fix: allow rate limit of 0

We have a special case check for rate limits of 0 in some areas
of the code. Eventually I would like to remove those so I'm
going to set the rate limit of 0 as a valid rate limit which
allows no events.

internal/ratelimit/burst.go

@@ -37,7 +37,7 @@ func NewBurstLimiter(r conf.Rate) *BurstLimiter {
 
 	e := r.Events
 	if e <= 0 {
-		e = 1
+		e = 0
 	}
 
 	// BurstLimiter will have an initial token bucket of size `e`. It will

internal/ratelimit/burst_test.go

@@ -150,9 +150,9 @@ func TestBurstLimiter(t *testing.T) {
 				},
 			},
 
-			// zero value for Events = 1 event per second
+			// 1 event per second
 			{
-				cfg: conf.Rate{Events: 0, OverTime: time.Second},
+				cfg: conf.Rate{Events: 1, OverTime: time.Second},
 				now: now,
 				evts: []event{
 					{true, now, 0},
@@ -162,9 +162,9 @@ func TestBurstLimiter(t *testing.T) {
 				},
 			},
 
-			// zero value for both Events and OverTime = 1 event per hour.
+			// 1 events per second and OverTime = 1 event per hour.
 			{
-				cfg: conf.Rate{Events: 0, OverTime: 0},
+				cfg: conf.Rate{Events: 1, OverTime: 0},
 				now: now,
 				evts: []event{
 					{true, now, 0},
@@ -173,6 +173,31 @@ func TestBurstLimiter(t *testing.T) {
 					{true, now.Add(time.Hour * 2), 0},
 				},
 			},
+
+			// zero value for Events = 0 event per second
+			{
+				cfg: conf.Rate{Events: 0, OverTime: time.Second},
+				now: now,
+				evts: []event{
+					{false, now, 0},
+					{false, now.Add(-time.Second), 0},
+					{false, now.Add(time.Second), 0},
+					{false, now.Add(time.Second * 2), 0},
+				},
+			},
+
+			// zero value for both Events and OverTime = 1 event per hour.
+			{
+				cfg: conf.Rate{Events: 0, OverTime: 0},
+				now: now,
+				evts: []event{
+					{false, now, 0},
+					{false, now.Add(time.Hour - time.Second), 0},
+					{false, now.Add(-time.Hour), 0},
+					{false, now.Add(time.Hour), 0},
+					{false, now.Add(time.Hour * 2), 0},
+				},
+			},
 		}
 
 		for _, tc := range cases {