SourceStatsReporter UT fix (#667)

* source stats reporter... should be used by well-behaved sources

* public fields

* moving serialization/deserialization of metrics and logging maps to pkg

* nits

* adding UT

* same order

* updates

* sock-puppet

* unregistration problem?

* removing base64 encoding

* removing TODO

* removing config changes... done in another PR

* to properly address the comment

* changing importer to source

* moving stats_reporter to new source folder

* fixing UT

source/source_stats_reporter_test.go

@@ -24,16 +24,8 @@ import (
 	"knative.dev/pkg/metrics/metricstest"
 )
 
-// unregister, ehm, unregisters the metrics that were registered, by
-// virtue of StatsReporter creation.
-// Since golang executes test iterations within the same process, the stats reporter
-// returns an error if the metric is already registered and the test panics.
-func unregister() {
-	metricstest.Unregister("event_count")
-}
-
 func TestStatsReporter(t *testing.T) {
-	t.Skip("Fails in PROW but not locally, possibly due to the webhook stats_reporter test. Needs further investigation.")
+	setup()
 
 	args := &ReportArgs{
 		Namespace:     "testns",
@@ -47,9 +39,6 @@ func TestStatsReporter(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to create a new reporter: %v", err)
 	}
-	// Without this `go test ... -count=X`, where X > 1, fails, since
-	// we get an error about view already being registered.
-	defer unregister()
 
 	wantTags := map[string]string{
 		metricskey.LabelNamespaceName:       "testns",
@@ -77,3 +66,13 @@ func expectSuccess(t *testing.T, f func() error) {
 		t.Errorf("Reporter expected success but got error: %v", err)
 	}
 }
+
+func setup() {
+	resetMetrics()
+}
+
+func resetMetrics() {
+	// OpenCensus metrics carry global state that need to be reset between unit tests.
+	metricstest.Unregister("event_count")
+	register()
+}