feat: make head pull failure warning toggleable (#912)

* feat: make head pull failure warning toggleable

* expect prometheus tests to go through EVENTUALLY

* wait for queue to be empty before checking test conditions

* clean up new head failure toggle

* fixup! clean up new head failure toggle

* test: add registry tests

* test: add warn on head failure tests

* fix client interface and make tests hit more lines

* make all tests use NewClient instead of creating a struct pointer

* fix lint issues

Co-authored-by: Simon Aronsson <simme@arcticbit.se>

pkg/metrics/metrics.go

@@ -24,6 +24,11 @@ type Metrics struct {
 	skipped prometheus.Counter
 }
 
+// QueueIsEmpty checks whether any messages are enqueued in the channel
+func (metrics *Metrics) QueueIsEmpty() bool {
+	return len(metrics.channel) == 0
+}
+
 // Register registers metrics for an executed scan
 func (metrics *Metrics) Register(metric *Metric) {
 	metrics.channel <- metric