add regression test self-tests

check.t

@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/check.t,v 1.158 2008/03/05 18:21:44 tg Exp $
+# $MirOS: src/bin/mksh/check.t,v 1.159 2008/03/23 20:43:51 tg Exp $
 # $OpenBSD: bksl-nl.t,v 1.2 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: history.t,v 1.5 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: read.t,v 1.3 2003/03/10 03:48:16 david Exp $
@@ -15,6 +15,32 @@ stdin:
 	echo $KSH_VERSION
 name: KSH_VERSION
 ---
+name: selftest-1
+description:
+	Regression test self-testing
+stdin:
+	print ${foo:-baz}
+expected-stdout:
+	baz
+---
+name: selftest-2
+description:
+	Regression test self-testing
+env-setup: !foo=bar!
+stdin:
+	print ${foo:-baz}
+expected-stdout:
+	bar
+---
+name: selftest-3
+description:
+	Regression test self-testing
+env-setup: !ENV=fnord!
+stdin:
+	print "<$ENV>"
+expected-stdout:
+	<fnord>
+---
 name: alias-1
 description:
 	Check that recursion is detected/avoided in aliases.