[tests] Tidy up forknotify.py

Author: jnewbery

test/functional/forknotify.py

@@ -4,56 +4,40 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test the -alertnotify option."""
 import os
-import time
 
 from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import assert_equal, wait_until
 
 class ForkNotifyTest(BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 2
 
     def setup_network(self):
         self.alert_filename = os.path.join(self.options.tmpdir, "alert.txt")
-        with open(self.alert_filename, 'w', encoding='utf8'):
-            pass  # Just open then close to create zero-length file
-        self.extra_args = [["-blockversion=2", "-alertnotify=echo %s >> \"" + self.alert_filename + "\""],
+        self.extra_args = [["-alertnotify=echo %%s >> %s" % self.alert_filename],
                            ["-blockversion=211"]]
         super().setup_network()
 
     def run_test(self):
-        # Mine 51 up-version blocks
+        # Mine 51 up-version blocks. -alertnotify should trigger on the 51st.
         self.nodes[1].generate(51)
         self.sync_all()
-        # -alertnotify should trigger on the 51'st,
-        # but mine and sync another to give
-        # -alertnotify time to write
-        self.nodes[1].generate(1)
-        self.sync_all()
 
         # Give bitcoind 10 seconds to write the alert notification
-        timeout = 10.0
-        while timeout > 0:
-            if os.path.exists(self.alert_filename) and os.path.getsize(self.alert_filename):
-                break
-            time.sleep(0.1)
-            timeout -= 0.1
-        else:
-            assert False, "-alertnotify did not warn of up-version blocks"
+        wait_until(lambda: os.path.isfile(self.alert_filename) and os.path.getsize(self.alert_filename), timeout=10)
 
         with open(self.alert_filename, 'r', encoding='utf8') as f:
             alert_text = f.read()
 
         # Mine more up-version blocks, should not get more alerts:
-        self.nodes[1].generate(1)
-        self.sync_all()
-        self.nodes[1].generate(1)
+        self.nodes[1].generate(2)
         self.sync_all()
 
         with open(self.alert_filename, 'r', encoding='utf8') as f:
             alert_text2 = f.read()
 
-        if alert_text != alert_text2:
-            raise AssertionError("-alertnotify excessive warning of up-version blocks")
+        self.log.info("-alertnotify should not continue notifying for more unknown version blocks")
+        assert_equal(alert_text, alert_text2)
 
 if __name__ == '__main__':
     ForkNotifyTest().main()