From 6c00c33403889f9209e62f451c7a614c8da82de5 Mon Sep 17 00:00:00 2001
From: Douglas Barbosa Alexandre <dbalexandre@gmail.com>
Date: Thu, 7 Jul 2016 23:28:10 -0300
Subject: [PATCH 1/6] Add GitLab::Import::Github::Client

---
 lib/gitlab/import/github/client.rb            | 67 +++++++++++++++++++
 lib/gitlab/import/github/options.rb           | 33 +++++++++
 spec/lib/gitlab/import/github/options_spec.rb | 57 ++++++++++++++++
 3 files changed, 157 insertions(+)
 create mode 100644 lib/gitlab/import/github/client.rb
 create mode 100644 lib/gitlab/import/github/options.rb
 create mode 100644 spec/lib/gitlab/import/github/options_spec.rb

diff --git a/lib/gitlab/import/github/client.rb b/lib/gitlab/import/github/client.rb
new file mode 100644
index 000000000000..e286a9a22bf4
--- /dev/null
+++ b/lib/gitlab/import/github/client.rb
@@ -0,0 +1,67 @@
+module Gitlab
+  module Import
+    module Github
+      class Client
+        def initialize(project)
+          @repo = project.import_source
+          @repo_url = project.import_url
+          @credentials = project.import_data.credentials
+          @options = Options.new
+        end
+
+        private
+
+        attr_reader :credentials, :options, :repo, :repo_url
+
+        SAFE_REMAINING_REQUESTS = 100
+        SAFE_SLEEP_TIME = 500
+
+        def client
+          @client ||= begin
+            Octokit.auto_paginate = false
+
+            Octokit::Client.new(
+              access_token: access_token,
+              api_endpoint: options.endpoint,
+              connection_options: {
+                ssl: { verify: options.verify_ssl }
+              }
+           )
+          end
+        end
+
+        def access_token
+          credentials[:user]
+        end
+
+        def rate_limit
+          client.rate_limit!
+        end
+
+        def rate_limit_exceed?
+          rate_limit.remaining <= SAFE_REMAINING_REQUESTS
+        end
+
+        def rate_limit_sleep_time
+          rate_limit.resets_in + SAFE_SLEEP_TIME
+        end
+
+        def request
+          sleep rate_limit_sleep_time if rate_limit_exceed?
+
+          data = yield
+
+          last_response = client.last_response
+
+          while last_response.rels[:next]
+            sleep rate_limit_sleep_time if rate_limit_exceed?
+            last_response = last_response.rels[:next].get
+            data.concat(last_response.data) if last_response.data.is_a?(Array)
+          end
+
+          data
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/import/github/options.rb b/lib/gitlab/import/github/options.rb
new file mode 100644
index 000000000000..dc7d8feb7c7c
--- /dev/null
+++ b/lib/gitlab/import/github/options.rb
@@ -0,0 +1,33 @@
+module Gitlab
+  module Import
+    module Github
+      class Options
+        def endpoint
+          client_options[:site]
+        end
+
+        def verify_ssl
+          options.fetch(:verify_ssl, true)
+        end
+
+        private
+
+        def client_options
+          @client_options ||= options.fetch(:args, options)[:client_options]
+        end
+
+        def custom_options
+          Gitlab.config.omniauth.providers.find { |provider| provider.name == 'github' }
+        end
+
+        def default_options
+          OmniAuth::Strategies::GitHub.default_options
+        end
+
+        def options
+          @options ||= (custom_options || default_options).deep_symbolize_keys
+        end
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/import/github/options_spec.rb b/spec/lib/gitlab/import/github/options_spec.rb
new file mode 100644
index 000000000000..2f40f9c18c94
--- /dev/null
+++ b/spec/lib/gitlab/import/github/options_spec.rb
@@ -0,0 +1,57 @@
+require 'spec_helper'
+
+describe Gitlab::Import::Github::Options, lib: true do
+  subject(:options) { described_class.new }
+
+  context 'with custom options' do
+    let(:github) do
+      Settingslogic.new(
+        'name' => 'github',
+        'app_id' => '123456',
+        'app_secret' => '123456',
+        'verify_ssl' => false,
+        'args' => {
+          'client_options' => {
+            'site' => 'https://github.mycompany.com',
+            'authorize_url' => 'https://github.mycompany.com/login/oauth/authorize',
+            'token_url' => 'https://github.mycompany.com/login/oauth/access_token'
+          }
+        }
+      )
+    end
+
+    before do
+      allow(Gitlab.config.omniauth).to receive(:providers).and_return([github])
+    end
+
+    describe '#endpoint' do
+      it 'returns custom API endpoint' do
+        expect(options.endpoint).to eq 'https://github.mycompany.com'
+      end
+    end
+
+    describe '#verify_ssl' do
+      it 'returns custom value' do
+        expect(options.verify_ssl).to eq false
+      end
+    end
+  end
+
+  context 'with default options' do
+    before do
+      allow(Gitlab.config.omniauth).to receive(:providers).and_return([])
+    end
+
+    describe '#endpoint' do
+      it 'returns GitHub API endpoint' do
+        expect(options.endpoint).to eq 'https://api.github.com'
+      end
+    end
+
+    describe '#verify_ssl' do
+      it 'returns true' do
+        expect(options.verify_ssl).to eq true
+      end
+    end
+  end
+end
-- 
GitLab


From 9af6b08fe7885d13400b6b459e47c3546d14d456 Mon Sep 17 00:00:00 2001
From: Douglas Barbosa Alexandre <dbalexandre@gmail.com>
Date: Fri, 8 Jul 2016 14:16:04 -0300
Subject: [PATCH 2/6] Add a mapper to handle with GitHub labels

---
 lib/gitlab/import/github/client.rb            |  4 +++
 lib/gitlab/import/github/mapper/label.rb      | 30 +++++++++++++++++++
 .../gitlab/import/github/mapper/label_spec.rb | 30 +++++++++++++++++++
 3 files changed, 64 insertions(+)
 create mode 100644 lib/gitlab/import/github/mapper/label.rb
 create mode 100644 spec/lib/gitlab/import/github/mapper/label_spec.rb

diff --git a/lib/gitlab/import/github/client.rb b/lib/gitlab/import/github/client.rb
index e286a9a22bf4..228c6c5e692d 100644
--- a/lib/gitlab/import/github/client.rb
+++ b/lib/gitlab/import/github/client.rb
@@ -9,6 +9,10 @@ def initialize(project)
           @options = Options.new
         end
 
+        def labels
+          request { client.labels(repo, per_page: 100) }
+        end
+
         private
 
         attr_reader :credentials, :options, :repo, :repo_url
diff --git a/lib/gitlab/import/github/mapper/label.rb b/lib/gitlab/import/github/mapper/label.rb
new file mode 100644
index 000000000000..6e2f4cb99a97
--- /dev/null
+++ b/lib/gitlab/import/github/mapper/label.rb
@@ -0,0 +1,30 @@
+module Gitlab
+  module Import
+    module Github
+      module Mapper
+        class Label
+          def initialize(project, client)
+            @project = project
+            @client  = client
+          end
+
+          def each
+            client.labels.each do |raw|
+              label = ::Label.new(
+                project: project,
+                title: raw.name,
+                color: "##{raw.color}"
+              )
+
+              yield(label)
+            end
+          end
+
+          private
+
+          attr_reader :project, :client
+        end
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/import/github/mapper/label_spec.rb b/spec/lib/gitlab/import/github/mapper/label_spec.rb
new file mode 100644
index 000000000000..c02758cda442
--- /dev/null
+++ b/spec/lib/gitlab/import/github/mapper/label_spec.rb
@@ -0,0 +1,30 @@
+require 'spec_helper'
+
+describe Gitlab::Import::Github::Mapper::Label, lib: true do
+  let(:project) { create(:empty_project) }
+  let(:client)  { double(labels: response) }
+
+  let(:response) do
+    [
+      double(
+        url: 'https://api.github.com/repos/octocat/Hello-World/labels/bug',
+        name: 'Bug',
+        color: 'f29513'
+      )
+    ]
+  end
+
+  subject(:mapper) { described_class.new(project, client) }
+
+  describe '#each' do
+    it 'yields successively with Label' do
+      expect { |block| mapper.each(&block) }.to yield_successive_args(Label)
+    end
+
+    it 'matches the Label attributes' do
+      mapper.each do |label|
+        expect(label).to have_attributes(project: project, name: 'Bug', color: '#f29513')
+      end
+    end
+  end
+end
-- 
GitLab


From 15112fbe561d74ca8c687725ac17e040b0653a48 Mon Sep 17 00:00:00 2001
From: Douglas Barbosa Alexandre <dbalexandre@gmail.com>
Date: Fri, 8 Jul 2016 14:16:28 -0300
Subject: [PATCH 3/6] Add an action to import labels from GitHub

---
 lib/gitlab/import/action/import_labels.rb     | 19 ++++++++++++++++
 .../import/action/import_labels_spec.rb       | 22 +++++++++++++++++++
 2 files changed, 41 insertions(+)
 create mode 100644 lib/gitlab/import/action/import_labels.rb
 create mode 100644 spec/lib/gitlab/import/action/import_labels_spec.rb

diff --git a/lib/gitlab/import/action/import_labels.rb b/lib/gitlab/import/action/import_labels.rb
new file mode 100644
index 000000000000..57c6c581fad9
--- /dev/null
+++ b/lib/gitlab/import/action/import_labels.rb
@@ -0,0 +1,19 @@
+module Gitlab
+  module Import
+    module Action
+      class ImportLabels
+        def initialize(project, client)
+          @mapper = Github::Mapper::Label.new(project, client)
+        end
+
+        def execute
+          mapper.each(&:save)
+        end
+
+        private
+
+        attr_reader :mapper
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/import/action/import_labels_spec.rb b/spec/lib/gitlab/import/action/import_labels_spec.rb
new file mode 100644
index 000000000000..be0cb2d93dc5
--- /dev/null
+++ b/spec/lib/gitlab/import/action/import_labels_spec.rb
@@ -0,0 +1,22 @@
+require 'spec_helper'
+
+describe Gitlab::Import::Action::ImportLabels, lib: true do
+  let(:project) { create(:empty_project) }
+  let(:client)  { double(labels: response) }
+
+  let(:response) do
+    [
+      double(
+        url: 'https://api.github.com/repos/octocat/Hello-World/labels/bug',
+        name: 'Bug',
+        color: 'f29513'
+      )
+    ]
+  end
+
+  subject(:action) { described_class.new(project, client) }
+
+  describe '#execute' do
+    it { expect { subject.execute }.to change(Label, :count).by(1) }
+  end
+end
-- 
GitLab


From 80f884f0355bbb97e1b65b0f212b2025a748b865 Mon Sep 17 00:00:00 2001
From: Douglas Barbosa Alexandre <dbalexandre@gmail.com>
Date: Fri, 8 Jul 2016 15:03:53 -0300
Subject: [PATCH 4/6] Keeps track of errors when importing GitHub labels

---
 lib/gitlab/import/action/import_labels.rb     | 15 ++++++++++++---
 lib/gitlab/import/result.rb                   | 19 +++++++++++++++++++
 .../import/action/import_labels_spec.rb       | 17 +++++++++++++++--
 spec/lib/gitlab/import/result_spec.rb         | 17 +++++++++++++++++
 4 files changed, 63 insertions(+), 5 deletions(-)
 create mode 100644 lib/gitlab/import/result.rb
 create mode 100644 spec/lib/gitlab/import/result_spec.rb

diff --git a/lib/gitlab/import/action/import_labels.rb b/lib/gitlab/import/action/import_labels.rb
index 57c6c581fad9..8e9c9788075a 100644
--- a/lib/gitlab/import/action/import_labels.rb
+++ b/lib/gitlab/import/action/import_labels.rb
@@ -2,17 +2,26 @@ module Gitlab
   module Import
     module Action
       class ImportLabels
-        def initialize(project, client)
+        def initialize(project, client, result)
           @mapper = Github::Mapper::Label.new(project, client)
+          @result = result
         end
 
         def execute
-          mapper.each(&:save)
+          mapper.each do |label|
+            next if label.save
+
+            label.errors.full_messages.each do |error|
+              result.errors << "#{label.name}: #{error}"
+            end
+          end
+
+          result
         end
 
         private
 
-        attr_reader :mapper
+        attr_reader :mapper, :result
       end
     end
   end
diff --git a/lib/gitlab/import/result.rb b/lib/gitlab/import/result.rb
new file mode 100644
index 000000000000..971a758cc603
--- /dev/null
+++ b/lib/gitlab/import/result.rb
@@ -0,0 +1,19 @@
+module Gitlab
+  module Import
+    class Result
+      attr_reader :errors
+
+      def initialize
+        @errors = []
+      end
+
+      def success?
+        errors.blank?
+      end
+
+      def failed?
+        !success?
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/import/action/import_labels_spec.rb b/spec/lib/gitlab/import/action/import_labels_spec.rb
index be0cb2d93dc5..4f8691e9af49 100644
--- a/spec/lib/gitlab/import/action/import_labels_spec.rb
+++ b/spec/lib/gitlab/import/action/import_labels_spec.rb
@@ -3,9 +3,15 @@
 describe Gitlab::Import::Action::ImportLabels, lib: true do
   let(:project) { create(:empty_project) }
   let(:client)  { double(labels: response) }
+  let(:result)  { double(errors: []) }
 
   let(:response) do
     [
+      double(
+        url: 'https://api.github.com/repos/octocat/Hello-World/labels/bug',
+        name: 'Bug',
+        color: 'f29513'
+      ),
       double(
         url: 'https://api.github.com/repos/octocat/Hello-World/labels/bug',
         name: 'Bug',
@@ -14,9 +20,16 @@
     ]
   end
 
-  subject(:action) { described_class.new(project, client) }
+  subject(:action) { described_class.new(project, client, result) }
 
   describe '#execute' do
-    it { expect { subject.execute }.to change(Label, :count).by(1) }
+    it 'persists labels' do
+      expect { subject.execute }.to change(Label, :count).by(1)
+    end
+
+    it 'keeps track of errors' do
+      result = subject.execute
+      expect(result.errors).to eq ['Bug: Title has already been taken']
+    end
   end
 end
diff --git a/spec/lib/gitlab/import/result_spec.rb b/spec/lib/gitlab/import/result_spec.rb
new file mode 100644
index 000000000000..3da5f38d3404
--- /dev/null
+++ b/spec/lib/gitlab/import/result_spec.rb
@@ -0,0 +1,17 @@
+require 'spec_helper'
+
+describe Gitlab::Import::Result, lib: true do
+  subject(:result) { described_class.new }
+
+  it 'success when errors is empty' do
+    expect(result).to be_success
+    expect(result).not_to be_failed
+  end
+
+  it 'failed when errors is not empty' do
+    result.errors << 'Something goes wrong'
+
+    expect(result).to be_failed
+    expect(result).not_to be_success
+  end
+end
-- 
GitLab


From cb8e9bb6bb0cb3712b888f79d2e8e324724742ad Mon Sep 17 00:00:00 2001
From: Douglas Barbosa Alexandre <dbalexandre@gmail.com>
Date: Fri, 8 Jul 2016 17:04:26 -0300
Subject: [PATCH 5/6] Add a mapper to handle with GitHub milestones

---
 lib/gitlab/import/github/client.rb            |  7 +-
 lib/gitlab/import/github/mapper/label.rb      |  2 +
 lib/gitlab/import/github/mapper/milestone.rb  | 37 ++++++++++
 .../import/github/mapper/milestone_spec.rb    | 72 +++++++++++++++++++
 4 files changed, 117 insertions(+), 1 deletion(-)
 create mode 100644 lib/gitlab/import/github/mapper/milestone.rb
 create mode 100644 spec/lib/gitlab/import/github/mapper/milestone_spec.rb

diff --git a/lib/gitlab/import/github/client.rb b/lib/gitlab/import/github/client.rb
index 228c6c5e692d..3eaeb13c4b17 100644
--- a/lib/gitlab/import/github/client.rb
+++ b/lib/gitlab/import/github/client.rb
@@ -10,13 +10,18 @@ def initialize(project)
         end
 
         def labels
-          request { client.labels(repo, per_page: 100) }
+          request { client.labels(repo, per_page: PER_PAGE) }
+        end
+
+        def milestones
+          client.milestones(repo, state: :all, per_page: PER_PAGE)
         end
 
         private
 
         attr_reader :credentials, :options, :repo, :repo_url
 
+        PER_PAGE = 100
         SAFE_REMAINING_REQUESTS = 100
         SAFE_SLEEP_TIME = 500
 
diff --git a/lib/gitlab/import/github/mapper/label.rb b/lib/gitlab/import/github/mapper/label.rb
index 6e2f4cb99a97..57c0cc358105 100644
--- a/lib/gitlab/import/github/mapper/label.rb
+++ b/lib/gitlab/import/github/mapper/label.rb
@@ -9,6 +9,8 @@ def initialize(project, client)
           end
 
           def each
+            return enum_for(:each) unless block_given?
+
             client.labels.each do |raw|
               label = ::Label.new(
                 project: project,
diff --git a/lib/gitlab/import/github/mapper/milestone.rb b/lib/gitlab/import/github/mapper/milestone.rb
new file mode 100644
index 000000000000..a675defdbe92
--- /dev/null
+++ b/lib/gitlab/import/github/mapper/milestone.rb
@@ -0,0 +1,37 @@
+module Gitlab
+  module Import
+    module Github
+      module Mapper
+        class Milestone
+          def initialize(project, client)
+            @project = project
+            @client  = client
+          end
+
+          def each
+            return enum_for(:each) unless block_given?
+
+            client.milestones.each do |raw|
+              milestone = ::Milestone.new(
+                iid: raw.number,
+                project: project,
+                title: raw.title,
+                description: raw.description,
+                due_date: raw.due_on,
+                state: raw.state == 'closed' ? 'closed' : 'active',
+                created_at: raw.created_at,
+                updated_at: raw.state == 'closed' ? raw.closed_at : raw.updated_at
+              )
+
+              yield(milestone)
+            end
+          end
+
+          private
+
+          attr_reader :project, :client
+        end
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/import/github/mapper/milestone_spec.rb b/spec/lib/gitlab/import/github/mapper/milestone_spec.rb
new file mode 100644
index 000000000000..9ebcf7814244
--- /dev/null
+++ b/spec/lib/gitlab/import/github/mapper/milestone_spec.rb
@@ -0,0 +1,72 @@
+require 'spec_helper'
+
+describe Gitlab::Import::Github::Mapper::Milestone, lib: true do
+  let(:project) { create(:empty_project) }
+  let(:client)  { double(milestones: response) }
+
+  let(:response) do
+    [
+      double(
+        number: 2,
+        state: 'open',
+        title: 'v2.0',
+        description: 'Tracking milestone for version 2.0',
+        created_at: '2011-04-10T20:09:31Z',
+        updated_at: '2014-03-03T18:58:10Z',
+        closed_at: nil,
+        due_on: '2012-10-09T23:39:01Z'
+      ),
+      double(
+        number: 1,
+        state: 'closed',
+        title: 'v1.0',
+        description: 'Tracking milestone for version 1.0',
+        created_at: '2011-04-10T20:09:31Z',
+        updated_at: '2014-03-03T18:58:10Z',
+        closed_at: '2012-10-09T23:39:01Z',
+        due_on: nil
+      )
+    ]
+  end
+
+  subject(:mapper) { described_class.new(project, client) }
+
+  describe '#each' do
+    it 'yields successively with Milestone' do
+      expect { |block| mapper.each(&block) }.to yield_successive_args(Milestone, Milestone)
+    end
+
+    it 'matches the Milestone attributes' do
+      milestone_opened = {
+        project: project,
+        iid: 2,
+        title: 'v2.0',
+        description: 'Tracking milestone for version 2.0',
+        state: 'active',
+        due_date: DateTime.strptime('2012-10-09T23:39:01Z'),
+        created_at: DateTime.strptime('2011-04-10T20:09:31Z'),
+        updated_at: DateTime.strptime('2014-03-03T18:58:10Z')
+      }
+
+      milestone_closed = {
+        project: project,
+        iid: 1,
+        title: 'v1.0',
+        description: 'Tracking milestone for version 1.0',
+        state: 'closed',
+        due_date: nil,
+        created_at: DateTime.strptime('2011-04-10T20:09:31Z'),
+        updated_at: DateTime.strptime('2012-10-09T23:39:01Z')
+      }
+
+      expected = [
+        milestone_opened,
+        milestone_closed
+      ]
+
+      mapper.each.with_index do |milestone, index|
+        expect(milestone).to have_attributes(expected[index])
+      end
+    end
+  end
+end
-- 
GitLab


From 8f3b6591ccc1dcebb0e4ae1e3cf44588b2a4afe8 Mon Sep 17 00:00:00 2001
From: Douglas Barbosa Alexandre <dbalexandre@gmail.com>
Date: Fri, 8 Jul 2016 18:06:02 -0300
Subject: [PATCH 6/6] Extract base mapper

---
 lib/gitlab/import/github/mapper/base.rb       | 37 +++++++++++++++++
 lib/gitlab/import/github/mapper/label.rb      | 31 +++++---------
 lib/gitlab/import/github/mapper/milestone.rb  | 41 ++++++++-----------
 .../gitlab/import/github/mapper/base_spec.rb  | 19 +++++++++
 .../gitlab/import/github/mapper/label_spec.rb |  2 +-
 .../import/github/mapper/milestone_spec.rb    |  2 +-
 6 files changed, 85 insertions(+), 47 deletions(-)
 create mode 100644 lib/gitlab/import/github/mapper/base.rb
 create mode 100644 spec/lib/gitlab/import/github/mapper/base_spec.rb

diff --git a/lib/gitlab/import/github/mapper/base.rb b/lib/gitlab/import/github/mapper/base.rb
new file mode 100644
index 000000000000..78e8b97eb03a
--- /dev/null
+++ b/lib/gitlab/import/github/mapper/base.rb
@@ -0,0 +1,37 @@
+module Gitlab
+  module Import
+    module Github
+      module Mapper
+        class Base
+          def initialize(project, client)
+            @project = project
+            @client  = client
+          end
+
+          def each
+            return enum_for(:each) unless block_given?
+
+            method = klass.to_s.underscore.pluralize
+
+            client.public_send(method).each do |raw|
+              yield(klass.new(attributes_for(raw)))
+            end
+          end
+
+          private
+
+          attr_reader :project, :client
+
+          def attributes_for
+            {}
+          end
+
+          def klass
+            raise NotImplementedError,
+              "#{self.class} does not implement #{__method__}"
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/import/github/mapper/label.rb b/lib/gitlab/import/github/mapper/label.rb
index 57c0cc358105..4a56a190d18e 100644
--- a/lib/gitlab/import/github/mapper/label.rb
+++ b/lib/gitlab/import/github/mapper/label.rb
@@ -2,29 +2,20 @@ module Gitlab
   module Import
     module Github
       module Mapper
-        class Label
-          def initialize(project, client)
-            @project = project
-            @client  = client
-          end
-
-          def each
-            return enum_for(:each) unless block_given?
-
-            client.labels.each do |raw|
-              label = ::Label.new(
-                project: project,
-                title: raw.name,
-                color: "##{raw.color}"
-              )
+        class Label < Base
+          private
 
-              yield(label)
-            end
+          def attributes_for(raw)
+            {
+              project: project,
+              title: raw.name,
+              color: "##{raw.color}"
+            }
           end
 
-          private
-
-          attr_reader :project, :client
+          def klass
+            ::Label
+          end
         end
       end
     end
diff --git a/lib/gitlab/import/github/mapper/milestone.rb b/lib/gitlab/import/github/mapper/milestone.rb
index a675defdbe92..4d6e8454c55d 100644
--- a/lib/gitlab/import/github/mapper/milestone.rb
+++ b/lib/gitlab/import/github/mapper/milestone.rb
@@ -2,34 +2,25 @@ module Gitlab
   module Import
     module Github
       module Mapper
-        class Milestone
-          def initialize(project, client)
-            @project = project
-            @client  = client
-          end
-
-          def each
-            return enum_for(:each) unless block_given?
-
-            client.milestones.each do |raw|
-              milestone = ::Milestone.new(
-                iid: raw.number,
-                project: project,
-                title: raw.title,
-                description: raw.description,
-                due_date: raw.due_on,
-                state: raw.state == 'closed' ? 'closed' : 'active',
-                created_at: raw.created_at,
-                updated_at: raw.state == 'closed' ? raw.closed_at : raw.updated_at
-              )
+        class Milestone < Base
+          private
 
-              yield(milestone)
-            end
+          def attributes_for(raw)
+            {
+              iid: raw.number,
+              project: project,
+              title: raw.title,
+              description: raw.description,
+              due_date: raw.due_on,
+              state: raw.state == 'closed' ? 'closed' : 'active',
+              created_at: raw.created_at,
+              updated_at: raw.state == 'closed' ? raw.closed_at : raw.updated_at
+            }
           end
 
-          private
-
-          attr_reader :project, :client
+          def klass
+            ::Milestone
+          end
         end
       end
     end
diff --git a/spec/lib/gitlab/import/github/mapper/base_spec.rb b/spec/lib/gitlab/import/github/mapper/base_spec.rb
new file mode 100644
index 000000000000..f3d823b19f20
--- /dev/null
+++ b/spec/lib/gitlab/import/github/mapper/base_spec.rb
@@ -0,0 +1,19 @@
+require 'spec_helper'
+
+describe Gitlab::Import::Github::Mapper::Base, lib: true do
+  let(:project) { double }
+  let(:client)  { double }
+
+  subject(:mapper) do
+    klass = Class.new(described_class)
+    klass.new(project, client)
+  end
+
+  describe '#each' do
+    context 'when klass is not implemented' do
+      it 'raises NotImplementedError' do
+        expect { mapper.each(&:to_s) }.to raise_error(NotImplementedError)
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/import/github/mapper/label_spec.rb b/spec/lib/gitlab/import/github/mapper/label_spec.rb
index c02758cda442..94d810ef9f92 100644
--- a/spec/lib/gitlab/import/github/mapper/label_spec.rb
+++ b/spec/lib/gitlab/import/github/mapper/label_spec.rb
@@ -1,7 +1,7 @@
 require 'spec_helper'
 
 describe Gitlab::Import::Github::Mapper::Label, lib: true do
-  let(:project) { create(:empty_project) }
+  let(:project) { build(:empty_project) }
   let(:client)  { double(labels: response) }
 
   let(:response) do
diff --git a/spec/lib/gitlab/import/github/mapper/milestone_spec.rb b/spec/lib/gitlab/import/github/mapper/milestone_spec.rb
index 9ebcf7814244..ea580771bf79 100644
--- a/spec/lib/gitlab/import/github/mapper/milestone_spec.rb
+++ b/spec/lib/gitlab/import/github/mapper/milestone_spec.rb
@@ -1,7 +1,7 @@
 require 'spec_helper'
 
 describe Gitlab::Import::Github::Mapper::Milestone, lib: true do
-  let(:project) { create(:empty_project) }
+  let(:project) { build(:empty_project) }
   let(:client)  { double(milestones: response) }
 
   let(:response) do
-- 
GitLab