test(io): move utility function to util.py

The function `match_log` should be in `util.py` so it can be reused
in other modules.

Signed-off-by: Taimoor Zaeem <taimoorzaeem@gmail.com>

test/io/util.py

@@ -1,3 +1,4 @@
+import re
 import threading
 import jwt
 
@@ -21,6 +22,19 @@ class Thread(threading.Thread):
             raise self._exception
 
 
+def match_log(output, matchers):
+    ito = iter(output)
+    itm = iter(matchers)
+    nextMatcher = next(itm, None)
+    while nextMatcher is not None and (line := next(ito, None)) is not None:
+        if re.match(nextMatcher, line) is not None:
+            nextMatcher = next(itm, None)
+    if nextMatcher is not None:
+        raise AssertionError(
+            f"Expected log line matching {nextMatcher} not found in output"
+        )
+
+
 def authheader(token):
     "Bearer token HTTP authorization header."
     return {"Authorization": f"Bearer {token}"}