test(cram): dir contents of a cram test (ocaml#12004)

Signed-off-by: Rudi Grinberg <[email protected]>

Author: rgrinberg

test/blackbox-tests/test-cases/cram/test-dir-contents.t

@@ -0,0 +1,18 @@
+Demonstrate the files and directories listed in a cram test:
+
+  $ cat >test.t <<EOF
+  >   $ find . | sort
+  > EOF
+
+  $ dune runtest test.t
+  File "test.t", line 1, characters 0-0:
+  Error: Files _build/default/test.t and _build/default/test.t.corrected
+  differ.
+  [1]
+
+  $ dune promote
+  Promoting _build/default/test.t.corrected to test.t.
+
+  $ cat test.t
+    $ find . | sort
+    .