tests/periph_rtt: add automatic testing script

tests/periph_rtt/tests/01-run.py

+#!/usr/bin/env python3
+
+# Copyright (C) 2019 Inria
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+
+import sys
+import time
+from testrunner import run
+
+
+PRECISION = 0.05  # 5%
+MAX_HELLOS = 5
+
+
+def testfunc(child):
+    child.expect(r'This test will display \'Hello\' every (\d+) seconds')
+    period = int(child.match[1])
+    child.expect_exact('Initializing the RTT driver')
+    child.expect(r'RTT now: \d+')
+    child.expect(r'Setting initial alarm to now \+ {} s \(\d+\)'
+                 .format(period))
+    child.expect_exact('Done setting up the RTT, wait for many Hellos')
+    start = time.time()
+    for _ in range(MAX_HELLOS):
+        child.expect_exact('Hello\r\n', timeout=period + 1)
+
+    # Verify timings
+    elapsed = time.time() - start
+    assert elapsed > (MAX_HELLOS * period * (1 - PRECISION))
+    assert elapsed < (MAX_HELLOS * period * (1 + PRECISION))
+
+
+if __name__ == "__main__":
+    sys.exit(run(testfunc))