diff --git a/spec/v3/services/build/cancel_spec.rb b/spec/v3/services/build/cancel_spec.rb
new file mode 100644
index 00000000..28838370
--- /dev/null
+++ b/spec/v3/services/build/cancel_spec.rb
@@ -0,0 +1,167 @@
+require 'spec_helper'
+
+describe Travis::API::V3::Services::Build::Cancel do
+  let(:repo) { Travis::API::V3::Models::Repository.where(owner_name: 'svenfuchs', name: 'minimal').first }
+  let(:build) { repo.builds.first }
+  let(:sidekiq_payload) { JSON.load(Sidekiq::Client.last['args'].last[:payload]).deep_symbolize_keys }
+  let(:sidekiq_params) { Sidekiq::Client.last['args'].last.deep_symbolize_keys }
+  # before { build.cancel.each(&:delete) }
+
+  before do
+    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/build/#{build.id}/cancel")      }
+    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 build, authenticated" do
+    let(:token)   { Travis::Api::App::AccessToken.create(user: repo.owner, app_id: 1) }
+    let(:headers) {{ 'HTTP_AUTHORIZATION' => "token #{token}"                        }}
+    before        { post("/v3/build/9999999999/cancel", {}, headers)                 }
+
+    example { expect(last_response.status).to be == 404 }
+    example { expect(JSON.load(body)).to      be ==     {
+      "@type"         => "error",
+      "error_type"    => "not_found",
+      "error_message" => "build not found (or insufficient access)",
+      "resource_type" => "build"
+    }}
+  end
+
+  describe "existing repository, no push access" do
+    let(:token)   { Travis::Api::App::AccessToken.create(user: repo.owner, app_id: 1) }
+    let(:headers) {{ 'HTTP_AUTHORIZATION' => "token #{token}"                        }}
+    before        { post("/v3/build/#{build.id}/cancel", {}, headers)                 }
+
+    example { expect(last_response.status).to be == 403 }
+    example { expect(JSON.load(body).to_s).to include(
+      "@type",
+      "error_type",
+      "error_message",
+      "insufficient access",
+      "resource_type",
+      "build",
+      "permission",
+      "build_cancellation")
+    }
+  end
+
+  describe "private repository, no access" do
+    let(:token)   { Travis::Api::App::AccessToken.create(user: repo.owner, app_id: 1) }
+    let(:headers) {{ 'HTTP_AUTHORIZATION' => "token #{token}"                        }}
+    before        { repo.update_attribute(:private, true)                             }
+    before        { post("/v3/build/#{build.id}/cancel", {}, headers)                 }
+    after         { build.update_attribute(:private, false)                            }
+
+    example { expect(last_response.status).to be == 404 }
+    example { expect(JSON.load(body)).to      be ==     {
+      "@type"         => "error",
+      "error_type"    => "not_found",
+      "error_message" => "build not found (or insufficient access)",
+      "resource_type" => "build"
+    }}
+  end
+
+  describe "existing repository, push access" do
+    let(:params)  {{}}
+    let(:token)   { Travis::Api::App::AccessToken.create(user: repo.owner, app_id: 1)                          }
+    let(:headers) {{ 'HTTP_AUTHORIZATION' => "token #{token}"                                                 }}
+    before        { Travis::API::V3::Models::Permission.create(repository: repo, user: repo.owner, push: true) }
+    before        { post("/v3/build/#{build.id}/cancel", params, headers)                                      }
+
+    example { expect(last_response.status).to be == 202 }
+    example { expect(JSON.load(body).to_s).to include(
+      "@type",
+      "pending",
+      "build",
+      "@href",
+      "@representation",
+      "minimal",
+      "request",
+      "user",
+      "resource_type",
+      "request")
+    }
+
+    example { expect(sidekiq_payload).to be == {
+      build:      { id: build.id }
+    }}
+
+    example { expect(Sidekiq::Client.last['queue']).to be == 'build_cancellations'                }
+    example { expect(Sidekiq::Client.last['class']).to be == 'Travis::Sidekiq::CancellationRequest' }
+
+    describe "setting id has no effect" do
+      let(:params) {{ id: 42 }}
+      example { expect(sidekiq_payload).to be == {
+        build:      { id: build.id }
+      }}
+    end
+
+    describe "passing the token in params" do
+      let(:params) {{ request: { token: 'foo-bar' }}}
+      example { expect(sidekiq_params[:credentials]).to be == {
+        token: 'foo-bar'
+      }}
+    end
+  end
+
+
+  describe "existing repository, application with full access" do
+    let(:app_name)   { 'travis-example'                                                           }
+    let(:app_secret) { '12345678'                                                                 }
+    let(:sign_opts)  { "a=#{app_name}"                                                            }
+    let(:signature)  { OpenSSL::HMAC.hexdigest('sha256', app_secret, sign_opts)                   }
+    let(:headers)    {{ 'HTTP_AUTHORIZATION' => "signature #{sign_opts}:#{signature}"            }}
+    before { Travis.config.applications = { app_name => { full_access: true, secret: app_secret }}}
+    before { post("/v3/build/#{build.id}/cancel", params, headers)                                }
+
+    # describe 'without setting user' do
+    #   let(:params) {{}}
+    #   example { expect(last_response.status).to be == 400 }
+    #   example { expect(JSON.load(body)).to      be ==     {
+    #     "@type"         => "error",
+    #     "error_type"    => "wrong_params",
+    #     "error_message" => "missing user"
+    #   }}
+    # end
+    #
+    # describe 'setting user' do
+    #   let(:params) {{ user: { id: repo.owner.id } }}
+    #   example { expect(last_response.status).to be == 202 }
+    #   example { expect(sidekiq_payload).to be == {
+    #     repository: { id: repo.id, owner_name: 'svenfuchs', name: 'minimal' },
+    #     user:       { id: repo.owner.id },
+    #     message:    nil,
+    #     branch:     'master',
+    #     config:     {}
+    #   }}
+    # end
+    #
+    # describe 'setting branch' do
+    #   let(:params) {{ user: { id: repo.owner.id }, branch: 'example' }}
+    #   example { expect(last_response.status).to be == 202 }
+    #   example { expect(sidekiq_payload).to be == {
+    #     repository: { id: repo.id, owner_name: 'svenfuchs', name: 'minimal' },
+    #     user:       { id: repo.owner.id },
+    #     message:    nil,
+    #     branch:     'example',
+    #     config:     {}
+    #   }}
+    # end
+  end
+end