11/16: marionette: Add a callback arguments to wait-for-screen-text.

[guix-commits]

apteryx pushed a commit to branch master
in repository guix.

commit 133901a396cf81aa1dcb35586e77a5a78475c4c7
Author: Maxim Cournoyer <maxim.cournoyer@gmail.com>
AuthorDate: Fri Sep 23 00:23:47 2022 -0400

    marionette: Add a callback arguments to wait-for-screen-text.
    
    * gnu/build/marionette.scm (wait-for-screen-text): New 'pre-action' and
    'post-action' arguments.  Update doc.  Call the procedures before and after
    the OCR occurs, respectively.
---
 gnu/build/marionette.scm | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/gnu/build/marionette.scm b/gnu/build/marionette.scm
index 6f373f87b6..f4b219e842 100644
--- a/gnu/build/marionette.scm
+++ b/gnu/build/marionette.scm
@@ -331,11 +331,15 @@ if it is not needed."
 (define* (wait-for-screen-text marionette predicate
                                #:key
                                (ocr "ocrad")
-                               (timeout 30))
+                               (timeout 30)
+                               pre-action
+                               post-action)
   "Wait for TIMEOUT seconds or until the screen text on MARIONETTE matches
 PREDICATE, whichever comes first.  Raise an error when TIMEOUT is exceeded.
 The error contains the recognized text along the preserved file name of the
-screen dump, which is relative to the current working directory."
+screen dump, which is relative to the current working directory.  If
+PRE-ACTION is provided, it should be a thunk to call before each OCR attempt.
+Likewise for POST-ACTION, except it runs at the end of a successful OCR."
   (define start
     (car (gettimeofday)))
 
@@ -353,7 +357,9 @@ screen dump, which is relative to the current working 
directory."
           (error "'wait-for-screen-text' timeout"
                  'ocr-text: last-text
                  'screendump: screendump-backup))
-        (let* ((text screendump (marionette-screen-text marionette #:ocr ocr))
+        (let* ((_ (and (procedure? pre-action) (pre-action)))
+               (text screendump (marionette-screen-text marionette #:ocr ocr))
+               (_ (and (procedure? post-action) (post-action)))
                (result (predicate text)))
           (cond (result
                  (delete-file screendump)