fixup! Kucoin: Add Subscription batching

exchanges/subscription/template.go

@@ -20,13 +20,13 @@ const (
 )
 
 var (
-	errInvalidAssetExpandPairs = errors.New("subscription template containing PairSeparator with must contain either specific Asset or AssetSeparator")
-	errAssetRecords            = errors.New("subscription template did not generate the expected number of asset records")
-	errPairRecords             = errors.New("subscription template did not generate the expected number of pair records")
-	errTooManyBatchSize        = errors.New("too many BatchSize directives")
-	errAssetTemplateWithoutAll = errors.New("sub.Asset must be set to All if AssetSeparator is used in Channel template")
-	errNoTemplateContent       = errors.New("subscription template did not generate content")
-	errInvalidTemplate         = errors.New("GetSubscriptionTemplate did not return a template")
+	errInvalidAssetExpandPairs  = errors.New("subscription template containing PairSeparator with must contain either specific Asset or AssetSeparator")
+	errAssetRecords             = errors.New("subscription template did not generate the expected number of asset records")
+	errPairRecords              = errors.New("subscription template did not generate the expected number of pair records")
+	errTooManyBatchSizePerAsset = errors.New("more than one BatchSize directive inside an AssetSeparator")
+	errAssetTemplateWithoutAll  = errors.New("sub.Asset must be set to All if AssetSeparator is used in Channel template")
+	errNoTemplateContent        = errors.New("subscription template did not generate content")
+	errInvalidTemplate          = errors.New("GetSubscriptionTemplate did not return a template")
 )
 
 type tplCtx struct {
@@ -148,15 +148,21 @@ func expandTemplate(e iExchange, s *Subscription, ap assetPairs, assets asset.It
 		a := assets[i]
 		pairs := subCtx.AssetPairs[a]
 
-		batchSize := len(pairs) // Default to all pairs in one batch
+		/* Batching:
+		- We start by assuming we'll get 1 batch sized to contain all pairs. Maybe a comma-separated list, or just the asset name
+		- If a BatchSize directive is found, we expect it to come right at the end, and be followed by the batch size as a number
+		- We'll then split into N batches of that size
+		- If no batchSize was declared, but we saw a PairSeparator, then we expect to see one line per pair, so batchSize is 1
+		*/
+		batchSize := len(pairs)
 		if b := strings.Split(assetChannels, subCtx.BatchSize); len(b) > 2 {
-			return nil, fmt.Errorf("%w for %s", errTooManyBatchSize, a)
-		} else if len(b) == 2 { // If there's a batch size indicator we batch by that
+			return nil, fmt.Errorf("%w for %s", errTooManyBatchSizePerAsset, a)
+		} else if len(b) == 2 {
 			assetChannels = b[0]
 			if batchSize, err = strconv.Atoi(strings.TrimSpace(b[1])); err != nil {
 				return nil, fmt.Errorf("%s: %w", s, common.GetTypeAssertError("int", b[1], "batchSize"))
 			}
-		} else if xpandPairs { // expanding pairs but not batching so batch size is 1
+		} else if xpandPairs {
 			batchSize = 1
 		}
 
@@ -172,6 +178,7 @@ func expandTemplate(e iExchange, s *Subscription, ap assetPairs, assets asset.It
 		pairLines := strings.Split(assetChannels, subCtx.PairSeparator)
 
 		if s.Asset != asset.Empty && len(pairLines) != len(batches) {
+			// The number of lines we get generated must match the number of pair batches we expect
 			return nil, fmt.Errorf("%w for %s: Got %d; Expected %d", errPairRecords, a, len(pairLines), len(batches))
 		}
 

exchanges/subscription/template_test.go

@@ -107,7 +107,7 @@ func TestExpandTemplates(t *testing.T) {
 	assert.ErrorIs(t, err, errPairRecords, "Should error correctly when invalid number of pair entries")
 
 	_, err = List{{Channel: "error4", Asset: asset.Spot}}.ExpandTemplates(e)
-	assert.ErrorIs(t, err, errTooManyBatchSize, "Should error correctly when too many BatchSize directives")
+	assert.ErrorIs(t, err, errTooManyBatchSizePerAsset, "Should error correctly when too many BatchSize directives")
 
 	_, err = List{{Channel: "error5", Asset: asset.Spot}}.ExpandTemplates(e)
 	assert.ErrorIs(t, err, common.ErrTypeAssertFailure, "Should error correctly when batch size isn't an int")