[RPC] Added a test showing the current promotion capabilities

Signed-off-by: Ambre Austen Suhamy <[email protected]>

Author: ElectreAAS

test/blackbox-tests/test-cases/watching/direct-promotion.t

@@ -11,9 +11,9 @@ The test expectedly fails (see errors at the end of this file)
   $ build "(alias my_test)"
   Failure
 
-Promotion works even with a running RPC server.
+Promotion happens on the running RPC server.
   $ dune promote
-  Promoting _build/default/my_test.t.corrected to my_test.t.
+  Success
 
   $ build "(alias my_test)"
   Success
@@ -23,4 +23,5 @@ Promotion works even with a running RPC server.
   Error: Files _build/default/my_test.t and _build/default/my_test.t.corrected
   differ.
   Had 1 error, waiting for filesystem changes...
+  Promoting _build/default/my_test.t.corrected to my_test.t.
   Success, waiting for filesystem changes...