test: make it possible to use pytest-style test fixtures

Currently all binaries must be available or no tests will be executed.
This is inconvenient if you just want to test a single binary (e.g.
text2pcap) without having to build epan. The problem is essentially that
tests lack dependency annotations.

To solve this problem, add the required dependencies as parameters to
each test (so-called 'fixtures' in pytest). Skip a test if a binary
(such as tshark) is unavailable. As a demonstration, suite_dissection.py
is converted. Over time, tests should no longer depend on config.py due
to explicit dependencies fixtures (listed in fixtures_ws.py).

Since the unittest module does not support such dependency injections,
create a small glue for use with pytest and an (incomplete) emulation
layer for use with test.py.

Tested with pytest 3.8.2 + Python 3.7.0 and pytest 3.0.3 + Python 3.4.3.
Python 2.7 is not supported and will fail. Test commands:

    ~/wireshark/test/test.py -p ~/build/run
    WS_BIN_PATH=~/build/run pytest ~/wireshark/test -ra

Change-Id: I6dc8c28f5c8b7bbc8f4c04838e9bf085cd22eb0b
Ping-Bug: 14949
Reviewed-on: https://code.wireshark.org/review/30220
Tested-by: Petri Dish Buildbot
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Reviewed-by: Anders Broman <a.broman58@gmail.com>

1 files changed, 174 insertions, 0 deletions

diff --git a/test/fixtures_ws.py b/test/fixtures_ws.py
new file mode 100644
index 0000000000..29b119ba67
--- /dev/null
+++ b/test/fixtures_ws.py
@@ -0,0 +1,174 @@
+#
+# -*- coding: utf-8 -*-
+# Wireshark tests
+#
+# Copyright (c) 2018 Peter Wu <peter@lekensteyn.nl>
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+'''Fixtures that are specific to Wireshark.'''
+
+import logging
+import os
+import re
+import subprocess
+import sys
+import tempfile
+import types
+
+import fixtures
+import config
+import subprocesstest
+
+
+@fixtures.fixture(scope='session')
+def program_path():
+    # XXX stop using config
+    return config.program_path
+
+
+@fixtures.fixture(scope='session')
+def program(program_path):
+    def resolver(name):
+        dotexe = ''
+        if sys.platform.startswith('win32'):
+            dotexe = '.exe'
+        path = os.path.normpath(os.path.join(program_path, name + dotexe))
+        if not os.access(path, os.X_OK):
+            fixtures.skip('Program %s is not available' % (name,))
+        return path
+    return resolver
+
+
+@fixtures.fixture(scope='session')
+def cmd_capinfos(program):
+    return program('capinfos')
+
+
+@fixtures.fixture(scope='session')
+def cmd_dumpcap(program):
+    return program('dumpcap')
+
+
+@fixtures.fixture(scope='session')
+def cmd_mergecap(program):
+    return program('mergecap')
+
+
+@fixtures.fixture(scope='session')
+def cmd_rawshark(program):
+    return program('rawshark')
+
+
+@fixtures.fixture(scope='session')
+def cmd_tshark(program):
+    return program('tshark')
+
+
+@fixtures.fixture(scope='session')
+def cmd_text2pcap(program):
+    return program('text2pcap')
+
+
+@fixtures.fixture(scope='session')
+def cmd_wireshark(program):
+    return program('wireshark')
+
+
+@fixtures.fixture(scope='session')
+def features(cmd_tshark):
+    '''Returns an object describing available features in tshark.'''
+    try:
+        # XXX stop using config
+        tshark_v = subprocess.check_output(
+            (cmd_tshark, '--version'),
+            stderr=subprocess.PIPE,
+            universal_newlines=True,
+            env=config.baseEnv()
+        )
+        tshark_v = re.sub(r'\s+', ' ', tshark_v)
+    except subprocess.CalledProcessError as ex:
+        logging.warning('Failed to detect tshark features: %s', ex)
+        tshark_v = ''
+    gcry_m = re.search(r'with +Gcrypt +([0-9]+\.[0-9]+)', tshark_v)
+    return types.SimpleNamespace(
+        have_lua='with Lua' in tshark_v,
+        have_nghttp2='with nghttp2' in tshark_v,
+        have_kerberos='with MIT Kerberos' in tshark_v or 'with Heimdal Kerberos' in tshark_v,
+        have_libgcrypt16=gcry_m and float(gcry_m.group(1)) >= 1.6,
+        have_libgcrypt17=gcry_m and float(gcry_m.group(1)) >= 1.7,
+    )
+
+
+@fixtures.fixture(scope='session')
+def dirs():
+    '''Returns fixed directories containing test input.'''
+    this_dir = os.path.dirname(__file__)
+    return types.SimpleNamespace(
+        baseline_dir=os.path.join(this_dir, 'baseline'),
+        capture_dir=os.path.join(this_dir, 'captures'),
+        config_dir=os.path.join(this_dir, 'config'),
+        key_dir=os.path.join(this_dir, 'keys'),
+        lua_dir=os.path.join(this_dir, 'lua'),
+        tools_dir=os.path.join(this_dir, '..', 'tools'),
+    )
+
+
+@fixtures.fixture
+def home_path():
+    '''Per-test home directory, removed when finished.'''
+    with tempfile.TemporaryDirectory(prefix='wireshark-tests-home-') as dirname:
+        yield dirname
+
+
+@fixtures.fixture
+def conf_path(home_path):
+    '''Path to the Wireshark configuration directory.'''
+    if sys.platform.startswith('win32'):
+        conf_path = os.path.join(home_path, 'Wireshark')
+    else:
+        conf_path = os.path.join(home_path, '.config', 'wireshark')
+    os.makedirs(conf_path)
+    return conf_path
+
+
+@fixtures.fixture
+def base_env(home_path):
+    """A modified environment to ensure reproducible tests. Tests can modify
+    this environment as they see fit."""
+    env = os.environ.copy()
+    env['TZ'] = 'UTC'
+    home_env = 'APPDATA' if sys.platform.startswith('win32') else 'HOME'
+    env[home_env] = home_path
+    return env
+
+
+@fixtures.fixture
+def test_env(base_env, conf_path, request):
+    '''A process environment with a populated configuration directory.'''
+    # Populate our UAT files
+    uat_files = [
+        '80211_keys',
+        'dtlsdecrypttablefile',
+        'esp_sa',
+        'ssl_keys',
+        'c1222_decryption_table',
+        'ikev1_decryption_table',
+        'ikev2_decryption_table',
+    ]
+    for uat in uat_files:
+        # XXX stop using config
+        config.setUpUatFile(conf_path, uat)
+
+    env = base_env
+    env['WIRESHARK_RUN_FROM_BUILD_DIRECTORY'] = '1'
+    env['WIRESHARK_QUIT_AFTER_CAPTURE'] = '1'
+
+    # Remove this if test instances no longer inherit from SubprocessTestCase?
+    assert isinstance(request.instance, subprocesstest.SubprocessTestCase)
+    # Inject the test environment as default if it was not overridden.
+    request.instance.injected_test_env = env
+    return env
+
+# XXX capture: capture_interface
+# XXX nameres: setUpHostFiles() / custom_profile_path / custom_profile_name