From 4a00192ab6a84fb76391f844a8b2e1978b543d1e Mon Sep 17 00:00:00 2001
From: Luca Toniolo <10792599+grandixximo@users.noreply.github.com>
Date: Sat, 19 Sep 2026 22:06:38 +1000
Subject: [PATCH] tests: close the idle-detection hole in the G28.2 sequencing
 test

The rejected G28.2 P99 puts task through its ERROR path, which reports
DONE/IDLE with the resynch still on the interp list. The next MDI sent
in that window is parked in the MDI queue, and a queued MDI also reads
as DONE/IDLE, so wait_idle() returned before the move ran and the test
read X while it was still 0. One slow task cycle on a loaded CI runner
is enough to open the window.

wait_idle() now also requires queued_mdi_commands == 0, and the recovery
check waits for X to reach 2 instead of for idle.

Fixes #4569
---
 tests/interp/g28.2/sequencing/test-ui.py | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/tests/interp/g28.2/sequencing/test-ui.py b/tests/interp/g28.2/sequencing/test-ui.py
index 67c05322a67..87c68638802 100755
--- a/tests/interp/g28.2/sequencing/test-ui.py
+++ b/tests/interp/g28.2/sequencing/test-ui.py
@@ -33,7 +33,21 @@ def wait_idle(timeout=5.0):
     t0 = time.time()
     while time.time() - t0 < timeout:
         poll()
-        if s.exec_state == linuxcnc.EXEC_DONE and s.interp_state == linuxcnc.INTERP_IDLE:
+        # A queued MDI command shows as DONE/IDLE until task takes it off
+        # the queue, so it has to be counted too.
+        if (s.exec_state == linuxcnc.EXEC_DONE
+                and s.interp_state == linuxcnc.INTERP_IDLE
+                and s.queued_mdi_commands == 0):
+            return True
+        time.sleep(0.01)
+    return False
+
+
+def wait_x(expected, timeout=5.0):
+    t0 = time.time()
+    while time.time() - t0 < timeout:
+        poll()
+        if near(s.position[0], expected):
             return True
         time.sleep(0.01)
     return False
@@ -93,11 +107,10 @@ def near(a, b, tol=0.001):
 if s.task_mode != mode_before:
     fail("task_mode after invalid Pn is {}, expected {} (MDI)".format(s.task_mode, mode_before))
 
+# The rejected G28.2 leaves a resynch on the interp list; task parks the
+# next MDI behind it, so wait for the move itself rather than for idle.
 c.mdi("G0 X2")
-if not wait_idle():
-    fail("recovery MDI command after invalid Pn did not settle")
-poll()
-if not near(s.position[0], 2.0):
+if not wait_x(2.0):
     fail("MDI command after an invalid Pn was rejected -- task_mode stuck (X stayed at {})".format(s.position[0]))
 print("PASS: an invalid Pn does not leave task_mode stuck")