func (s *SubnetsSuite) TestAllZonesWithNoBackingZonesAndSetFails(c *gc.C) {
	apiservertesting.BackingInstance.SetUp(c, apiservertesting.StubZonedEnvironName, apiservertesting.WithoutZones, apiservertesting.WithSpaces, apiservertesting.WithSubnets)
	apiservertesting.SharedStub.SetErrors(
		nil, // Backing.AvailabilityZones
		nil, // Backing.EnvironConfig
		nil, // Provider.Open
		nil, // ZonedEnviron.AvailabilityZones
		errors.NotSupportedf("setting"), // Backing.SetAvailabilityZones
	)

	results, err := s.facade.AllZones()
	c.Assert(err, gc.ErrorMatches,
		`cannot update known zones: setting not supported`,
	)
	// Verify the cause is not obscured.
	c.Assert(err, jc.Satisfies, errors.IsNotSupported)
	c.Assert(results, jc.DeepEquals, params.ZoneResults{})

	apiservertesting.CheckMethodCalls(c, apiservertesting.SharedStub,
		apiservertesting.BackingCall("AvailabilityZones"),
		apiservertesting.BackingCall("EnvironConfig"),
		apiservertesting.ProviderCall("Open", apiservertesting.BackingInstance.EnvConfig),
		apiservertesting.ZonedEnvironCall("AvailabilityZones"),
		apiservertesting.BackingCall("SetAvailabilityZones", apiservertesting.ProviderInstance.Zones),
	)
}

func (s *SubnetsSuite) TestAllZonesWithNoBackingZonesAndFetchingZonesFails(c *gc.C) {
	apiservertesting.BackingInstance.SetUp(
		c,
		apiservertesting.StubZonedEnvironName,
		apiservertesting.WithoutZones,
		apiservertesting.WithSpaces,
		apiservertesting.WithSubnets)

	apiservertesting.SharedStub.SetErrors(
		nil, // Backing.AvailabilityZones
		nil, // Backing.ModelConfig
		nil, // Backing.CloudSpec
		nil, // Provider.Open
		errors.NotValidf("foo"), // ZonedEnviron.AvailabilityZones
	)

	results, err := networkingcommon.AllZones(apiservertesting.BackingInstance)
	c.Assert(err, gc.ErrorMatches,
		`cannot update known zones: foo not valid`,
	)
	// Verify the cause is not obscured.
	c.Assert(err, jc.Satisfies, errors.IsNotValid)
	c.Assert(results, jc.DeepEquals, params.ZoneResults{})

	apiservertesting.CheckMethodCalls(c, apiservertesting.SharedStub,
		apiservertesting.BackingCall("AvailabilityZones"),
		apiservertesting.BackingCall("ModelConfig"),
		apiservertesting.BackingCall("CloudSpec"),
		apiservertesting.ProviderCall("Open", apiservertesting.BackingInstance.EnvConfig),
		apiservertesting.ZonedEnvironCall("AvailabilityZones"),
	)
}

func (s *SubnetsSuite) TestAllZonesWithNoBackingZonesUpdates(c *gc.C) {
	apiservertesting.BackingInstance.SetUp(c, apiservertesting.StubZonedEnvironName, apiservertesting.WithoutZones, apiservertesting.WithSpaces, apiservertesting.WithSubnets)

	results, err := s.facade.AllZones()
	c.Assert(err, jc.ErrorIsNil)
	s.AssertAllZonesResult(c, results, apiservertesting.ProviderInstance.Zones)

	apiservertesting.CheckMethodCalls(c, apiservertesting.SharedStub,
		apiservertesting.BackingCall("AvailabilityZones"),
		apiservertesting.BackingCall("EnvironConfig"),
		apiservertesting.ProviderCall("Open", apiservertesting.BackingInstance.EnvConfig),
		apiservertesting.ZonedEnvironCall("AvailabilityZones"),
		apiservertesting.BackingCall("SetAvailabilityZones", apiservertesting.ProviderInstance.Zones),
	)
}

func (s *SubnetsSuite) CheckAddSubnetsFails(
	c *gc.C, envName string,
	withZones, withSpaces, withSubnets apiservertesting.SetUpFlag,
	expectedError string,
) {

	apiservertesting.BackingInstance.SetUp(c, envName, withZones, withSpaces, withSubnets)

	// These calls always happen.
	expectedCalls := []apiservertesting.StubMethodCall{
		apiservertesting.BackingCall("EnvironConfig"),
		apiservertesting.ProviderCall("Open", apiservertesting.BackingInstance.EnvConfig),
	}

	// Subnets is also always called. but the receiver is different.
	switch envName {
	case apiservertesting.StubNetworkingEnvironName:
		expectedCalls = append(
			expectedCalls,
			apiservertesting.NetworkingEnvironCall("Subnets", instance.UnknownId, []network.Id(nil)),
		)
	case apiservertesting.StubZonedNetworkingEnvironName:
		expectedCalls = append(
			expectedCalls,
			apiservertesting.ZonedNetworkingEnvironCall("Subnets", instance.UnknownId, []network.Id(nil)),
		)
	}

	if !withSubnets {
		// Set provider subnets to empty for this test.
		originalSubnets := make([]network.SubnetInfo, len(apiservertesting.ProviderInstance.Subnets))
		copy(originalSubnets, apiservertesting.ProviderInstance.Subnets)
		apiservertesting.ProviderInstance.Subnets = []network.SubnetInfo{}

		defer func() {
			apiservertesting.ProviderInstance.Subnets = make([]network.SubnetInfo, len(originalSubnets))
			copy(apiservertesting.ProviderInstance.Subnets, originalSubnets)
		}()

		if envName == apiservertesting.StubEnvironName || envName == apiservertesting.StubNetworkingEnvironName {
			// networking is either not supported or no subnets are
			// defined, so expected the same calls for each of the two
			// arguments to AddSubnets() below.
			expectedCalls = append(expectedCalls, expectedCalls...)
		}
	} else {
		// Having subnets implies spaces will be cached as well.
		expectedCalls = append(expectedCalls, apiservertesting.BackingCall("AllSpaces"))
	}

	if withSpaces && withSubnets {
		// Having both subnets and spaces means we'll also cache zones.
		expectedCalls = append(expectedCalls, apiservertesting.BackingCall("AvailabilityZones"))
	}

	if !withZones && withSpaces {
		// Set provider zones to empty for this test.
		originalZones := make([]providercommon.AvailabilityZone, len(apiservertesting.ProviderInstance.Zones))
		copy(originalZones, apiservertesting.ProviderInstance.Zones)
		apiservertesting.ProviderInstance.Zones = []providercommon.AvailabilityZone{}

		defer func() {
			apiservertesting.ProviderInstance.Zones = make([]providercommon.AvailabilityZone, len(originalZones))
			copy(apiservertesting.ProviderInstance.Zones, originalZones)
		}()

		// updateZones tries to constructs a ZonedEnviron with these calls.
		zoneCalls := append([]apiservertesting.StubMethodCall{},
			apiservertesting.BackingCall("EnvironConfig"),
			apiservertesting.ProviderCall("Open", apiservertesting.BackingInstance.EnvConfig),
		)
		// Receiver can differ according to envName, but
		// AvailabilityZones() will be called on either receiver.
		switch envName {
		case apiservertesting.StubZonedEnvironName:
			zoneCalls = append(
				zoneCalls,
				apiservertesting.ZonedEnvironCall("AvailabilityZones"),
			)
		case apiservertesting.StubZonedNetworkingEnvironName:
			zoneCalls = append(
				zoneCalls,
				apiservertesting.ZonedNetworkingEnvironCall("AvailabilityZones"),
			)
		}
		// Finally after caching provider zones backing zones are
		// updated.
		zoneCalls = append(
			zoneCalls,
			apiservertesting.BackingCall("SetAvailabilityZones", apiservertesting.ProviderInstance.Zones),
		)

		// Now, because we have 2 arguments to AddSubnets() below, we
		// need to expect the same zoneCalls twice, with a
		// AvailabilityZones backing lookup between them.
		expectedCalls = append(expectedCalls, zoneCalls...)
		expectedCalls = append(expectedCalls, apiservertesting.BackingCall("AvailabilityZones"))
		expectedCalls = append(expectedCalls, zoneCalls...)
	}

//.........这里部分代码省略.........