Add spec for Gitlab::Git::Repository#attributes

seed_helper changed because testing requires attributes file in repo,
but repo was not a real git repo but instead faked.

spec/lib/gitlab/git/attributes_parser_spec.rb

@@ -94,7 +94,7 @@ describe Gitlab::Git::AttributesParser, :seed_helper do
     # It's a bit hard to test for something _not_ being processed. As such we'll
     # just test the number of entries.
     it 'ignores any comments and empty lines' do
-      expect(subject.patterns.length).to eq(10)
+      expect(subject.patterns.length).to eq(12)
     end
   end
 
@@ -126,7 +126,7 @@ describe Gitlab::Git::AttributesParser, :seed_helper do
 
   describe '#each_line' do
     it 'iterates over every line in the attributes file' do
-      args = [String] * 14 # the number of lines in the file
+      args = [String] * 16 # the number of lines in the file
 
       expect { |b| subject.each_line(&b) }.to yield_successive_args(*args)
     end

spec/lib/gitlab/git/repository_spec.rb

@@ -1194,6 +1194,34 @@ describe Gitlab::Git::Repository, :seed_helper do
     end
   end
 
+  describe '#gitattribute' do
+    let(:repository) { Gitlab::Git::Repository.new('default', TEST_GITATTRIBUTES_REPO_PATH, '') }
+
+    after do
+      ensure_seeds
+    end
+
+    it 'returns matching language attribute' do
+      expect(repository.gitattribute("custom-highlighting/test.gitlab-custom", 'gitlab-language')).to eq('ruby')
+    end
+
+    it 'returns matching language attribute with additional options' do
+      expect(repository.gitattribute("custom-highlighting/test.gitlab-cgi", 'gitlab-language')).to eq('erb?parent=json')
+    end
+
+    it 'returns nil if nothing matches' do
+      expect(repository.gitattribute("report.xslt", 'gitlab-language')).to eq(nil)
+    end
+
+    context 'without gitattributes file' do
+      let(:repository) { Gitlab::Git::Repository.new('default', TEST_REPO_PATH, '') }
+
+      it 'returns nil' do
+        expect(repository.gitattribute("README.md", 'gitlab-language')).to eq(nil)
+      end
+    end
+  end
+
   describe '#ref_exists?' do
     it 'returns true for an existing tag' do
       expect(repository.ref_exists?('refs/heads/master')).to eq(true)

spec/support/helpers/seed_helper.rb

+# frozen_string_literal: true
+
 require_relative 'test_env'
 
 # This file is specific to specs in spec/lib/gitlab/git/
 
 SEED_STORAGE_PATH      = TestEnv.repos_path
-TEST_REPO_PATH         = 'gitlab-git-test.git'.freeze
-TEST_NORMAL_REPO_PATH  = 'not-bare-repo.git'.freeze
-TEST_MUTABLE_REPO_PATH = 'mutable-repo.git'.freeze
-TEST_BROKEN_REPO_PATH  = 'broken-repo.git'.freeze
+TEST_REPO_PATH         = 'gitlab-git-test.git'
+TEST_NORMAL_REPO_PATH  = 'not-bare-repo.git'
+TEST_MUTABLE_REPO_PATH = 'mutable-repo.git'
+TEST_BROKEN_REPO_PATH  = 'broken-repo.git'
+TEST_GITATTRIBUTES_REPO_PATH = 'with-git-attributes.git'
 
 module SeedHelper
-  GITLAB_GIT_TEST_REPO_URL = File.expand_path('../gitlab-git-test.git', __dir__).freeze
+  GITLAB_GIT_TEST_REPO_URL = File.expand_path('../gitlab-git-test.git', __dir__)
 
   def ensure_seeds
     if File.exist?(SEED_STORAGE_PATH)
@@ -66,6 +69,11 @@ module SeedHelper
   end
 
   def create_git_attributes
+    system(git_env, *%W(#{Gitlab.config.git.bin_path} clone --bare #{TEST_REPO_PATH} #{TEST_GITATTRIBUTES_REPO_PATH}),
+           chdir: SEED_STORAGE_PATH,
+           out: '/dev/null',
+           err: '/dev/null')
+
     dir = File.join(SEED_STORAGE_PATH, 'with-git-attributes.git', 'info')
 
     FileUtils.mkdir_p(dir)
@@ -82,6 +90,8 @@ foo/bar.* foo
 *.cgi     key=value?p1=v1&p2=v2
 /*.png    gitlab-language=png
 *.binary  binary
+/custom-highlighting/*.gitlab-custom gitlab-language=ruby
+/custom-highlighting/*.gitlab-cgi gitlab-language=erb?parent=json
 
 # This uses a tab instead of spaces to ensure the parser also supports this.
 *.md\tgitlab-language=markdown