First cookbook example for the docs: Hello World in C.

Documentation/cookbook/hello/test.do

@@ -0,0 +1,12 @@
+# Make sure everything has been built before we start
+redo-ifchange all
+
+# Ensure that the hello program, when run, says
+# hello like we expect.
+if ./hello | grep -i 'hello' >/dev/null; then
+    echo "success" >&2
+    exit 0
+else
+    echo "missing 'hello' message!" >&2
+    exit 1
+fi