beaconmock: remove backoff dependency (#2089)

Remove `gopkg.in/cenkalti/backoff.v1` direct dependency by removing its usage in `headproducer_internal_test.go`. Though it is still present as an indirect dependency since `sse/v2` uses it.

category: refactor
ticket: #2083

go.mod

@@ -44,7 +44,6 @@ require (
 	golang.org/x/time v0.3.0
 	golang.org/x/tools v0.8.0
 	google.golang.org/protobuf v1.30.0
-	gopkg.in/cenkalti/backoff.v1 v1.1.0
 )
 
 require (
@@ -177,6 +176,7 @@ require (
 	golang.org/x/text v0.9.0 // indirect
 	golang.org/x/xerrors v0.0.0-20220907171357-04be3eba64a2 // indirect
 	google.golang.org/appengine v1.6.7 // indirect
+	gopkg.in/cenkalti/backoff.v1 v1.1.0 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect

testutil/beaconmock/headproducer_internal_test.go

@@ -15,7 +15,6 @@ import (
 	eth2p0 "github.com/attestantio/go-eth2-client/spec/phase0"
 	"github.com/r3labs/sse/v2"
 	"github.com/stretchr/testify/require"
-	"gopkg.in/cenkalti/backoff.v1"
 
 	"github.com/obolnetwork/charon/app/errors"
 )
@@ -72,21 +71,26 @@ func TestHeadProducer(t *testing.T) {
 				requiredTopics[topic] = true
 			}
 
-			client := sse.NewClient(addr, func(c *sse.Client) {
-				c.ResponseValidator = func(c *sse.Client, resp *http.Response) error {
-					require.Equal(t, test.statusCode, resp.StatusCode)
+			client := sse.NewClient(addr,
+				func(c *sse.Client) {
+					c.ResponseValidator = func(c *sse.Client, resp *http.Response) error {
+						require.Equal(t, test.statusCode, resp.StatusCode)
 
-					if resp.StatusCode == http.StatusInternalServerError {
-						data, err := io.ReadAll(resp.Body)
-						require.NoError(t, err)
-						require.Contains(t, string(data), "unknown topic")
+						if resp.StatusCode == http.StatusInternalServerError {
+							data, err := io.ReadAll(resp.Body)
+							require.NoError(t, err)
+							require.Contains(t, string(data), "unknown topic")
 
-						return backoff.Permanent(unsupportedTopicErr)
-					}
+							return unsupportedTopicErr
+						}
 
-					return nil
-				}
-			})
+						return nil
+					}
+				},
+				func(c *sse.Client) {
+					c.ReconnectStrategy = StopBackOff{}
+				},
+			)
 
 			ctx, cancel := context.WithCancel(context.Background())
 			defer cancel()
@@ -117,3 +121,19 @@ func TestHeadProducer(t *testing.T) {
 		})
 	}
 }
+
+// Refer https://github.com/cenkalti/backoff/blob/v4/backoff.go#L46 for the following snippet.
+// We don't need the full dependency since we don't want these tests to support exponential backoff.
+// We want simple, fast tests where a single event is sent by the server and is intercepted by the client, or
+// it produces an error.
+
+// Stop indicates that no more retries should be made for use in NextBackOff().
+const Stop time.Duration = -1
+
+// StopBackOff is a fixed backoff policy that always returns backoff.Stop for
+// NextBackOff(), meaning that the operation should never be retried.
+type StopBackOff struct{}
+
+func (b StopBackOff) Reset() {}
+
+func (b StopBackOff) NextBackOff() time.Duration { return Stop }