Cover the loss window, rate window, error taxonomy and formatters with tests

main_test.go

@@ -1,6 +1,68 @@
 package main
 
-import "testing"
+import (
+	"testing"
+	"time"
+)
+
+func TestRateWindowLatestNeedsTwoBuckets(t *testing.T) {
+	w := newRateWindow(4)
+	if got := w.latest(rxRatePPS); got != 0 {
+		t.Errorf("empty ring gave %v, want 0", got)
+	}
+	w.push(counterSet{t: time.Now(), s: sample{rxFrames: 100}})
+	if got := w.latest(rxRatePPS); got != 0 {
+		t.Errorf("one bucket gave %v, want 0", got)
+	}
+}
+
+// The newest pair alone, so a step in the rate shows at once instead of being
+// averaged against everything still in the ring.
+func TestRateWindowLatestUsesNewestPair(t *testing.T) {
+	w := newRateWindow(4)
+	t0 := time.Now()
+	w.push(counterSet{t: t0, s: sample{rxFrames: 100}})
+	w.push(counterSet{t: t0.Add(time.Second), s: sample{rxFrames: 300}})
+	if got := w.latest(rxRatePPS); got != 200 {
+		t.Errorf("rate = %v, want 200", got)
+	}
+	w.push(counterSet{t: t0.Add(2 * time.Second), s: sample{rxFrames: 400}})
+	if got := w.latest(rxRatePPS); got != 100 {
+		t.Errorf("rate = %v, want 100 rather than the mean of the ring", got)
+	}
+}
+
+func TestRateWindowLatestIgnoresZeroSpan(t *testing.T) {
+	w := newRateWindow(4)
+	t0 := time.Now()
+	w.push(counterSet{t: t0, s: sample{rxFrames: 100}})
+	w.push(counterSet{t: t0, s: sample{rxFrames: 300}})
+	if got := w.latest(rxRatePPS); got != 0 {
+		t.Errorf("rate = %v, want 0", got)
+	}
+}
+
+// Which counter feeds which bucket is the whole taxonomy the panel reports, so
+// it is pinned here rather than left to whoever reads errsBetween next.
+func TestErrsBetweenBuckets(t *testing.T) {
+	n := counterSet{
+		s: sample{
+			lost: 1, late: 7,
+			crcErr: 2, badMagic: 3, badLen: 4,
+			txErrs: 6, rxErrs: 5,
+		},
+		drops: 9,
+		nic:   8,
+	}
+	got := errsBetween(counterSet{}, n)
+	want := errs{lost: 1, corrupt: 2 + 3 + 4, link: 8 + 5, internal: 9 + 7 + 6}
+	if got != want {
+		t.Errorf("errsBetween = %+v, want %+v", got, want)
+	}
+	if got.total() != 45 {
+		t.Errorf("total = %d, want 45", got.total())
+	}
+}
 
 // A reset re-bases from a fresh capture while the ring still holds buckets from
 // just before it, so the newest bucket must not be left behind the new origin.