject>"; end
 
             expected_diff = dedent(<<-EOS)
               |
-              |@@ -1,2 +1,2 @@
+              |@@ #{one_line_header} @@
               |-[#<SimpleDelegator(#{object.inspect})>]
               |+[#{object.inspect}]
               |
@@ -456,7 +507,7 @@ def inspect; "<BrokenObject>"; end
 
             expected_diff = dedent(<<-EOS)
               |
-              |@@ -1,2 +1,2 @@
+              |@@ #{one_line_header} @@
               |-"oop"
               |+"oof"
               |
@@ -473,7 +524,7 @@ def inspect; "<BrokenObject>"; end
           it "outputs colored diffs" do
             expected = "foo bar baz\n"
             actual = "foo bang baz\n"
-            expected_diff = "\e[0m\n\e[0m\e[34m@@ -1,2 +1,2 @@\n\e[0m\e[31m-foo bang baz\n\e[0m\e[32m+foo bar baz\n\e[0m"
+            expected_diff = "\e[0m\n\e[0m\e[34m@@ #{one_line_header} @@\n\e[0m\e[31m-foo bang baz\n\e[0m\e[32m+foo bar baz\n\e[0m"
 
             diff = differ.diff(expected,actual)
             expect(diff).to be_diffed_as(expected_diff)