test(talk): fetch rooms once before checking modifiedSince

Talk captures the timestamp it returns in X-Nextcloud-Talk-Modified-Before at
the start of getRooms, and only then dispatches BeforeRoomsFetchEvent, whose
listeners create the "Note to self", sample and changelog conversations for a
user seeing Talk for the first time. Those rooms end up with a lastActivity
newer than the timestamp already reported, so the test's window of "nothing was
modified since T + 2 seconds" only held while that creation finished within two
seconds. On a loaded CI runner it does not, and the returned sample rooms fail
the assertion, which is what made the matrix jobs flaky.

Fetch the rooms once before the timed sequence, so the lazy creation happens
outside the window that is checked.

Signed-off-by: Oleksandr Piskun <oleksandr2088@icloud.com>

Author: oleksandr-nc

tests/actual_tests/talk_test.py

@@ -85,6 +85,11 @@ def test_conversation_create_delete(nc):
 def test_get_conversations_modified_since(nc):
     if nc.talk.available is False:
         pytest.skip("Nextcloud Talk is not installed")
+    # Talk creates the "Note to self", sample and changelog conversations while serving a user's first
+    # rooms request, after it has captured the timestamp it reports in `X-Nextcloud-Talk-Modified-Before`.
+    # Those rooms are therefore newer than that timestamp; fetch once up front so that their creation
+    # cannot land inside the window checked below.
+    nc.talk.get_user_conversations()
     conversation = nc.talk.create_conversation(talk.ConversationType.GROUP, "admin")
     try:
         conversations = nc.talk.get_user_conversations()
@@ -102,6 +107,8 @@ def test_get_conversations_modified_since(nc):
 async def test_get_conversations_modified_since_async(anc):
     if await anc.talk.available is False:
         pytest.skip("Nextcloud Talk is not installed")
+    # see the comment in the sync test above
+    await anc.talk.get_user_conversations()
     conversation = await anc.talk.create_conversation(talk.ConversationType.GROUP, "admin")
     try:
         conversations = await anc.talk.get_user_conversations()