test.data.table: fix arguments to catf()

This ensures that interactive test.data.table() prints the test numbers
while running (and avoids an error due to options(warn=2) in the middle
of tests.Rraw).

Author: aitap

R/test.data.table.R

@@ -385,7 +385,8 @@ test = function(num,x,y=TRUE,error=NULL,warning=NULL,message=NULL,output=NULL,no
     }, add=TRUE )
     if (showProgress) {
       cat("\r") # notranslate: \r can't be in gettextf msg
-      catf("Running test id", numStr, "         ")   # nocov.
+      catf("Running test id %s", numStr) # nocov.
+      cat("         ")   # notranslate
     }
     # See PR #4090 for comments about change here in Dec 2019.
     # If a segfault error occurs in future and we'd like to know after which test, then arrange for the