retry: added tests for retry loop

internal/retry/retry.go

@@ -10,7 +10,7 @@
 
 var log = repologging.Logger("repo/retry")
 
-const (
+var (
 	maxAttempts             = 10
 	retryInitialSleepAmount = 1 * time.Second
 	retryMaxSleepAmount     = 32 * time.Second

internal/retry/retry_test.go

@@ -0,0 +1,60 @@
+package retry
+
+import (
+	"errors"
+	"fmt"
+	"reflect"
+	"testing"
+	"time"
+)
+
+var (
+	errRetriable    = errors.New("retriable")
+	errNonRetriable = errors.New("non-retriable")
+)
+
+func isRetriable(e error) bool {
+	return e == errRetriable
+}
+
+func TestRetry(t *testing.T) {
+	retryInitialSleepAmount = 10 * time.Millisecond
+	retryMaxSleepAmount = 20 * time.Millisecond
+	maxAttempts = 3
+
+	cnt := 0
+
+	cases := []struct {
+		desc      string
+		f         func() (interface{}, error)
+		want      interface{}
+		wantError error
+	}{
+		{"success-nil", func() (interface{}, error) { return nil, nil }, nil, nil},
+		{"success", func() (interface{}, error) { return 3, nil }, 3, nil},
+		{"retriable-succeeds", func() (interface{}, error) {
+			cnt++
+			if cnt < 2 {
+				return nil, errRetriable
+			}
+			return 4, nil
+		}, 4, nil},
+		{"retriable-never-succeeds", func() (interface{}, error) { return nil, errRetriable }, nil, fmt.Errorf("unable to complete retriable-never-succeeds despite 3 retries")},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.desc, func(t *testing.T) {
+			tc := tc
+			t.Parallel()
+
+			got, err := WithExponentialBackoff(tc.desc, tc.f, isRetriable)
+			if !reflect.DeepEqual(err, tc.wantError) {
+				t.Errorf("invalid error %q, wanted %q", err, tc.wantError)
+			}
+
+			if got != tc.want {
+				t.Errorf("invalid value %v, wanted %v", got, tc.want)
+			}
+		})
+	}
+}