Fix regression

In `org-babel-jupyter-initiate-session-by-key`, the function to
disassociate a client from a :session was added to the
`current-buffer`s value of `kill-buffer-hook` but it should be added
to the REPL buffer's value of that hook.

fixes #240

* ob-jupyter.el
(org-babel-jupyter-initiate-session-by-key): Add to the local value of
`kill-buffer-hook` in the REPL's buffer.

* test/jupyter-test.el
(org-babel-jupyter-initiate-session-by-key): New test.

CHANGELOG.org

@@ -1,5 +1,10 @@
 * master
 
+- Fixed a regression that appears when executing an =org-mode= source
+  block of a previously created session.  A new connection to the
+  session was being created before execution instead of using the old
+  connection.  See #240.
+
 - Fixed regression due to uppercase characters in kernel language
   names, e.g. R.  =emacs-jupyter= would not work at all with language
   specific features.

ob-jupyter.el

@@ -371,8 +371,9 @@ the host."
                     (org-babel-jupyter-parse-session session)
                     kernel))
       (puthash key client org-babel-jupyter-session-clients)
-      (let ((forget-client (lambda () (remhash key org-babel-jupyter-session-clients))))
-        (add-hook 'kill-buffer-hook forget-client nil t)))
+      (jupyter-with-repl-buffer client
+        (let ((forget-client (lambda () (remhash key org-babel-jupyter-session-clients))))
+          (add-hook 'kill-buffer-hook forget-client nil t))))
     (oref client buffer)))
 
 (defun org-babel-jupyter-initiate-session (&optional session params)

test/jupyter-test.el

@@ -1900,6 +1900,27 @@ next(x"))))))
     (should (org-babel-jupyter-session-p session))
     (should (equal (org-babel-jupyter-session-name session) "foo/bar"))))
 
+(ert-deftest org-babel-jupyter-initiate-session-by-key ()
+  :tags '(org)
+  (jupyter-org-test
+   (let ((session (make-temp-name "jupyter")))
+     (save-excursion
+       (insert
+        (format "#+begin_src jupyter-python :session %s\n1+1\n#+end_src\n"
+                session)))
+     (let* ((params (nth 2 (org-babel-get-src-block-info)))
+            (key (org-babel-jupyter-session-key params)))
+       (should-not (gethash key org-babel-jupyter-session-clients))
+       (let ((buffer (org-babel-jupyter-initiate-session-by-key
+                      session params))
+             (client (gethash key org-babel-jupyter-session-clients)))
+         (should (bufferp buffer))
+         (should client)
+         (should (object-of-class-p client 'jupyter-repl-client))
+         (should (eq buffer (oref client buffer)))
+         (jupyter-test-kill-buffer buffer)
+         (should-not (gethash key org-babel-jupyter-session-clients)))))))
+
 (ert-deftest ob-jupyter-no-results ()
   :tags '(org)
   (jupyter-org-test-src-block "1 + 1;" ""))