- fix bug where we did not reject invalid classes like '[[:alpha'
- debloat while at it:
   text    data     bss     dec     hex filename
   1554       0      19    1573     625 tr.o.oorig
   1357       0      16    1373     55d tr.o
diff --git a/testsuite/tr/tr-rejects-wrong-class b/testsuite/tr/tr-rejects-wrong-class
new file mode 100644
index 0000000..9753936
--- /dev/null
+++ b/testsuite/tr/tr-rejects-wrong-class
@@ -0,0 +1,19 @@
+echo t12esting | tr -d '[[:alpha:]]' > logfile.gnu
+echo t12esting | tr -d '[:alpha:]'  >> logfile.gnu
+echo t12esting | tr -d '[[:alpha:]' >> logfile.gnu
+echo t12esting | tr -d '[[:alpha:' >> logfile.gnu
+echo t12esting | tr -d '[[:alpha' >> logfile.gnu
+echo t12esting | tr -d '[:alpha:]' >> logfile.gnu
+echo t12esting | tr -d '[:alpha:' >> logfile.gnu
+echo t12esting | tr -d '[:alpha' >> logfile.gnu
+
+echo t12esting | busybox tr -d '[[:alpha:]]' > logfile.bb
+echo t12esting | busybox tr -d '[:alpha:]'  >> logfile.bb
+echo t12esting | busybox tr -d '[[:alpha:]' >> logfile.bb
+echo t12esting | busybox tr -d '[[:alpha:' >> logfile.bb
+echo t12esting | busybox tr -d '[[:alpha' >> logfile.bb
+echo t12esting | busybox tr -d '[:alpha:]' >> logfile.bb
+echo t12esting | busybox tr -d '[:alpha:' >> logfile.bb
+echo t12esting | busybox tr -d '[:alpha' >> logfile.bb
+
+diff -u logfile.gnu logfile.bb