add memberships endpoint

lib/gitlab/client/users.rb

@@ -486,6 +486,16 @@ def revoke_user_impersonation_token(user_id, impersonation_token_id)
       delete("/users/#{user_id}/impersonation_tokens/#{impersonation_token_id}")
     end
 
+    # Lists all projects and groups a user is a member of
+    #
+    # @example
+    #   Gitlab.memberships(2)
+    #
+    # @param  [Integer] user_id The ID of the user.
+    def memberships(user_id)
+      get("/users/#{user_id}/memberships")
+    end
+
     # Revoke a personal access token
     #
     # @example

spec/fixtures/memberships.json

@@ -0,0 +1 @@
+[{"source_id": 1,"source_name": "Project one","source_type": "Project","access_level": "20"},{"source_id": 3,"source_name": "Group three","source_type": "Namespace","access_level": "20"}]

spec/gitlab/client/users_spec.rb

@@ -718,6 +718,24 @@
     end
   end
 
+  describe '.memberships' do
+    before do
+      stub_get('/user/2/memberships', 'memberships')
+      @memberships = Gitlab.memberships(2)
+    end
+
+    it 'gets the correct resource' do
+      expect(a_get('/user/2/memberships')).to have_been_made
+    end
+
+    it 'returns an information about all project and groups of user' do
+      expect(@memberships.first.source_id).to eq 1
+      expect(@memberships.first.source_name).to eq 'Project one'
+      expect(@memberships.first.source_type).to eq 'Project'
+      expect(@memberships.first.access_level).to eq 20
+    end
+  end
+
   describe 'get all personal access tokens' do
     describe 'get all' do
       before do