Ejemplo n.º 1
0
func (s *machineSuite) TestWatchUnits(c *gc.C) {
	w, err := s.apiMachine.WatchUnits()
	c.Assert(err, gc.IsNil)
	defer statetesting.AssertStop(c, w)
	wc := statetesting.NewStringsWatcherC(c, s.BackingState, w)

	// Initial event.
	wc.AssertChange("wordpress/0")
	wc.AssertNoChange()

	// Change something other than the life cycle and make sure it's
	// not detected.
	err = s.machines[0].SetPassword("foo")
	c.Assert(err, gc.ErrorMatches, "password is only 3 bytes long, and is not a valid Agent password")
	wc.AssertNoChange()

	err = s.machines[0].SetPassword("foo-12345678901234567890")
	c.Assert(err, gc.IsNil)
	wc.AssertNoChange()

	// Unassign unit 0 from the machine and check it's detected.
	err = s.units[0].UnassignFromMachine()
	c.Assert(err, gc.IsNil)
	wc.AssertChange("wordpress/0")
	wc.AssertNoChange()

	statetesting.AssertStop(c, w)
	wc.AssertClosed()
}
Ejemplo n.º 2
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func (s *deployerSuite) TestWatchUnits(c *gc.C) {
	machine, err := s.st.Machine(s.machine.Tag())
	c.Assert(err, gc.IsNil)
	w, err := machine.WatchUnits()
	c.Assert(err, gc.IsNil)
	defer statetesting.AssertStop(c, w)
	wc := statetesting.NewStringsWatcherC(c, s.BackingState, w)

	// Initial event.
	wc.AssertChange("mysql/0", "logging/0")
	wc.AssertNoChange()

	// Change something other than the lifecycle and make sure it's
	// not detected.
	err = s.subordinate.SetPassword("foo")
	c.Assert(err, gc.ErrorMatches, "password is only 3 bytes long, and is not a valid Agent password")
	wc.AssertNoChange()

	err = s.subordinate.SetPassword("foo-12345678901234567890")
	c.Assert(err, gc.IsNil)
	wc.AssertNoChange()

	// Make the subordinate dead and check it's detected.
	err = s.subordinate.EnsureDead()
	c.Assert(err, gc.IsNil)
	wc.AssertChange("logging/0")
	wc.AssertNoChange()

	statetesting.AssertStop(c, w)
	wc.AssertClosed()
}
Ejemplo n.º 3
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func (s *watcherSuite) TestStringsWatcherStopsWithPendingSend(c *gc.C) {
	// Call the Deployer facade's WatchUnits for machine-0.
	var results params.StringsWatchResults
	args := params.Entities{Entities: []params.Entity{{Tag: s.rawMachine.Tag()}}}
	err := s.stateAPI.Call("Deployer", "", "WatchUnits", args, &results)
	c.Assert(err, gc.IsNil)
	c.Assert(results.Results, gc.HasLen, 1)
	result := results.Results[0]
	c.Assert(result.Error, gc.IsNil)

	// Start a StringsWatcher and check the initial event.
	w := watcher.NewStringsWatcher(s.stateAPI, result)
	wc := statetesting.NewStringsWatcherC(c, s.State, w)

	// Create a service, deploy a unit of it on the machine.
	mysql := s.AddTestingService(c, "mysql", s.AddTestingCharm(c, "mysql"))
	principal, err := mysql.AddUnit()
	c.Assert(err, gc.IsNil)
	err = principal.AssignToMachine(s.rawMachine)
	c.Assert(err, gc.IsNil)

	// Ensure the initial event is delivered. Then test the watcher
	// can be stopped cleanly without reading the pending change.
	s.BackingState.StartSync()
	statetesting.AssertCanStopWhenSending(c, w)
	wc.AssertClosed()
}
Ejemplo n.º 4
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func (s *withoutStateServerSuite) TestWatchEnvironMachines(c *gc.C) {
	c.Assert(s.resources.Count(), gc.Equals, 0)

	got, err := s.provisioner.WatchEnvironMachines()
	c.Assert(err, gc.IsNil)
	want := params.StringsWatchResult{
		StringsWatcherId: "1",
		Changes:          []string{"0", "1", "2", "3", "4"},
	}
	c.Assert(got.StringsWatcherId, gc.Equals, want.StringsWatcherId)
	c.Assert(got.Changes, jc.SameContents, want.Changes)

	// Verify the resources were registered and stop them 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.NewStringsWatcherC(c, s.State, resource.(state.StringsWatcher))
	wc.AssertNoChange()

	// Make sure WatchEnvironMachines fails with a machine agent login.
	anAuthorizer := s.authorizer
	anAuthorizer.MachineAgent = true
	anAuthorizer.EnvironManager = false
	aProvisioner, err := provisioner.NewProvisionerAPI(s.State, s.resources, anAuthorizer)
	c.Assert(err, gc.IsNil)

	result, err := aProvisioner.WatchEnvironMachines()
	c.Assert(err, gc.ErrorMatches, "permission denied")
	c.Assert(result, gc.DeepEquals, params.StringsWatchResult{})
}
Ejemplo n.º 5
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func (s *firewallerSuite) TestWatchUnits(c *gc.C) {
	c.Assert(s.resources.Count(), gc.Equals, 0)

	args := addFakeEntities(params.Entities{Entities: []params.Entity{
		{Tag: s.machines[0].Tag()},
		{Tag: s.service.Tag()},
		{Tag: s.units[0].Tag()},
	}})
	result, err := s.firewaller.WatchUnits(args)
	c.Assert(err, gc.IsNil)
	c.Assert(result, jc.DeepEquals, params.StringsWatchResults{
		Results: []params.StringsWatchResult{
			{Changes: []string{"wordpress/0"}, StringsWatcherId: "1"},
			{Error: apiservertesting.ErrUnauthorized},
			{Error: apiservertesting.ErrUnauthorized},
			{Error: apiservertesting.NotFoundError("machine 42")},
			{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)
	c.Assert(result.Results[0].StringsWatcherId, 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.NewStringsWatcherC(c, s.State, resource.(state.StringsWatcher))
	wc.AssertNoChange()
}
Ejemplo n.º 6
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func (s *deployerSuite) TestWatchUnits(c *gc.C) {
	c.Assert(s.resources.Count(), gc.Equals, 0)

	args := params.Entities{Entities: []params.Entity{
		{Tag: "machine-1"},
		{Tag: "machine-0"},
		{Tag: "machine-42"},
	}}
	result, err := s.deployer.WatchUnits(args)
	c.Assert(err, gc.IsNil)
	sort.Strings(result.Results[0].Changes)
	c.Assert(result, gc.DeepEquals, params.StringsWatchResults{
		Results: []params.StringsWatchResult{
			{Changes: []string{"logging/0", "mysql/0"}, StringsWatcherId: "1"},
			{Error: apiservertesting.ErrUnauthorized},
			{Error: apiservertesting.ErrUnauthorized},
		},
	})

	// Verify the resource was registered and stop when done
	c.Assert(s.resources.Count(), gc.Equals, 1)
	c.Assert(result.Results[0].StringsWatcherId, 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.NewStringsWatcherC(c, s.State, resource.(state.StringsWatcher))
	wc.AssertNoChange()
}
Ejemplo n.º 7
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func (s *serviceSuite) TestWatchRelations(c *gc.C) {
	w, err := s.apiService.WatchRelations()
	c.Assert(err, gc.IsNil)
	defer statetesting.AssertStop(c, w)
	wc := statetesting.NewStringsWatcherC(c, s.BackingState, w)

	// Initial event.
	wc.AssertChange()
	wc.AssertNoChange()

	// Change something other than the lifecycle and make sure it's
	// not detected.
	err = s.wordpressService.SetExposed()
	c.Assert(err, gc.IsNil)
	wc.AssertNoChange()

	// Add another service and relate it to wordpress,
	// check it's detected.
	s.addMachineServiceCharmAndUnit(c, "mysql")
	rel := s.addRelation(c, "wordpress", "mysql")
	wc.AssertChange(rel.String())

	// Destroy the relation and check it's detected.
	err = rel.Destroy()
	c.Assert(err, gc.IsNil)
	wc.AssertChange(rel.String())
	wc.AssertNoChange()

	statetesting.AssertStop(c, w)
	wc.AssertClosed()
}
Ejemplo n.º 8
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func (s *provisionerSuite) TestWatchEnvironMachines(c *gc.C) {
	w, err := s.provisioner.WatchEnvironMachines()
	c.Assert(err, gc.IsNil)
	defer statetesting.AssertStop(c, w)
	wc := statetesting.NewStringsWatcherC(c, s.BackingState, w)

	// Initial event.
	wc.AssertChange(s.machine.Id())

	// Add another 2 machines make sure they are detected.
	otherMachine, err := s.State.AddMachine("quantal", state.JobHostUnits)
	c.Assert(err, gc.IsNil)
	otherMachine, err = s.State.AddMachine("quantal", state.JobHostUnits)
	c.Assert(err, gc.IsNil)
	wc.AssertChange("1", "2")

	// Change the lifecycle of last machine.
	err = otherMachine.EnsureDead()
	c.Assert(err, gc.IsNil)
	wc.AssertChange("2")

	// Add a container and make sure it's not detected.
	template := state.MachineTemplate{
		Series: "quantal",
		Jobs:   []state.MachineJob{state.JobHostUnits},
	}
	_, err = s.State.AddMachineInsideMachine(template, s.machine.Id(), instance.LXC)
	c.Assert(err, gc.IsNil)
	wc.AssertNoChange()

	statetesting.AssertStop(c, w)
	wc.AssertClosed()
}
Ejemplo n.º 9
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func (s *watcherSuite) TestWatchUnitsKeepsEvents(c *gc.C) {
	// Create two services, relate them, and add one unit to each - a
	// principal and a subordinate.
	mysql := s.AddTestingService(c, "mysql", s.AddTestingCharm(c, "mysql"))
	logging := s.AddTestingService(c, "logging", s.AddTestingCharm(c, "logging"))
	eps, err := s.State.InferEndpoints([]string{"mysql", "logging"})
	c.Assert(err, gc.IsNil)
	rel, err := s.State.AddRelation(eps...)
	c.Assert(err, gc.IsNil)
	principal, err := mysql.AddUnit()
	c.Assert(err, gc.IsNil)
	err = principal.AssignToMachine(s.rawMachine)
	c.Assert(err, gc.IsNil)
	relUnit, err := rel.Unit(principal)
	c.Assert(err, gc.IsNil)
	err = relUnit.EnterScope(nil)
	c.Assert(err, gc.IsNil)
	subordinate, err := logging.Unit("logging/0")
	c.Assert(err, gc.IsNil)

	// Call the Deployer facade's WatchUnits for machine-0.
	var results params.StringsWatchResults
	args := params.Entities{Entities: []params.Entity{{Tag: s.rawMachine.Tag()}}}
	err = s.stateAPI.Call("Deployer", "", "WatchUnits", args, &results)
	c.Assert(err, gc.IsNil)
	c.Assert(results.Results, gc.HasLen, 1)
	result := results.Results[0]
	c.Assert(result.Error, gc.IsNil)

	// Start a StringsWatcher and check the initial event.
	w := watcher.NewStringsWatcher(s.stateAPI, result)
	wc := statetesting.NewStringsWatcherC(c, s.State, w)
	wc.AssertChange("mysql/0", "logging/0")
	wc.AssertNoChange()

	// Now, without reading any changes advance the lifecycle of both
	// units, inducing an update server-side after each two changes to
	// ensure they're reported as separate events over the API.
	err = subordinate.EnsureDead()
	c.Assert(err, gc.IsNil)
	s.BackingState.StartSync()
	err = subordinate.Remove()
	c.Assert(err, gc.IsNil)
	err = principal.EnsureDead()
	c.Assert(err, gc.IsNil)
	s.BackingState.StartSync()

	// Expect these changes as 2 separate events, so that
	// nothing gets lost.
	wc.AssertChange("logging/0")
	wc.AssertChange("mysql/0")
	wc.AssertNoChange()

	statetesting.AssertStop(c, w)
	wc.AssertClosed()
}
Ejemplo n.º 10
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func (s *withoutStateServerSuite) TestWatchAllContainers(c *gc.C) {
	c.Assert(s.resources.Count(), gc.Equals, 0)

	args := params.WatchContainers{Params: []params.WatchContainer{
		{MachineTag: s.machines[0].Tag()},
		{MachineTag: s.machines[1].Tag()},
		{MachineTag: "machine-42"},
		{MachineTag: "unit-foo-0"},
		{MachineTag: "service-bar"},
	}}
	result, err := s.provisioner.WatchAllContainers(args)
	c.Assert(err, gc.IsNil)
	c.Assert(result, gc.DeepEquals, params.StringsWatchResults{
		Results: []params.StringsWatchResult{
			{StringsWatcherId: "1", Changes: []string{}},
			{StringsWatcherId: "2", Changes: []string{}},
			{Error: apiservertesting.NotFoundError("machine 42")},
			{Error: apiservertesting.ErrUnauthorized},
			{Error: apiservertesting.ErrUnauthorized},
		},
	})

	// Verify the resources were registered and stop them when done.
	c.Assert(s.resources.Count(), gc.Equals, 2)
	m0Watcher := s.resources.Get("1")
	defer statetesting.AssertStop(c, m0Watcher)
	m1Watcher := s.resources.Get("2")
	defer statetesting.AssertStop(c, m1Watcher)

	// Check that the Watch has consumed the initial event ("returned"
	// in the Watch call)
	wc0 := statetesting.NewStringsWatcherC(c, s.State, m0Watcher.(state.StringsWatcher))
	wc0.AssertNoChange()
	wc1 := statetesting.NewStringsWatcherC(c, s.State, m1Watcher.(state.StringsWatcher))
	wc1.AssertNoChange()
}
Ejemplo n.º 11
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func (s *ServiceSuite) TestWatchUnitsLifecycle(c *gc.C) {
	// Empty initial event when no units.
	w := s.mysql.WatchUnits()
	defer testing.AssertStop(c, w)
	wc := testing.NewStringsWatcherC(c, s.State, w)
	wc.AssertChange()
	wc.AssertNoChange()

	// Create one unit, check one change.
	quick, err := s.mysql.AddUnit()
	c.Assert(err, gc.IsNil)
	wc.AssertChange(quick.Name())
	wc.AssertNoChange()

	// Destroy that unit (short-circuited to removal), check one change.
	err = quick.Destroy()
	c.Assert(err, gc.IsNil)
	wc.AssertChange(quick.Name())
	wc.AssertNoChange()

	// Create another, check one change.
	slow, err := s.mysql.AddUnit()
	c.Assert(err, gc.IsNil)
	wc.AssertChange(slow.Name())
	wc.AssertNoChange()

	// Change unit itself, no change.
	preventUnitDestroyRemove(c, slow)
	wc.AssertNoChange()

	// Make unit Dying, change detected.
	err = slow.Destroy()
	c.Assert(err, gc.IsNil)
	wc.AssertChange(slow.Name())
	wc.AssertNoChange()

	// Make unit Dead, change detected.
	err = slow.EnsureDead()
	c.Assert(err, gc.IsNil)
	wc.AssertChange(slow.Name())
	wc.AssertNoChange()

	// Remove unit, final change not detected.
	err = slow.Remove()
	c.Assert(err, gc.IsNil)
	wc.AssertNoChange()
}
Ejemplo n.º 12
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func (s *ServiceSuite) TestWatchUnitsBulkEvents(c *gc.C) {
	// Alive unit...
	alive, err := s.mysql.AddUnit()
	c.Assert(err, gc.IsNil)

	// Dying unit...
	dying, err := s.mysql.AddUnit()
	c.Assert(err, gc.IsNil)
	preventUnitDestroyRemove(c, dying)
	err = dying.Destroy()
	c.Assert(err, gc.IsNil)

	// Dead unit...
	dead, err := s.mysql.AddUnit()
	c.Assert(err, gc.IsNil)
	preventUnitDestroyRemove(c, dead)
	err = dead.Destroy()
	c.Assert(err, gc.IsNil)
	err = dead.EnsureDead()
	c.Assert(err, gc.IsNil)

	// Gone unit.
	gone, err := s.mysql.AddUnit()
	c.Assert(err, gc.IsNil)
	err = gone.Destroy()
	c.Assert(err, gc.IsNil)

	// All except gone unit are reported in initial event.
	w := s.mysql.WatchUnits()
	defer testing.AssertStop(c, w)
	wc := testing.NewStringsWatcherC(c, s.State, w)
	wc.AssertChange(alive.Name(), dying.Name(), dead.Name())
	wc.AssertNoChange()

	// Remove them all; alive/dying changes reported; dead never mentioned again.
	err = alive.Destroy()
	c.Assert(err, gc.IsNil)
	err = dying.EnsureDead()
	c.Assert(err, gc.IsNil)
	err = dying.Remove()
	c.Assert(err, gc.IsNil)
	err = dead.Remove()
	c.Assert(err, gc.IsNil)
	wc.AssertChange(alive.Name(), dying.Name())
	wc.AssertNoChange()
}
Ejemplo n.º 13
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func (s *uniterSuite) assertOneStringsWatcher(c *gc.C, result params.StringsWatchResults, err error) {
	c.Assert(err, gc.IsNil)
	c.Assert(result.Results, gc.HasLen, 3)
	c.Assert(result.Results[0].Error, gc.DeepEquals, apiservertesting.ErrUnauthorized)
	c.Assert(result.Results[1].StringsWatcherId, gc.Equals, "1")
	c.Assert(result.Results[1].Changes, gc.NotNil)
	c.Assert(result.Results[1].Error, gc.IsNil)
	c.Assert(result.Results[2].Error, gc.DeepEquals, 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.NewStringsWatcherC(c, s.State, resource.(state.StringsWatcher))
	wc.AssertNoChange()
}
Ejemplo n.º 14
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func (s *firewallerSuite) TestWatchEnvironMachines(c *gc.C) {
	c.Assert(s.resources.Count(), gc.Equals, 0)

	got, err := s.firewaller.WatchEnvironMachines()
	c.Assert(err, gc.IsNil)
	want := params.StringsWatchResult{
		StringsWatcherId: "1",
		Changes:          []string{"0", "1", "2"},
	}
	c.Assert(got.StringsWatcherId, gc.Equals, want.StringsWatcherId)
	c.Assert(got.Changes, jc.SameContents, want.Changes)

	// Verify the resources were registered and stop them 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.NewStringsWatcherC(c, s.State, resource.(state.StringsWatcher))
	wc.AssertNoChange()
}
Ejemplo n.º 15
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func (s *provisionerSuite) TestWatchContainers(c *gc.C) {
	apiMachine, err := s.provisioner.Machine(s.machine.Tag())
	c.Assert(err, gc.IsNil)

	// Add one LXC container.
	template := state.MachineTemplate{
		Series: "quantal",
		Jobs:   []state.MachineJob{state.JobHostUnits},
	}
	container, err := s.State.AddMachineInsideMachine(template, s.machine.Id(), instance.LXC)
	c.Assert(err, gc.IsNil)

	w, err := apiMachine.WatchContainers(instance.LXC)
	c.Assert(err, gc.IsNil)
	defer statetesting.AssertStop(c, w)
	wc := statetesting.NewStringsWatcherC(c, s.BackingState, w)

	// Initial event.
	wc.AssertChange(container.Id())

	// Change something other than the containers and make sure it's
	// not detected.
	err = apiMachine.SetStatus(params.StatusStarted, "not really", nil)
	c.Assert(err, gc.IsNil)
	wc.AssertNoChange()

	// Add a KVM container and make sure it's not detected.
	container, err = s.State.AddMachineInsideMachine(template, s.machine.Id(), instance.KVM)
	c.Assert(err, gc.IsNil)
	wc.AssertNoChange()

	// Add another LXC container and make sure it's detected.
	container, err = s.State.AddMachineInsideMachine(template, s.machine.Id(), instance.LXC)
	c.Assert(err, gc.IsNil)
	wc.AssertChange(container.Id())

	statetesting.AssertStop(c, w)
	wc.AssertClosed()
}
Ejemplo n.º 16
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func (s *ServiceSuite) TestWatchRelations(c *gc.C) {
	// TODO(fwereade) split this test up a bit.
	w := s.mysql.WatchRelations()
	defer testing.AssertStop(c, w)
	wc := testing.NewStringsWatcherC(c, s.State, w)
	wc.AssertChange()
	wc.AssertNoChange()

	// Add a relation; check change.
	mysqlep, err := s.mysql.Endpoint("server")
	c.Assert(err, gc.IsNil)
	wpch := s.AddTestingCharm(c, "wordpress")
	wpi := 0
	addRelation := func() *state.Relation {
		name := fmt.Sprintf("wp%d", wpi)
		wpi++
		wp := s.AddTestingService(c, name, wpch)
		wpep, err := wp.Endpoint("db")
		c.Assert(err, gc.IsNil)
		rel, err := s.State.AddRelation(mysqlep, wpep)
		c.Assert(err, gc.IsNil)
		return rel
	}
	rel0 := addRelation()
	wc.AssertChange(rel0.String())
	wc.AssertNoChange()

	// Add another relation; check change.
	rel1 := addRelation()
	wc.AssertChange(rel1.String())
	wc.AssertNoChange()

	// Destroy a relation; check change.
	err = rel0.Destroy()
	c.Assert(err, gc.IsNil)
	wc.AssertChange(rel0.String())
	wc.AssertNoChange()

	// Stop watcher; check change chan is closed.
	testing.AssertStop(c, w)
	wc.AssertClosed()

	// Add a new relation; start a new watcher; check initial event.
	rel2 := addRelation()
	w = s.mysql.WatchRelations()
	defer testing.AssertStop(c, w)
	wc = testing.NewStringsWatcherC(c, s.State, w)
	wc.AssertChange(rel1.String(), rel2.String())
	wc.AssertNoChange()

	// Add a unit to the new relation; check no change.
	unit, err := s.mysql.AddUnit()
	c.Assert(err, gc.IsNil)
	ru2, err := rel2.Unit(unit)
	c.Assert(err, gc.IsNil)
	err = ru2.EnterScope(nil)
	c.Assert(err, gc.IsNil)
	wc.AssertNoChange()

	// Destroy the relation with the unit in scope, and add another; check
	// changes.
	err = rel2.Destroy()
	c.Assert(err, gc.IsNil)
	rel3 := addRelation()
	wc.AssertChange(rel2.String(), rel3.String())
	wc.AssertNoChange()

	// Leave scope, destroying the relation, and check that change as well.
	err = ru2.LeaveScope()
	c.Assert(err, gc.IsNil)
	wc.AssertChange(rel2.String())
	wc.AssertNoChange()
}
Ejemplo n.º 17
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func (s *UnitSuite) TestWatchSubordinates(c *gc.C) {
	w := s.unit.WatchSubordinateUnits()
	defer testing.AssertStop(c, w)
	wc := testing.NewStringsWatcherC(c, s.State, w)
	wc.AssertChange()
	wc.AssertNoChange()

	// Add a couple of subordinates, check change.
	subCharm := s.AddTestingCharm(c, "logging")
	var subUnits []*state.Unit
	for i := 0; i < 2; i++ {
		// Note: subordinate units can only be created as a side effect of a
		// principal entering scope; and a given principal can only have a
		// single subordinate unit of each service.
		name := "logging" + strconv.Itoa(i)
		subSvc := s.AddTestingService(c, name, subCharm)
		eps, err := s.State.InferEndpoints([]string{name, "wordpress"})
		c.Assert(err, gc.IsNil)
		rel, err := s.State.AddRelation(eps...)
		c.Assert(err, gc.IsNil)
		ru, err := rel.Unit(s.unit)
		c.Assert(err, gc.IsNil)
		err = ru.EnterScope(nil)
		c.Assert(err, gc.IsNil)
		units, err := subSvc.AllUnits()
		c.Assert(err, gc.IsNil)
		c.Assert(units, gc.HasLen, 1)
		subUnits = append(subUnits, units[0])
	}
	wc.AssertChange(subUnits[0].Name(), subUnits[1].Name())
	wc.AssertNoChange()

	// Set one to Dying, check change.
	err := subUnits[0].Destroy()
	c.Assert(err, gc.IsNil)
	wc.AssertChange(subUnits[0].Name())
	wc.AssertNoChange()

	// Set both to Dead, and remove one; check change.
	err = subUnits[0].EnsureDead()
	c.Assert(err, gc.IsNil)
	err = subUnits[1].EnsureDead()
	c.Assert(err, gc.IsNil)
	err = subUnits[1].Remove()
	c.Assert(err, gc.IsNil)
	wc.AssertChange(subUnits[0].Name(), subUnits[1].Name())
	wc.AssertNoChange()

	// Stop watcher, check closed.
	testing.AssertStop(c, w)
	wc.AssertClosed()

	// Start a new watch, check Dead unit is reported.
	w = s.unit.WatchSubordinateUnits()
	defer testing.AssertStop(c, w)
	wc = testing.NewStringsWatcherC(c, s.State, w)
	wc.AssertChange(subUnits[0].Name())
	wc.AssertNoChange()

	// Remove the leftover, check no change.
	err = subUnits[0].Remove()
	c.Assert(err, gc.IsNil)
	wc.AssertNoChange()
}