make --alternate-language cli argument take precedence over detected language

tests/samples/output/test_help_contents

@@ -36,8 +36,8 @@ optional arguments:
                         optional alternate project name; auto-discovered
                         project takes priority
   --alternate-language ALTERNATE_LANGUAGE
-                        optional alternate language name; auto-detected
-                        languagetakes priority
+                        optional alternate language name; if valid, takes
+                        priority over auto-detected language
   --hostname HOSTNAME   hostname of current machine.
   --disableoffline      disables offline time logging instead of queuing
                         logged time

tests/test_dependencies.py

@@ -836,3 +836,67 @@ class DependenciesTestCase(utils.TestCase):
             self.assertListsEqual(dependencies, expected_dependencies)
             self.assertEquals(stats, json.loads(self.patched['wakatime.offlinequeue.Queue.push'].call_args[0][1]))
             self.patched['wakatime.offlinequeue.Queue.pop'].assert_not_called()
+
+    def test_dependencies_still_detected_when_alternate_language_used(self):
+        response = Response()
+        response.status_code = 0
+        self.patched['wakatime.packages.requests.adapters.HTTPAdapter.send'].return_value = response
+
+        with utils.TemporaryDirectory() as tempdir:
+            entity = 'tests/samples/codefiles/python.py'
+            shutil.copy(entity, os.path.join(tempdir, 'python.py'))
+            entity = os.path.realpath(os.path.join(tempdir, 'python.py'))
+
+            now = u(int(time.time()))
+            config = 'tests/samples/configs/good_config.cfg'
+
+            args = ['--file', entity, '--config', config, '--time', now, '--alternate-language', 'PYTHON']
+
+            with utils.mock.patch('wakatime.stats.smart_guess_lexer') as mock_guess_lexer:
+                mock_guess_lexer.return_value = None
+
+                retval = execute(args)
+
+                self.assertEquals(retval, 102)
+                self.assertEquals(sys.stdout.getvalue(), '')
+                self.assertEquals(sys.stderr.getvalue(), '')
+
+                self.patched['wakatime.session_cache.SessionCache.get'].assert_called_once_with()
+                self.patched['wakatime.session_cache.SessionCache.delete'].assert_called_once_with()
+                self.patched['wakatime.session_cache.SessionCache.save'].assert_not_called()
+
+                heartbeat = {
+                    'language': u('Python'),
+                    'lines': 37,
+                    'entity': os.path.realpath(entity),
+                    'project': u(os.path.basename(os.path.realpath('.'))),
+                    'dependencies': ANY,
+                    'time': float(now),
+                    'type': 'file',
+                }
+                stats = {
+                    u('cursorpos'): None,
+                    u('dependencies'): ANY,
+                    u('language'): u('Python'),
+                    u('lineno'): None,
+                    u('lines'): 37,
+                }
+                expected_dependencies = [
+                    'app',
+                    'django',
+                    'flask',
+                    'jinja',
+                    'mock',
+                    'pygments',
+                    'simplejson',
+                    'sqlalchemy',
+                    'unittest',
+                ]
+
+                self.patched['wakatime.offlinequeue.Queue.push'].assert_called_once_with(ANY, ANY, None)
+                for key, val in self.patched['wakatime.offlinequeue.Queue.push'].call_args[0][0].items():
+                    self.assertEquals(heartbeat[key], val)
+                dependencies = self.patched['wakatime.offlinequeue.Queue.push'].call_args[0][0]['dependencies']
+                self.assertListsEqual(dependencies, expected_dependencies)
+                self.assertEquals(stats, json.loads(self.patched['wakatime.offlinequeue.Queue.push'].call_args[0][1]))
+                self.patched['wakatime.offlinequeue.Queue.pop'].assert_not_called()

tests/test_languages.py

@@ -104,7 +104,7 @@ class LanguagesTestCase(utils.TestCase):
         language = u('Python')
         self.assertEqual(self.patched['wakatime.offlinequeue.Queue.push'].call_args[0][0].get('language'), language)
 
-    def test_alternate_language_not_used_when_guessed(self):
+    def test_alternate_language_takes_priority_over_detected_language(self):
         response = Response()
         response.status_code = 500
         self.patched['wakatime.packages.requests.adapters.HTTPAdapter.send'].return_value = response
@@ -112,12 +112,12 @@ class LanguagesTestCase(utils.TestCase):
         now = u(int(time.time()))
         config = 'tests/samples/configs/good_config.cfg'
         entity = 'tests/samples/codefiles/python.py'
-        args = ['--file', entity, '--config', config, '--time', now, '--alternate-language', 'java']
+        args = ['--file', entity, '--config', config, '--time', now, '--alternate-language', 'JAVA']
 
         retval = execute(args)
         self.assertEquals(retval, 102)
 
-        language = u('Python')
+        language = u('Java')
         self.assertEqual(self.patched['wakatime.offlinequeue.Queue.push'].call_args[0][0].get('language'), language)
 
     def test_alternate_language_is_used_when_not_guessed(self):

wakatime/arguments.py

@@ -82,8 +82,8 @@ def parseArguments():
             help='optional alternate project name; auto-discovered project '+
                  'takes priority')
     parser.add_argument('--alternate-language', dest='alternate_language',
-            help='optional alternate language name; auto-detected language'+
-                 'takes priority')
+            help='optional alternate language name; if valid, takes priority '+
+                 'over auto-detected language')
     parser.add_argument('--hostname', dest='hostname', help='hostname of '+
                         'current machine.')
     parser.add_argument('--disableoffline', dest='offline',

wakatime/stats.py

@@ -18,6 +18,7 @@ from .dependencies import DependencyParser
 
 from .packages.pygments.lexers import (
     ClassNotFound,
+    find_lexer_class,
     get_lexer_by_name,
     guess_lexer_for_filename,
 )
@@ -43,11 +44,15 @@ def get_file_stats(file_name, entity_type='file', lineno=None, cursorpos=None,
             'cursorpos': cursorpos,
         }
     else:
-        language, lexer = guess_language(file_name)
+        language = standardize_language(alternate_language, plugin)
+        lexer = get_lexer(language)
+
+        if not language:
+            language, lexer = guess_language(file_name)
+
         parser = DependencyParser(file_name, lexer)
         dependencies = parser.parse()
-        if language is None and alternate_language:
-            language = standardize_language(alternate_language, plugin)
+
         stats = {
             'language': language,
             'dependencies': dependencies,
@@ -58,6 +63,19 @@ def get_file_stats(file_name, entity_type='file', lineno=None, cursorpos=None,
     return stats
 
 
+def get_lexer(language):
+    """Return a Pygments Lexer object for the given language string."""
+
+    if not language:
+        return None
+
+    lexer_cls = find_lexer_class(language)
+    if lexer_cls:
+        return lexer_cls()
+
+    return None
+
+
 def guess_language(file_name):
     """Guess lexer and language for a file.
 
@@ -188,6 +206,9 @@ def number_lines_in_file(file_name):
 def standardize_language(language, plugin):
     """Maps a string to the equivalent Pygments language."""
 
+    if not language:
+        return None
+
     # standardize language for this plugin
     if plugin:
         plugin = plugin.split(' ')[-1].split('/')[0].split('-')[0]