add dry_run for run_submission() (#310)

For quick test, it might be in need of dry-run instead of just returning
after submission really take effect. For easily debug, `dry_run` is add
as a choice to make it possible to only put the input files onto
work_path but not really submitted.

While the feature requested and reviewed, it might be a question whether
a so-called dry-run should contain the step of uploading instead of just
print the file on the screen. Maybe more discussion in need?

dpdispatcher/submission.py

@@ -196,13 +196,14 @@ def bind_machine(self, machine):
             self.local_root = machine.context.temp_local_root
         return self
 
-    def run_submission(self, *, exit_on_submit=False, clean=True):
+    def run_submission(self, *, dry_run=False, exit_on_submit=False, clean=True):
         """main method to execute the submission.
         First, check whether old Submission exists on the remote machine, and try to recover from it.
         Second, upload the local files to the remote machine where the tasks to be executed.
         Third, run the submission defined previously.
         Forth, wait until the tasks in the submission finished and download the result file to local directory.
-        if exit_on_submit is True, submission will exit.
+        If dry_run is True, submission will be uploaded but not be executed and exit.
+        If exit_on_submit is True, submission will exit.
         """
         assert self.resources is not None
         if not self.belonging_jobs:
@@ -214,6 +215,10 @@ def run_submission(self, *, exit_on_submit=False, clean=True):
         else:
             dlog.info("info:check_all_finished: False")
             self.upload_jobs()
+            if dry_run is True:
+                dlog.info(f"submission succeeded: {self.submission_hash}")
+                dlog.info(f"at {self.machine.context.remote_root}")
+                return self.serialize()
             self.handle_unexpected_submission_state()
             self.submission_to_json()
             time.sleep(1)