link netlink.Link address *net.IPNet ) BeforeEach(func() { var err error link = &netlink.Veth{} _, address, err = net.ParseCIDR("192.168.1.1/24") Expect(err).NotTo(HaveOccurred()) }) It("adds an address to the link", func() { err := addressManager.AddAddress(link, address) Expect(err).NotTo(HaveOccurred()) Expect(netlinker.AddrAddCallCount()).To(Equal(1)) actualLink, netlinkAddr := netlinker.AddrAddArgsForCall(0) Expect(actualLink).To(Equal(link)) Expect(netlinkAddr.IPNet).To(Equal(address)) }) Context("when adding the addres fails", func() { BeforeEach(func() { netlinker.AddrAddReturns(errors.New("adding address failed")) }) It("returns the error", func() { err := addressManager.AddAddress(link, address) Expect(err).To(MatchError("adding address failed")) })