Fix differ support

.travis.yml

@@ -38,6 +38,8 @@ matrix:
   include:
     - rvm: jruby-1.7
       env: JRUBY_OPTS='--dev --1.8'
+    - rvm: 2.7.1
+      env: DIFF_LCS_VERSION="~> 1.3.0"
   allow_failures:
     - rvm: jruby-head
     - rvm: ruby-head

Gemfile

@@ -20,6 +20,12 @@ else
   gem 'rake', '> 12.3.2'
 end
 
+if ENV['DIFF_LCS_VERSION']
+  gem 'diff-lcs', ENV['DIFF_LCS_VERSION']
+else
+  gem 'diff-lcs', '~> 1.4', '>= 1.4.3'
+end
+
 gem 'coderay' # for syntax highlighting
 gem 'yard', '~> 0.9.24', :require => false
 

features/custom_matchers/define_diffable_matcher.feature

@@ -2,7 +2,33 @@ Feature: define diffable matcher
 
   When a matcher is defined as diffable, the output will include a diff of the submitted objects when the objects are more than simple primitives.
 
-  Scenario: define a diffable matcher
+  @skip-when-diff-lcs-1.3
+  Scenario: define a diffable matcher (with diff-lcs 1.4)
+    Given a file named "diffable_matcher_spec.rb" with:
+      """ruby
+      RSpec::Matchers.define :be_just_like do |expected|
+        match do |actual|
+          actual == expected
+        end
+
+        diffable
+      end
+
+      RSpec.describe "two\nlines" do
+        it { is_expected.to be_just_like("three\nlines") }
+      end
+      """
+    When I run `rspec ./diffable_matcher_spec.rb`
+    Then it should fail with:
+      """
+             Diff:
+             @@ -1 +1 @@
+             -three
+             +two
+      """
+
+  @skip-when-diff-lcs-1.4
+  Scenario: define a diffable matcher (with diff-lcs 1.3)
     Given a file named "diffable_matcher_spec.rb" with:
       """ruby
       RSpec::Matchers.define :be_just_like do |expected|
@@ -27,10 +53,53 @@ Feature: define diffable matcher
               lines
       """
 
+  @skip-when-diff-lcs-1.3
   Scenario: Redefine actual
 
     Sometimes is neccessary to overwrite actual to make diffing work, e.g. if `actual` is a name of a file you want to read from. For this to work you need to overwrite `@actual` in your matcher.
 
+    Given a file named "redefine_actual_matcher_spec.rb" with:
+      """ruby
+      RSpec::Matchers.define :have_content do |expected|
+        match do |actual|
+          @actual = File.read(actual).chomp
+
+          values_match? expected, @actual
+        end
+
+        diffable
+      end
+
+      RSpec.describe 'Compare files' do
+        context 'when content is equal' do
+          it { expect('data.txt').to have_content 'Data' }
+        end
+
+        context 'when files are different' do
+          it { expect('data.txt').to have_content "No\nData\nhere" }
+        end
+      end
+      """
+    And a file named "data.txt" with:
+    """
+    Data
+    """
+    When I run `rspec ./redefine_actual_matcher_spec.rb --format documentation`
+    Then the exit status should not be 0
+    And the output should contain:
+    """
+    2 examples, 1 failure
+    """
+    And the output should contain:
+    """
+           @@ -1,4 +1,6 @@
+           -No
+            Data
+           -here
+    """
+
+  @skip-when-diff-lcs-1.4
+  Scenario: Redefine actual (with diff-lcs 1.3)
     Given a file named "redefine_actual_matcher_spec.rb" with:
       """ruby
       RSpec::Matchers.define :have_content do |expected|

features/diffing.feature

@@ -32,7 +32,35 @@ Feature: diffing
                   string
       """
 
-  Scenario: diff for a multiline string and a regexp
+  @skip-when-diff-lcs-1.3
+  Scenario: diff for a multiline string and a regexp on diff-lcs 1.4
+    Given a file named "example_spec.rb" with:
+      """ruby
+      RSpec.describe "a multiline string" do
+        it "is like another string" do
+          expected = /expected/m
+          actual = <<-ACTUAL
+      this is the
+        actual
+          string
+      ACTUAL
+          expect(actual).to match expected
+        end
+      end
+      """
+    When I run `rspec example_spec.rb`
+    Then the output should contain:
+      """
+             Diff:
+             @@ -1,3 +1,5 @@
+             -/expected/m
+             +this is the
+             +  actual
+             +    string
+      """
+
+  @skip-when-diff-lcs-1.4
+  Scenario: diff for a multiline string and a regexp on diff-lcs 1.3
     Given a file named "example_spec.rb" with:
       """ruby
       RSpec.describe "a multiline string" do

features/support/diff_lcs_versions.rb

@@ -0,0 +1,15 @@
+Around "@skip-when-diff-lcs-1.4" do |scenario, block|
+  if Diff::LCS::VERSION.to_f >= 1.4
+    warn "Skipping scenario #{scenario.title} on #{Diff::LCS::VERSION.to_f}"
+  else
+    block.call
+  end
+end
+
+Around "@skip-when-diff-lcs-1.3" do |scenario, block|
+  if Diff::LCS::VERSION.to_f < 1.4
+    warn "Skipping scenario #{scenario.title} on #{Diff::LCS::VERSION.to_f}"
+  else
+    block.call
+  end
+end

spec/rspec/expectations/fail_with_spec.rb

@@ -32,6 +32,8 @@
 end
 
 RSpec.describe RSpec::Expectations, "#fail_with with matchers" do
+  include RSpec::Support::Spec::DiffHelpers
+
   before do
     allow(RSpec::Matchers.configuration).to receive_messages(:color? => false)
   end
@@ -42,7 +44,7 @@
 
     expected_diff = dedent(<<-EOS)
       |
-      |@@ -1,2 +1,2 @@
+      |@@ #{one_line_header} @@
       |-["poo", "car"]
       |+[(a string matching /foo/), (a string matching /bar/)]
       |
@@ -55,14 +57,16 @@
 end
 
 RSpec.describe RSpec::Expectations, "#fail_with with --color" do
+  include RSpec::Support::Spec::DiffHelpers
+
   before do
     allow(RSpec::Matchers.configuration).to receive_messages(:color? => true)
   end
 
   it "tells the differ to use color" 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"
 
     expect {
       RSpec::Expectations.fail_with "message", actual, expected

spec/rspec/matchers/built_in/have_attributes_spec.rb

@@ -1,4 +1,5 @@
 RSpec.describe "#have_attributes matcher" do
+  include RSpec::Support::Spec::DiffHelpers
 
   Person = Struct.new(:name, :age)
 
@@ -36,7 +37,6 @@ def respond_to?(method_name)
   end
 
   describe "expect(...).to have_attributes(with_one_attribute)" do
-
     it_behaves_like "an RSpec matcher", :valid_value => Person.new("Correct name", 33), :invalid_value => Person.new("Wrong Name", 11) do
       let(:matcher) { have_attributes(:name => "Correct name") }
     end
@@ -71,7 +71,7 @@ def count
       allow(RSpec::Matchers.configuration).to receive_messages(:color? => false)
 
       expected_diff = dedent(<<-EOS)
-        |@@ -1,2 +1,2 @@
+        |@@ #{one_line_header} @@
         |-:name => "Wrong Name",
         |+:name => "Correct name",
       EOS
@@ -100,7 +100,6 @@ def count
     end
 
     describe "expect(...).to have_attributes(key => matcher)" do
-
       it "passes when the matchers match" do
         expect(person).to have_attributes(:age => (a_value > 30))
       end
@@ -119,7 +118,6 @@ def count
   end
 
   describe "expect(...).to_not have_attributes(with_one_attribute)" do
-
     it "passes if target does not have any of the expected attributes" do
       expect(person).to_not have_attributes(:age => wrong_age)
     end
@@ -150,7 +148,6 @@ def count
   end
 
   describe "expect(...).to have_attributes(with_multiple_attributes)" do
-
     it_behaves_like "an RSpec matcher", :valid_value => Person.new("Correct name", 33), :invalid_value => Person.new("Wrong Name", 11) do
       let(:matcher) { have_attributes(:name => "Correct name", :age => 33) }
     end
@@ -169,11 +166,11 @@ def count
       allow(RSpec::Matchers.configuration).to receive_messages(:color? => false)
 
       expected_diff = dedent(<<-EOS)
-        |@@ -1,3 +1,3 @@
+        |@@ #{one_line_header(3)} @@
         |-:age => 11,
         |+:age => 33,
-        | :name => "Correct name",
       EOS
+      expected_diff << "\n :name => \"Correct name\",\n" if Diff::LCS::VERSION.to_f < 1.4
 
       expect {
         expect(person).to have_attributes(:name => correct_name, :age => wrong_age)
@@ -194,7 +191,6 @@ def count
   end
 
   describe "expect(...).to_not have_attributes(with_multiple_attributes)" do
-
     it "passes if target has none of the expected attributes" do
       expect(person).to_not have_attributes(:name => wrong_name, :age => wrong_age)
     end
@@ -229,5 +225,4 @@ def count
   def object_inspect(object)
     surface_descriptions_in object.inspect
   end
-
 end

spec/rspec/matchers/built_in/include_spec.rb

@@ -34,6 +34,8 @@ def to_hash
 end
 
 RSpec.describe "#include matcher" do
+  include RSpec::Support::Spec::DiffHelpers
+
   it "is diffable" do
     expect(include("a")).to be_diffable
   end
@@ -87,13 +89,14 @@ def hash.send; :sent; end
                            |+"foo" => 1,
                          END
                        else
-                         dedent(<<-END)
+                         diff = dedent(<<-END)
                            |Diff:
-                           |@@ -1,3 +1,3 @@
+                           |@@ #{one_line_header(3)} @@
                            |-:bar => 3,
                            |+:bar => 2,
-                           | :foo => 1,
                          END
+                         diff << "\n :foo => 1,\n" if Diff::LCS::VERSION.to_f < 1.4
+                         diff
                        end
 
       expect {
@@ -297,7 +300,7 @@ class PseudoHash < SimpleDelegator
           )
         }.to fail_including(dedent(<<-END))
           |Diff:
-          |@@ -1,2 +1,2 @@
+          |@@ #{one_line_header} @@
           |-[{:number=>1}, {:number=>0}, {:number=>3}]
           |+[{:number=>1}, {:number=>2}, {:number=>3}]
         END

spec/rspec/matchers/built_in/match_spec.rb

@@ -1,4 +1,6 @@
 RSpec.describe "expect(...).to match(expected)" do
+  include RSpec::Support::Spec::DiffHelpers
+
   it_behaves_like "an RSpec matcher", :valid_value => 'ab', :invalid_value => 'bc' do
     let(:matcher) { match(/a/) }
   end
@@ -68,7 +70,7 @@
 
     failure_message_that_includes_diff = %r|
 \s*Diff:
-\s*@@ -1,2 \+1,2 @@
+\s*@@ #{Regexp.escape one_line_header} @@
 \s*-/bar/
 \s*\+"foo"|
 

spec/rspec/matchers/dsl_spec.rb

@@ -513,7 +513,13 @@ def foo
         diff = e.message.sub(/\A.*Diff:/m, "Diff:").gsub(/^\s*/, '')
       end
 
-      expect(diff).to eq "Diff:\n@@ -1,3 +1,3 @@\n-line1\n+LINE1\nline2\n"
+      if Diff::LCS::VERSION.to_f < 1.4
+        expected_diff = "Diff:\n@@ -1,3 +1,3 @@\n-line1\n+LINE1\nline2\n"
+      else
+        expected_diff = "Diff:\n@@ -1 +1 @@\n-line1\n+LINE1\n"
+      end
+
+      expect(diff).to eq expected_diff
     end
 
     it 'does not confuse the diffability of different matchers' do