selftests: add common method for checking presence of Python modules

There are at least two places in which the same functionality is
present.  Let's make it a single utility function instead.
Signed-off-by: NCleber Rosa <crosa@redhat.com>

selftests/__init__.py

 import os
+import pkg_resources
 import sys
 import unittest
 
@@ -33,3 +34,19 @@ def recent_mock():
     elif sys.version_info[0] == 3:
         return sys.version_info[1] >= 6
     return True
+
+
+def python_module_available(module_name):
+    '''
+    Checks if a given Python module is available
+
+    :param module_name: the name of the module
+    :type module_name: str
+    :returns: if the Python module is available in the system
+    :rtype: bool
+    '''
+    try:
+        pkg_resources.require(module_name)
+        return True
+    except pkg_resources.DistributionNotFound:
+        return False

selftests/functional/test_basic.py

@@ -12,7 +12,6 @@ import xml.dom.minidom
 import zipfile
 import unittest
 import psutil
-import pkg_resources
 
 try:
     from io import BytesIO
@@ -35,7 +34,7 @@ from avocado.utils import process
 from avocado.utils import script
 from avocado.utils import path as utils_path
 
-from .. import AVOCADO, BASEDIR
+from .. import AVOCADO, BASEDIR, python_module_available
 
 
 LOCAL_IMPORT_TEST_CONTENTS = '''
@@ -145,14 +144,6 @@ READ_BINARY = probe_binary('read')
 SLEEP_BINARY = probe_binary('sleep')
 
 
-def html_capable():
-    try:
-        pkg_resources.require('avocado-framework-plugin-result-html')
-        return True
-    except pkg_resources.DistributionNotFound:
-        return False
-
-
 class RunnerOperationTest(unittest.TestCase):
 
     def setUp(self):
@@ -782,7 +773,7 @@ class RunnerSimpleTest(unittest.TestCase):
                                                     "sysinfo", "pre",
                                                     "echo \'________\'")))
 
-        if html_capable():
+        if python_module_available('avocado-framework-plugin-result-html'):
             with open(os.path.join(self.tmpdir, "latest",
                                    "results.html")) as html_res:
                 html_results = html_res.read()
@@ -1156,7 +1147,7 @@ class PluginsTest(AbsPluginsTest, unittest.TestCase):
 
         result_plugins = ["json", "xunit", "zip_archive"]
         result_outputs = ["results.json", "results.xml"]
-        if html_capable():
+        if python_module_available('avocado-framework-plugin-result-html'):
             result_plugins.append("html")
             result_outputs.append("results.html")
 

selftests/run

@@ -5,26 +5,19 @@ __author__ = 'Lucas Meneghel Rodrigues <lmr@redhat.com>'
 
 import gc
 import os
-import pkg_resources
 import subprocess
 import sys
 import unittest
 
 from avocado.core import data_dir
 
+from selftests import python_module_available
+
 
 CHECK_TMP_DIRS = os.path.abspath(os.path.join(os.path.dirname(__file__),
                                               "check_tmp_dirs"))
 
 
-def plugin_available(plugin_name):
-    try:
-        pkg_resources.require(plugin_name)
-        return True
-    except pkg_resources.DistributionNotFound:
-        return False
-
-
 def test_suite():
     suite = unittest.TestSuite()
     loader = unittest.TestLoader()
@@ -44,7 +37,7 @@ def test_suite():
                ('avocado-framework-plugin-result-html',
                 'html'))
     for plugin_name, plugin_dir in plugins:
-        if plugin_available(plugin_name):
+        if python_module_available(plugin_name):
             path = os.path.join(basedir, 'optional_plugins',
                                 plugin_dir, 'tests')
             suite.addTests(loader.discover(start_dir=path, top_level_dir=path))