loader: Improve broken-tests-listing

Currently we provide a short mapping to notify the user why is this
test_reference not a test along with coloring it by a different color.
Let's also include a shor message to the test name to explain why is it
so to improve the user experience.
Signed-off-by: NLukáš Doktor <ldoktor@redhat.com>

avocado/core/loader.py

@@ -472,6 +472,8 @@ class FileLoader(TestLoader):
     """
 
     name = 'file'
+    __not_test_str = (": Does not look like an INSTRUMENTED test, nor is "
+                      "it executable")
 
     def __init__(self, args, extra_params):
         test_type = extra_params.pop('allowed_test_types', None)
@@ -717,7 +719,8 @@ class FileLoader(TestLoader):
                 else:
                     # Module does not have an avocado test class inside, and
                     # it's not executable. Not a Test.
-                    return make_broken(NotATest, test_path)
+                    return make_broken(NotATest,
+                                       test_path + self.__not_test_str)
 
         # Since a lot of things can happen here, the broad exception is
         # justified. The user will get it unadulterated anyway, and avocado
@@ -730,7 +733,7 @@ class FileLoader(TestLoader):
                 # execute it.
                 return self._make_test(test.SimpleTest, test_path)
             else:
-                return make_broken(NotATest, test_path)
+                return make_broken(NotATest, test_path + self.__not_test_str)
 
     @staticmethod
     def _make_test(klass, uid):
@@ -759,7 +762,8 @@ class FileLoader(TestLoader):
         test_name = test_path
         if os.path.exists(test_path):
             if os.access(test_path, os.R_OK) is False:
-                return make_broken(AccessDeniedPath, test_path)
+                return make_broken(AccessDeniedPath, test_path + ": Is not "
+                                   "readable")
             path_analyzer = path.PathInspector(test_path)
             if path_analyzer.is_python():
                 return self._make_avocado_tests(test_path, make_broken,
@@ -769,14 +773,17 @@ class FileLoader(TestLoader):
                     return self._make_test(test.SimpleTest,
                                            test_path)
                 else:
-                    return make_broken(NotATest, test_path)
+                    return make_broken(NotATest,
+                                       test_path + self.__not_test_str)
         else:
             if os.path.islink(test_path):
                 try:
                     if not os.path.isfile(os.readlink(test_path)):
-                        return make_broken(BrokenSymlink, test_path)
+                        return make_broken(BrokenSymlink, test_path + ": Is "
+                                           "a broken symlink")
                 except OSError:
-                    return make_broken(AccessDeniedPath, test_path)
+                    return make_broken(AccessDeniedPath, test_path + ": Is "
+                                       "not accessible.")
 
             # Try to resolve test ID (keep compatibility)
             test_path = os.path.join(data_dir.get_test_dir(), test_name)
@@ -793,7 +800,7 @@ class FileLoader(TestLoader):
                         return self._make_avocado_tests(test_path, make_broken,
                                                         subtests_filter,
                                                         test_name)
-        return make_broken(MissingTest, test_name)
+        return make_broken(NotATest, test_name + self.__not_test_str)
 
 
 class ExternalLoader(TestLoader):