Support HEAD request and header parsing

lib/gitlab.rb

@@ -8,6 +8,7 @@
 require 'gitlab/headers/total'
 require 'gitlab/paginated_response'
 require 'gitlab/file_response'
+require 'gitlab/header_response'
 require 'gitlab/request'
 require 'gitlab/api'
 require 'gitlab/client'

lib/gitlab/client/repository_files.rb

@@ -56,6 +56,26 @@ def get_file(project, file_path, ref)
           })
     end
 
+    # Gets a repository file metadata.
+    #
+    # @example
+    #   Gitlab.get_file_metadata(42, "README.md", "master")
+    #
+    # @param  [Integer, String] project The ID or name of a project.
+    # @param  [String] file_path The full path of the file.
+    # @param  [String] ref The name of branch, tag or commit.
+    # @return [Gitlab::ObjectifiedHash]
+    def get_file_metadata(project, file_path, ref)
+      head(
+        "/projects/#{url_encode project}/repository/files/#{url_encode file_path}",
+        query: { ref: ref },
+        format: nil,
+        parser: proc do |_body, _format|
+          ::Gitlab::HeaderResponse.new
+        end
+      )
+    end
+
     # Creates a new repository file.
     #
     # @example

lib/gitlab/header_response.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+module Gitlab
+  class HeaderResponse
+    GITLAB_HEADER = 'x-gitlab-'
+
+    def initialize
+      @headers = {}
+    end
+
+    def empty?
+      headers.empty?
+    end
+
+    def to_hash
+      headers
+    end
+    alias to_h to_hash
+
+    def method_missing(method, *args, &)
+      if headers.key?(method)
+        headers[method]
+      else
+        super
+      end
+    end
+
+    def respond_to_missing?(method, include_private = false)
+      headers.key?(method) || super
+    end
+
+    def inspect
+      "#<#{self.class}:#{object_id} #{headers}>"
+    end
+
+    def parse_headers!(headers)
+      @headers = headers.select { |header, _value| header.include?(GITLAB_HEADER) }
+                        .map { |header, value| { header_key(header) => value[0] } }
+                        .reduce(&:merge)
+    end
+
+    private
+
+    attr_reader :headers
+
+    def header_key(header)
+      header.gsub(GITLAB_HEADER, '').tr('-', '_').to_sym
+    end
+  end
+end

lib/gitlab/request.rb

@@ -8,6 +8,8 @@ module Gitlab
   class Request
     include HTTParty
 
+    SUPPORTED_METHODS = %i[head get post put patch delete].freeze
+
     format :json
     maintain_method_across_redirects true
     headers 'Accept' => 'application/json', 'Content-Type' => 'application/x-www-form-urlencoded'
@@ -39,7 +41,7 @@ def self.decode(response)
       raise Error::Parsing, 'The response is not a valid JSON'
     end
 
-    %w[get post put patch delete].each do |method|
+    SUPPORTED_METHODS.each do |method|
       define_method method do |path, options = {}|
         params = options.dup
 

spec/gitlab/client/repository_files_spec.rb

@@ -50,6 +50,17 @@
     end
   end
 
+  describe '.get_file_metadata' do
+    before do
+      stub_head('/projects/3/repository/files/README%2Emd?ref=master', 'empty')
+      @file = Gitlab.get_file_metadata(3, 'README.md', 'master')
+    end
+
+    it 'gets the correct resource' do
+      expect(a_head('/projects/3/repository/files/README%2Emd?ref=master')).to have_been_made
+    end
+  end
+
   describe '.create_file' do
     let(:api_path) { '/projects/3/repository/files/path' }
 

spec/gitlab/header_response_spec.rb

@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::HeaderResponse do
+  subject(:resp) { described_class.new }
+
+  let(:headers) do
+    {
+      'x-gitlab-blob-size' => ['42'],
+      'x-gitlab-commit-id' => ['foobar'],
+      'content-type' => ['application/json']
+    }
+  end
+
+  describe '.empty?' do
+    it 'returns false' do
+      expect(resp).to be_empty
+    end
+  end
+
+  describe '.to_hash' do
+    it 'empty hash after init' do
+      expect(resp.to_hash).to eq({})
+    end
+  end
+
+  describe '.parse_headers!' do
+    subject(:resp_with_h) do
+      resp.parse_headers!(headers)
+      resp
+    end
+
+    it 'parses headers' do
+      expect(resp_with_h.to_h).to eq(
+        {
+          blob_size: '42',
+          commit_id: 'foobar'
+        }
+      )
+    end
+
+    it 'handles getters' do
+      expect(resp_with_h.commit_id).to eq('foobar')
+    end
+
+    it 'nonexistant header' do
+      expect { resp_with_h.expires_in }.to raise_error(NoMethodError)
+    end
+  end
+end

spec/spec_helper.rb

@@ -36,7 +36,7 @@ def load_fixture(name)
   Kernel.srand config.seed
 end
 
-%i[get post put delete patch].each do |method|
+Gitlab::Request::SUPPORTED_METHODS.each do |method|
   define_method "stub_#{method}" do |path, fixture, status_code = 200|
     stub_request(method, "#{Gitlab.endpoint}#{path}")
       .with(headers: { 'PRIVATE-TOKEN' => Gitlab.private_token })