Add: use random port to run qvarn backend during tests

This is not 100% reliable, due to a race condition: it's possible for
the test code to pick a free port, and someone else to immediately
reserve the port before Qvarn does. But it's too unlikely to be a real
problem, for tests.

3 files changed, 30 insertions, 3 deletions

diff --git a/randport b/randport
new file mode 100755
index 0000000..d523401
--- /dev/null
+++ b/randport
@@ -0,0 +1,28 @@
+#!/usr/bin/python3
+#
+# Copyright (C) 2017  Lars Wirzenius
+#
+# Pick a random port that is free to be listened on. For testing.
+
+
+import errno
+import random
+import socket
+import sys
+
+
+MAX = 1000
+for i in range(MAX):
+    port = random.randint(1025, 2**15-1)
+    s = socket.socket()
+    try:
+        s.bind(('0.0.0.0', port))
+    except OSError as e:
+        if e.errno == errno.EADDRINUSE:
+            continue
+        raise
+    break
+else:
+    sys.stderr.write("Can't find a free port\n")
+    sys.exit(1)
+sys.stdout.write('{}\n'.format(port))
diff --git a/yarns/900-implements.yarn b/yarns/900-implements.yarn
index 7837f8c..d6abb7a 100644
--- a/yarns/900-implements.yarn
+++ b/yarns/900-implements.yarn
@@ -17,9 +17,7 @@ Start a Qvarn running in the background.
     vars['api.log'] = 'qvarn.log'
     vars['gunicorn3.log'] = 'gunicorn3.log'
     vars['pid-file'] = 'pid'
-    # FIXME: It would be good for the test suite to pick a random free
-    # port. But that's not simple.
-    vars['port'] = 12765
+    vars['port'] = cliapp.runcmd([os.path.join(srcdir, 'randport' )]).strip()
     vars['url'] = 'http://127.0.0.1:{}'.format(vars['port'])
     config = {
         'log': [
diff --git a/yarns/lib.py b/yarns/lib.py
index 37ffc21..4b0f250 100644
--- a/yarns/lib.py
+++ b/yarns/lib.py
@@ -35,6 +35,7 @@ vars = Variables(datadir)
 
 
 def get(url, headers=None):
+    print('get: url={} headers={}'.format(url, headers))
     r = requests.get(url, headers=headers)
     return r.status_code, r.text