func (s *relationUnitSuite) TestWatchRelationUnits(c *gc.C) {
	// Enter scope with mysqlUnit.
	myRelUnit, err := s.stateRelation.Unit(s.mysqlUnit)
	c.Assert(err, gc.IsNil)
	err = myRelUnit.EnterScope(nil)
	c.Assert(err, gc.IsNil)
	s.assertInScope(c, myRelUnit, true)

	apiRel, err := s.uniter.Relation(s.stateRelation.Tag().String())
	c.Assert(err, gc.IsNil)
	apiUnit, err := s.uniter.Unit(names.NewUnitTag("wordpress/0"))
	c.Assert(err, gc.IsNil)
	apiRelUnit, err := apiRel.Unit(apiUnit)
	c.Assert(err, gc.IsNil)

	w, err := apiRelUnit.Watch()
	defer statetesting.AssertStop(c, w)
	wc := statetesting.NewRelationUnitsWatcherC(c, s.BackingState, w)

	// Initial event.
	wc.AssertChange([]string{"mysql/0"}, nil)

	// Leave scope with mysqlUnit, check it's detected.
	err = myRelUnit.LeaveScope()
	c.Assert(err, gc.IsNil)
	s.assertInScope(c, myRelUnit, false)
	wc.AssertChange(nil, []string{"mysql/0"})

	// Non-change is not reported.
	err = myRelUnit.LeaveScope()
	c.Assert(err, gc.IsNil)
	wc.AssertNoChange()

	// NOTE: This test is not as exhaustive as the one in state,
	// because the watcher is already tested there. Here we just
	// ensure we get the events when we expect them and don't get
	// them when they're not expected.

	statetesting.AssertStop(c, w)
	wc.AssertClosed()
}

func (s *WatchScopeSuite) TestProviderRequirerGlobal(c *gc.C) {
	// Create a pair of services and a relation between them.
	mysql := s.AddTestingService(c, "mysql", s.AddTestingCharm(c, "mysql"))
	mysqlEP, err := mysql.Endpoint("server")
	c.Assert(err, jc.ErrorIsNil)
	wordpress := s.AddTestingService(c, "wordpress", s.AddTestingCharm(c, "wordpress"))
	wordpressEP, err := wordpress.Endpoint("db")
	c.Assert(err, jc.ErrorIsNil)
	rel, err := s.State.AddRelation(mysqlEP, wordpressEP)
	c.Assert(err, jc.ErrorIsNil)

	// Add some units to the services and set their private addresses.
	addUnit := func(srv *state.Service, sub string, ep state.Endpoint) *state.RelationUnit {
		unit, err := srv.AddUnit()
		c.Assert(err, jc.ErrorIsNil)
		ru, err := rel.Unit(unit)
		c.Assert(err, jc.ErrorIsNil)
		c.Assert(ru.Endpoint(), gc.Equals, ep)
		return ru
	}
	msru0 := addUnit(mysql, "ms0", mysqlEP)
	msru1 := addUnit(mysql, "ms1", mysqlEP)
	wpru0 := addUnit(wordpress, "wp0", wordpressEP)
	wpru1 := addUnit(wordpress, "wp1", wordpressEP)

	// ---------- Single role active ----------

	// Watch the relation from the perspective of the first provider unit and
	// check initial event.
	msw0 := msru0.Watch()
	defer testing.AssertStop(c, msw0)
	msw0c := testing.NewRelationUnitsWatcherC(c, s.State, msw0)
	msw0c.AssertChange(nil, nil)
	msw0c.AssertNoChange()

	// Join the unit to the relation, change its settings, and check that
	// nothing apparently happens.
	err = msru0.EnterScope(nil)
	c.Assert(err, jc.ErrorIsNil)
	changeSettings(c, msru0)
	msw0c.AssertNoChange()

	// Join the second provider unit, start its watch, and check what it thinks the
	// state of the relation is.
	err = msru1.EnterScope(nil)
	c.Assert(err, jc.ErrorIsNil)
	msw1 := msru1.Watch()
	defer testing.AssertStop(c, msw1)
	msw1c := testing.NewRelationUnitsWatcherC(c, s.State, msw1)
	msw1c.AssertChange(nil, nil)
	msw1c.AssertNoChange()

	// Change the unit's settings, and check that neither provider unit
	// observes any change.
	changeSettings(c, msru1)
	msw1c.AssertNoChange()
	msw0c.AssertNoChange()

	// ---------- Two roles active ----------

	// Start watches from both requirer units' perspectives, and check that
	// they see the provider units.
	expectChanged := []string{"mysql/0", "mysql/1"}
	wpw0 := wpru0.Watch()
	defer testing.AssertStop(c, wpw0)
	wpw0c := testing.NewRelationUnitsWatcherC(c, s.State, wpw0)
	wpw0c.AssertChange(expectChanged, nil)
	wpw0c.AssertNoChange()
	wpw1 := wpru1.Watch()
	defer testing.AssertStop(c, wpw1)
	wpw1c := testing.NewRelationUnitsWatcherC(c, s.State, wpw1)
	wpw1c.AssertChange(expectChanged, nil)
	wpw1c.AssertNoChange()

	// Join the first requirer unit, and check the provider units see it.
	err = wpru0.EnterScope(nil)
	c.Assert(err, jc.ErrorIsNil)
	expectChanged = []string{"wordpress/0"}
	msw0c.AssertChange(expectChanged, nil)
	msw0c.AssertNoChange()
	msw1c.AssertChange(expectChanged, nil)
	msw1c.AssertNoChange()

	// Join again, check no-op.
	err = wpru0.EnterScope(nil)
	c.Assert(err, jc.ErrorIsNil)
	msw0c.AssertNoChange()
	msw1c.AssertNoChange()

	// Join the second requirer, and check the provider units see the change.
	err = wpru1.EnterScope(nil)
	c.Assert(err, jc.ErrorIsNil)
	expectChanged = []string{"wordpress/1"}
	msw0c.AssertChange(expectChanged, nil)
	msw0c.AssertNoChange()
	msw1c.AssertChange(expectChanged, nil)
	msw1c.AssertNoChange()

	// Verify that neither requirer has observed any change to the relation.
	wpw0c.AssertNoChange()
//.........这里部分代码省略.........

func (s *WatchScopeSuite) TestPeer(c *gc.C) {
	// Create a service and get a peer relation.
	riak := s.AddTestingService(c, "riak", s.AddTestingCharm(c, "riak"))
	riakEP, err := riak.Endpoint("ring")
	c.Assert(err, jc.ErrorIsNil)
	rels, err := riak.Relations()
	c.Assert(err, jc.ErrorIsNil)
	c.Assert(rels, gc.HasLen, 1)
	rel := rels[0]

	// Add some units to the service and set their private addresses; get
	// the relevant RelationUnits.
	// (Private addresses should be set by their unit agents on
	// startup; this test does not include that, but Join expects
	// the information to be available, and uses it to populate the
	// relation settings node.)
	addUnit := func(i int) *state.RelationUnit {
		unit, err := riak.AddUnit()
		c.Assert(err, jc.ErrorIsNil)
		err = unit.AssignToNewMachine()
		c.Assert(err, jc.ErrorIsNil)
		mId, err := unit.AssignedMachineId()
		c.Assert(err, jc.ErrorIsNil)
		machine, err := s.State.Machine(mId)
		c.Assert(err, jc.ErrorIsNil)
		privateAddr := network.NewScopedAddress(
			fmt.Sprintf("riak%d.example.com", i),
			network.ScopeCloudLocal,
		)
		machine.SetProviderAddresses(privateAddr)
		ru, err := rel.Unit(unit)
		c.Assert(err, jc.ErrorIsNil)
		c.Assert(ru.Endpoint(), gc.Equals, riakEP)
		return ru
	}
	ru0 := addUnit(0)
	ru1 := addUnit(1)
	ru2 := addUnit(2)

	// ---------- Single unit ----------

	// Start watching the relation from the perspective of the first unit.
	w0 := ru0.Watch()
	defer testing.AssertStop(c, w0)
	w0c := testing.NewRelationUnitsWatcherC(c, s.State, w0)
	w0c.AssertChange(nil, nil)
	w0c.AssertNoChange()

	// Join the first unit to the relation, and change the settings, and
	// check that nothing apparently happens.
	err = ru0.EnterScope(nil)
	c.Assert(err, jc.ErrorIsNil)
	changeSettings(c, ru0)
	w0c.AssertNoChange()

	// ---------- Two units ----------

	// Now join another unit to the relation...
	err = ru1.EnterScope(nil)
	c.Assert(err, jc.ErrorIsNil)

	// ...and check that the first relation unit sees the change.
	expectChanged := []string{"riak/1"}
	w0c.AssertChange(expectChanged, nil)
	w0c.AssertNoChange()

	// Join again, check it's a no-op.
	err = ru1.EnterScope(nil)
	c.Assert(err, jc.ErrorIsNil)
	w0c.AssertNoChange()

	// Start watching the relation from the perspective of the second unit,
	// and check that it sees the right state.
	w1 := ru1.Watch()
	defer testing.AssertStop(c, w1)
	w1c := testing.NewRelationUnitsWatcherC(c, s.State, w1)
	expectChanged = []string{"riak/0"}
	w1c.AssertChange(expectChanged, nil)
	w1c.AssertNoChange()

	// ---------- Three units ----------

	// Whoa, it works. Ok, check the third unit's opinion of the state.
	w2 := ru2.Watch()
	defer testing.AssertStop(c, w2)
	w2c := testing.NewRelationUnitsWatcherC(c, s.State, w2)
	expectChanged = []string{"riak/0", "riak/1"}
	w2c.AssertChange(expectChanged, nil)
	w2c.AssertNoChange()

	// Join the third unit, and check the first and second units see it.
	err = ru2.EnterScope(nil)
	c.Assert(err, jc.ErrorIsNil)
	expectChanged = []string{"riak/2"}
	w0c.AssertChange(expectChanged, nil)
	w0c.AssertNoChange()
	w1c.AssertChange(expectChanged, nil)
	w1c.AssertNoChange()

	// Change the second unit's settings, and check that only
//.........这里部分代码省略.........

func (s *WatchScopeSuite) TestProviderRequirerContainer(c *gc.C) {
	// Create a pair of services and a relation between them.
	mysql := s.AddTestingService(c, "mysql", s.AddTestingCharm(c, "mysql"))
	mysqlEP, err := mysql.Endpoint("juju-info")
	c.Assert(err, jc.ErrorIsNil)
	logging := s.AddTestingService(c, "logging", s.AddTestingCharm(c, "logging"))
	loggingEP, err := logging.Endpoint("info")
	c.Assert(err, jc.ErrorIsNil)
	rel, err := s.State.AddRelation(mysqlEP, loggingEP)
	c.Assert(err, jc.ErrorIsNil)

	// Change mysqlEP to match the endpoint that will actually be used by the relation.
	mysqlEP.Scope = charm.ScopeContainer

	// Add some units to the services and set their private addresses.
	addUnits := func(i int) (*state.RelationUnit, *state.RelationUnit) {
		msu, err := mysql.AddUnit()
		c.Assert(err, jc.ErrorIsNil)
		msru, err := rel.Unit(msu)
		c.Assert(err, jc.ErrorIsNil)
		c.Assert(msru.Endpoint(), gc.Equals, mysqlEP)
		err = msru.EnterScope(nil)
		c.Assert(err, jc.ErrorIsNil)
		err = msru.LeaveScope()
		c.Assert(err, jc.ErrorIsNil)
		lgu, err := s.State.Unit("logging/" + strconv.Itoa(i))
		c.Assert(err, jc.ErrorIsNil)
		lgru, err := rel.Unit(lgu)
		c.Assert(err, jc.ErrorIsNil)
		c.Assert(lgru.Endpoint(), gc.Equals, loggingEP)
		return msru, lgru
	}
	msru0, lgru0 := addUnits(0)
	msru1, lgru1 := addUnits(1)

	// ---------- Single role active ----------

	// Start watching the relation from the perspective of the first unit, and
	// check the initial event.
	msw0 := msru0.Watch()
	defer testing.AssertStop(c, msw0)
	msw0c := testing.NewRelationUnitsWatcherC(c, s.State, msw0)
	msw0c.AssertChange(nil, nil)
	msw0c.AssertNoChange()

	// Join the unit to the relation, change its settings, and check that
	// nothing apparently happens.
	err = msru0.EnterScope(nil)
	c.Assert(err, jc.ErrorIsNil)
	changeSettings(c, msru0)
	msw0c.AssertNoChange()

	// Watch the relation from the perspective of the second provider, and
	// check initial event.
	msw1 := msru1.Watch()
	defer testing.AssertStop(c, msw1)
	msw1c := testing.NewRelationUnitsWatcherC(c, s.State, msw1)
	msw1c.AssertChange(nil, nil)
	msw1c.AssertNoChange()

	// Join the second provider unit to the relation, and check that neither
	// watching unit observes any change.
	err = msru1.EnterScope(nil)
	c.Assert(err, jc.ErrorIsNil)
	msw1c.AssertNoChange()
	msw0c.AssertNoChange()

	// Change the unit's settings, and check that nothing apparently happens.
	changeSettings(c, msru1)
	msw1c.AssertNoChange()
	msw0c.AssertNoChange()

	// ---------- Two roles active ----------

	// Start a watch from the first requirer unit's perspective, and check it
	// only sees the first provider (with which it shares a container).
	lgw0 := lgru0.Watch()
	defer testing.AssertStop(c, lgw0)
	lgw0c := testing.NewRelationUnitsWatcherC(c, s.State, lgw0)
	expectChanged := []string{"mysql/0"}
	lgw0c.AssertChange(expectChanged, nil)
	lgw0c.AssertNoChange()

	// Join the first requirer unit, and check that only the first provider
	// observes the change.
	err = lgru0.EnterScope(nil)
	c.Assert(err, jc.ErrorIsNil)
	expectChanged = []string{"logging/0"}
	msw0c.AssertChange(expectChanged, nil)
	msw0c.AssertNoChange()
	msw1c.AssertNoChange()
	lgw0c.AssertNoChange()

	// Watch from the second requirer's perspective, and check it only sees the
	// second provider.
	lgw1 := lgru1.Watch()
	defer testing.AssertStop(c, lgw1)
	lgw1c := testing.NewRelationUnitsWatcherC(c, s.State, lgw1)
	expectChanged = []string{"mysql/1"}
	lgw1c.AssertChange(expectChanged, nil)
//.........这里部分代码省略.........

func (s *uniterSuite) TestWatchRelationUnits(c *gc.C) {
	// Add a relation between wordpress and mysql and enter scope with
	// mysqlUnit.
	rel := s.addRelation(c, "wordpress", "mysql")
	myRelUnit, err := rel.Unit(s.mysqlUnit)
	c.Assert(err, gc.IsNil)
	err = myRelUnit.EnterScope(nil)
	c.Assert(err, gc.IsNil)
	s.assertInScope(c, myRelUnit, true)

	c.Assert(s.resources.Count(), gc.Equals, 0)

	args := params.RelationUnits{RelationUnits: []params.RelationUnit{
		{Relation: "relation-42", Unit: "unit-foo-0"},
		{Relation: rel.Tag(), Unit: "unit-wordpress-0"},
		{Relation: rel.Tag(), Unit: "unit-mysql-0"},
		{Relation: "relation-42", Unit: "unit-wordpress-0"},
		{Relation: "relation-foo", Unit: ""},
		{Relation: "service-wordpress", Unit: "unit-foo-0"},
		{Relation: "foo", Unit: "bar"},
		{Relation: rel.Tag(), Unit: "unit-mysql-0"},
		{Relation: rel.Tag(), Unit: "service-wordpress"},
		{Relation: rel.Tag(), Unit: "service-mysql"},
		{Relation: rel.Tag(), Unit: "user-admin"},
	}}
	result, err := s.uniter.WatchRelationUnits(args)
	c.Assert(err, gc.IsNil)
	// UnitSettings versions are volatile, so we don't check them.
	// We just make sure the keys of the Changed field are as
	// expected.
	c.Assert(result.Results, gc.HasLen, len(args.RelationUnits))
	mysqlChanges := result.Results[1].Changes
	c.Assert(mysqlChanges, gc.NotNil)
	changed, ok := mysqlChanges.Changed["mysql/0"]
	c.Assert(ok, jc.IsTrue)
	expectChanges := params.RelationUnitsChange{
		Changed: map[string]params.UnitSettings{"mysql/0": changed},
	}
	c.Assert(result, gc.DeepEquals, params.RelationUnitsWatchResults{
		Results: []params.RelationUnitsWatchResult{
			{Error: apiservertesting.ErrUnauthorized},
			{
				RelationUnitsWatcherId: "1",
				Changes:                expectChanges,
			},
			{Error: apiservertesting.ErrUnauthorized},
			{Error: apiservertesting.ErrUnauthorized},
			{Error: apiservertesting.ErrUnauthorized},
			{Error: apiservertesting.ErrUnauthorized},
			{Error: apiservertesting.ErrUnauthorized},
			{Error: apiservertesting.ErrUnauthorized},
			{Error: apiservertesting.ErrUnauthorized},
			{Error: apiservertesting.ErrUnauthorized},
			{Error: apiservertesting.ErrUnauthorized},
		},
	})

	// Verify the resource was registered and stop when done
	c.Assert(s.resources.Count(), gc.Equals, 1)
	resource := s.resources.Get("1")
	defer statetesting.AssertStop(c, resource)

	// Check that the Watch has consumed the initial event ("returned" in
	// the Watch call)
	wc := statetesting.NewRelationUnitsWatcherC(c, s.State, resource.(state.RelationUnitsWatcher))
	wc.AssertNoChange()

	// Leave scope with mysqlUnit and check it's detected.
	err = myRelUnit.LeaveScope()
	c.Assert(err, gc.IsNil)
	s.assertInScope(c, myRelUnit, false)

	wc.AssertChange(nil, []string{"mysql/0"})
}