func (s *lxcBrokerSuite) TestDiscoverPrimaryNICInterfaceNotFound(c *gc.C) {
	s.PatchValue(provisioner.NetInterfaces, func() ([]net.Interface, error) {
		return nil, nil
	})

	nic, addr, err := provisioner.DiscoverPrimaryNIC()
	c.Assert(err, gc.ErrorMatches, "cannot detect the primary network interface")
	c.Assert(nic, gc.Equals, "")
	c.Assert(addr, jc.DeepEquals, network.Address{})
}

func (s *lxcBrokerSuite) TestDiscoverPrimaryNICNetInterfacesError(c *gc.C) {
	s.PatchValue(provisioner.NetInterfaces, func() ([]net.Interface, error) {
		return nil, errors.New("boom!")
	})

	nic, addr, err := provisioner.DiscoverPrimaryNIC()
	c.Assert(err, gc.ErrorMatches, "cannot get network interfaces: boom!")
	c.Assert(nic, gc.Equals, "")
	c.Assert(addr, jc.DeepEquals, network.Address{})
}

func (s *lxcBrokerSuite) TestDiscoverPrimaryNICInvalidAddr(c *gc.C) {
	s.PatchValue(provisioner.NetInterfaces, func() ([]net.Interface, error) {
		return []net.Interface{{
			Index: 0,
			Name:  "fake",
			Flags: net.FlagUp,
		}}, nil
	})
	s.PatchValue(provisioner.InterfaceAddrs, func(i *net.Interface) ([]net.Addr, error) {
		return []net.Addr{&fakeAddr{}}, nil
	})

	nic, addr, err := provisioner.DiscoverPrimaryNIC()
	c.Assert(err, gc.ErrorMatches, `cannot parse address "fakeAddr": invalid CIDR address: fakeAddr`)
	c.Assert(nic, gc.Equals, "")
	c.Assert(addr, jc.DeepEquals, network.Address{})
}

func (s *lxcBrokerSuite) TestDiscoverPrimaryNICInterfaceAddrsError(c *gc.C) {
	s.PatchValue(provisioner.NetInterfaces, func() ([]net.Interface, error) {
		return []net.Interface{{
			Index: 0,
			Name:  "fake",
			Flags: net.FlagUp,
		}}, nil
	})
	s.PatchValue(provisioner.InterfaceAddrs, func(i *net.Interface) ([]net.Addr, error) {
		return nil, errors.New("boom!")
	})

	nic, addr, err := provisioner.DiscoverPrimaryNIC()
	c.Assert(err, gc.ErrorMatches, `cannot get "fake" addresses: boom!`)
	c.Assert(nic, gc.Equals, "")
	c.Assert(addr, jc.DeepEquals, network.Address{})
}

func (s *lxcBrokerSuite) TestDiscoverPrimaryNICSuccess(c *gc.C) {
	s.PatchValue(provisioner.NetInterfaces, func() ([]net.Interface, error) {
		return []net.Interface{{
			Index: 0,
			Name:  "lo",
			Flags: net.FlagUp | net.FlagLoopback, // up but loopback - ignored.
		}, {
			Index: 1,
			Name:  "if0",
			Flags: net.FlagPointToPoint, // not up - ignored.
		}, {
			Index: 2,
			Name:  "if1",
			Flags: net.FlagUp, // up but no addresses - ignored.
		}, {
			Index: 3,
			Name:  "if2",
			Flags: net.FlagUp, // up and has addresses - returned.
		}}, nil
	})
	s.PatchValue(provisioner.InterfaceAddrs, func(i *net.Interface) ([]net.Addr, error) {
		// We should be called only for the last two NICs. The first
		// one (if1) won't have addresses, only the last one (if2).
		c.Assert(i, gc.NotNil)
		c.Assert(i.Name, gc.Matches, "if[12]")
		if i.Name == "if2" {
			return []net.Addr{&fakeAddr{"0.1.2.3/24"}}, nil
		}
		// For if1 we return no addresses.
		return nil, nil
	})

	nic, addr, err := provisioner.DiscoverPrimaryNIC()
	c.Assert(err, jc.ErrorIsNil)
	c.Assert(nic, gc.Equals, "if2")
	c.Assert(addr, jc.DeepEquals, network.NewAddress("0.1.2.3"))
}