fix: retry precommit mysql lock conflicts

internal/storage/mysql/db_test.go

@@ -0,0 +1,38 @@
+package mysql
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"testing"
+
+	driver "github.com/go-sql-driver/mysql"
+)
+
+func TestRetryableTransactionErrorOnlyMatchesPreCommitLockFailures(t *testing.T) {
+	tests := []struct {
+		name string
+		err  error
+		want bool
+	}{
+		{name: "deadlock", err: &driver.MySQLError{Number: 1213}, want: true},
+		{name: "lock wait timeout", err: fmt.Errorf("wrapped: %w", &driver.MySQLError{Number: 1205}), want: true},
+		{name: "duplicate key", err: &driver.MySQLError{Number: 1062}, want: false},
+		{name: "application error", err: errors.New("validation failed"), want: false},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			if got := retryableTransactionError(test.err); got != test.want {
+				t.Fatalf("retryableTransactionError()=%v want %v", got, test.want)
+			}
+		})
+	}
+}
+
+func TestWaitTransactionRetryHonorsCancellation(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+	if err := waitTransactionRetry(ctx, 0); !errors.Is(err, context.Canceled) {
+		t.Fatalf("waitTransactionRetry()=%v want context canceled", err)
+	}
+}