Merge pull request juju#17361 from hpidcock/typed-mock-returns

juju#17361

Gomock has a new-ish feature to implement typed Return/Do/DoAndReturn methods on the EXPECT types.

This enables it on all the mockgen calls and fixes up all the related issues from that.

## QA steps

Unit tests should pass.

## Documentation changes

N/A

## Links

**Jira card:** JUJU-

agent/addons/addons_test.go

@@ -147,8 +147,9 @@ func (s *registerSuite) TestRegisterEngineMetrics(c *gc.C) {
 
 	registry := NewMockRegisterer(ctrl)
 	registry.EXPECT().Register(collector)
-	registry.EXPECT().Unregister(collector).Do(func(_ prometheus.Collector) {
+	registry.EXPECT().Unregister(collector).Do(func(_ prometheus.Collector) bool {
 		close(done)
+		return false
 	})
 	sink := NewMockMetricSink(ctrl)
 	sink.EXPECT().Unregister()

agent/addons/package_test.go

@@ -9,8 +9,8 @@ import (
 	gc "gopkg.in/check.v1"
 )
 
-//go:generate go run go.uber.org/mock/mockgen -package addons_test -destination prometheus_mock_test.go github.com/prometheus/client_golang/prometheus Registerer
-//go:generate go run go.uber.org/mock/mockgen -package addons_test -destination engine_mock_test.go github.com/juju/juju/agent/engine MetricSink
+//go:generate go run go.uber.org/mock/mockgen -typed -package addons_test -destination prometheus_mock_test.go github.com/prometheus/client_golang/prometheus Registerer
+//go:generate go run go.uber.org/mock/mockgen -typed -package addons_test -destination engine_mock_test.go github.com/juju/juju/agent/engine MetricSink
 
 func Test(t *testing.T) {
 	gc.TestingT(t)