build: Run tools with available python version

tap-{gtester,driver} can be run with Python 2 or 3. Call them with
whichever is available, as this differs between Fedora and RHEL.
This avoids having to build-depend on both python 2 and 3.

Make the remaining tools bilingual and switch them to Python 3 by
default.

Drop the python3 runtime hack from test-bots, as it is now always
invoked with Python 3.

Closes cockpit-project#9525

Makefile.am

@@ -261,15 +261,15 @@ AM_CPPFLAGS = \
 
 AM_LDFLAGS = -Wl,--as-needed
 
-LOG_DRIVER = $(top_srcdir)/tools/tap-driver
-LOG_COMPILER = $(top_srcdir)/tools/tap-gtester
+LOG_DRIVER = $(PYTHON) $(top_srcdir)/tools/tap-driver
+LOG_COMPILER = $(PYTHON) $(top_srcdir)/tools/tap-gtester
 
 TEST_EXTENSIONS = .html .sh
-SH_LOG_DRIVER = $(top_srcdir)/tools/tap-driver
-HTML_LOG_DRIVER = $(top_srcdir)/tools/tap-driver
+SH_LOG_DRIVER = $(LOG_DRIVER)
+HTML_LOG_DRIVER = $(LOG_DRIVER)
 HTML_TEST_SERVER = $(builddir)/test-server
 
-HTML_LOG_COMPILER = $(top_srcdir)/test/common/tap-cdp --strip=$(top_srcdir)/ -- $(HTML_TEST_SERVER)
+HTML_LOG_COMPILER = $(PYTHON) $(top_srcdir)/test/common/tap-cdp --strip=$(top_srcdir)/ -- $(HTML_TEST_SERVER)
 
 VALGRIND_ARGS = --trace-children=yes --quiet --error-exitcode=33 \
 	--suppressions=valgrind-suppressions --gen-suppressions=all \

bots/test-bots

@@ -1,5 +1,4 @@
-#!/usr/bin/env python
-# -*- coding: utf-8 -*-
+#!/usr/bin/python3
 
 # This file is part of Cockpit.
 #
@@ -18,10 +17,8 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with Cockpit; If not, see <http://www.gnu.org/licenses/>.
 
-import errno
 import glob
 import imp
-import platform
 import os
 import sys
 import unittest
@@ -47,16 +44,5 @@ def main():
         return 0
     return 1
 
-# Because these tests are invoked on systems without python3 but the bots
-# are written in python3, we skip the tests on systems without python3 available
 if __name__ == '__main__':
-    if platform.python_version()[0] == '2':
-        try:
-            args = [ "python3", __file__ ] + sys.argv
-            os.execvp(args[0], args)
-        except OSError as ex:
-            if ex.errno == errno.ENOENT:
-                sys.stdout.write("1..1\nok 1 bots tests # SKIP no python3\n")
-                sys.exit(0)
-    else:
-        sys.exit(main())
+    sys.exit(main())

configure.ac

@@ -535,6 +535,10 @@ else
 fi
 AC_MSG_RESULT($enable_strict)
 
+# Python version; prefer python3
+m4_define_default([_AM_PYTHON_INTERPRETER_LIST], [python3 python2 python])
+AM_PATH_PYTHON([2.7])
+
 # Generate
 #
 

test/common/tap-cdp

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 
 #
 # Copyright (C) 2017 Red Hat, Inc.
@@ -63,6 +63,7 @@ if not cdp.get_browser_path():
 server = subprocess.Popen(opts.server,
                           stdout=subprocess.PIPE,
                           stdin=subprocess.PIPE,
+                          universal_newlines=True,
                           close_fds=True)
 
 address = server.stdout.readline()
@@ -95,9 +96,9 @@ for t, message in cdp.read_log():
 
     # TAP lines go to stdout, everything else to stderr
     if tap_line_re.match(message):
-        print(message.encode('utf-8'))
+        print(message)
     else:
-        print(message.encode('utf-8'), file=sys.stderr)
+        print(message, file=sys.stderr)
 
 
 server.terminate()

tools/tap-driver

@@ -1,5 +1,5 @@
-#!/usr/bin/python2
-# This can also be run with Python 3.
+#!/usr/bin/python3
+# This can also be run with Python 2.
 
 # Copyright (C) 2013 Red Hat, Inc.
 #

tools/tap-gtester

@@ -1,5 +1,5 @@
-#!/usr/bin/python2
-# This can also be run with Python 3.
+#!/usr/bin/python3
+# This can also be run with Python 2.
 
 # Copyright (C) 2014 Red Hat, Inc.
 #