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).

Also, # nocov the entire if (showProgress) branch.

Author: aitap

R/test.data.table.R

@@ -383,10 +383,11 @@ test = function(num,x,y=TRUE,error=NULL,warning=NULL,message=NULL,output=NULL,no
        }
        assign("lasttime", proc.time()[3L], parent.frame(), inherits=TRUE)  # after gc() to exclude gc() time from next test when memtest
     }, add=TRUE )
-    if (showProgress) {
+    if (showProgress) { # nocov start
       cat("\r") # notranslate: \r can't be in gettextf msg
-      catf("Running test id", numStr, "         ")   # nocov.
-    }
+      catf("Running test id %s", numStr)
+      cat("         ")   # notranslate
+    } # nocov end
     # 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
     # try(sys.source()) in test.data.table() to be run in a separate R process. That process could write out