diff --git a/spec/v3/services/user/sync_spec.rb b/spec/v3/services/user/sync_spec.rb
new file mode 100644
index 00000000..d422cb22
--- /dev/null
+++ b/spec/v3/services/user/sync_spec.rb
@@ -0,0 +1,110 @@
+require 'spec_helper'
+
+describe Travis::API::V3::Services::User::Sync do
+  let(:user)  { Travis::API::V3::Models::User.find_by_login('svenfuchs') }
+  let(:user2) { Travis::API::V3::Models::User.create(login: 'carlad', is_syncing: true) }
+  let(:sidekiq_payload) { JSON.load(Sidekiq::Client.last['args'].last.to_json) }
+  let(:sidekiq_params)  { Sidekiq::Client.last['args'].last.deep_symbolize_keys }
+
+  before do
+    user.update_attribute(:is_syncing, false)
+    Travis::Features.stubs(:owner_active?).returns(true)
+    @original_sidekiq = Sidekiq::Client
+    Sidekiq.send(:remove_const, :Client) # to avoid a warning
+    Sidekiq::Client = []
+  end
+
+  after do
+    Sidekiq.send(:remove_const, :Client) # to avoid a warning
+    Sidekiq::Client = @original_sidekiq
+  end
+
+  describe "not authenticated" do
+    before  { post("/v3/user/#{user.id}/sync") }
+    example { expect(last_response.status).to be == 403 }
+    example { expect(JSON.load(body)).to      be ==     {
+      "@type"         => "error",
+      "error_type"    => "login_required",
+      "error_message" => "login required"
+    }}
+  end
+
+  describe "missing user, authenticated" do
+    let(:token)   { Travis::Api::App::AccessToken.create(user: user, app_id: 1) }
+    let(:headers) {{ 'HTTP_AUTHORIZATION' => "token #{token}" }}
+    before        { post("/v3/user/9999999999/sync", {}, headers) }
+
+    example { expect(last_response.status).to be == 404 }
+    example { expect(JSON.load(body)).to      be ==     {
+      "@type"         => "error",
+      "error_type"    => "not_found",
+      "error_message" => "user not found (or insufficient access)",
+      "resource_type" => "user"
+    }}
+  end
+
+  describe "existing user, matches current user " do
+    let(:params)  {{}}
+    let(:token)   { Travis::Api::App::AccessToken.create(user: user, app_id: 1) }
+    let(:headers) {{ 'HTTP_AUTHORIZATION' => "token #{token}" }}
+    before        { Travis::API::V3::Models::Permission.create(user: user) }
+    before        { post("/v3/user/#{user.id}/sync", params, headers) }
+
+    example { expect(last_response.status).to be == 200 }
+    example { expect(JSON.load(body).to_s).to include(
+      "@type",
+      "user",
+      "@href",
+      "@representation",
+      "sync",
+      "is_syncing",
+      "id",
+      "true")
+    }
+
+    example { expect(sidekiq_payload).to be == user.id }
+
+    example { expect(Sidekiq::Client.last['queue']).to be == 'user_syncs'                }
+    example { expect(Sidekiq::Client.last['class']).to be == 'Travis::Sidekiq::UserSync' }
+  end
+
+  describe "existing user, current user does not have sync access " do
+    let(:params)  {{}}
+    let(:token)   { Travis::Api::App::AccessToken.create(user: user, app_id: 1) }
+    let(:headers) {{ 'HTTP_AUTHORIZATION' => "token #{token}" }}
+    before        { Travis::API::V3::Models::Permission.create(user: user) }
+    before        { post("/v3/user/#{user2.id}/sync", params, headers) }
+
+    example { expect(last_response.status).to be == 403 }
+    example { expect(JSON.load(body)).to be == {
+      "@type"         => "error",
+      "error_type"    => "insufficient_access",
+      "error_message" => "operation requires sync access to user",
+      "resource_type" => "user",
+      "permission"    => "sync",
+      "user"          => {
+        "@type"       => "user",
+        "@href"       => "/user/#{user2.id}",
+        "@representation"=> "minimal",
+        "id"          => user2.id,
+        "login"       => "carlad"
+      }
+    }}
+  end
+
+  describe "existing user, authorized, user already syncing " do
+    let(:params)  {{}}
+    let(:token)   { Travis::Api::App::AccessToken.create(user: user2, app_id: 1) }
+    let(:headers) {{ 'HTTP_AUTHORIZATION' => "token #{token}" }}
+    before        { Travis::API::V3::Models::Permission.create(user: user) }
+    before        { post("/v3/user/#{user2.id}/sync", params, headers) }
+
+    example { expect(last_response.status).to be == 409 }
+    example { expect(JSON.load(body)).to be == {
+      "@type"         => "error",
+      "error_type"    => "already_syncing",
+      "error_message" => "sync already in progress"
+      }
+    }
+  end
+end