Update 'advanced' test to contain pass-able code

src/bar/baz-advanced/test

@@ -1,8 +1,22 @@
 #!/bin/bash
 
-jat__pstartt "jattool sessid"
-    jat__cmd -h "sessid subcommand returns zero" \
-        jat sessid
-    jat__cmd -h "sessid subcommand prints something" \
-        test -n "$(jattool sessid)"
+jattool() {
+    #
+    # Run jattool safely
+    #
+    (
+        export PRETTY=plain
+        command jattool "$@"
+    )
+}
+
+jat__pstartt "jattool"
+    jat__cmd -h "returns two" \
+        -S 2 -e jattool.err -o jattool.out \
+        jattool
+    jat__cmd -h "prints nothing to stdout" \
+        -S 1 \
+        test -s jattool.out
+    jat__cmd -h "prints something to stderr" \
+        test -s jattool.err
 jat__pend