avocado/core/loader.py: implement ordered test discovery

The order in which test classes and methods are found is relevant
to the loader result.  Currently, this ordering is not dependable
as the loader findings are stored on a regular dictionary.

This change makes the ordering dependable, and so happens to also
make the test pass on a Python 3 environment.
Signed-off-by: NCleber Rosa <crosa@redhat.com>

avocado/core/loader.py

@@ -18,6 +18,7 @@ Test loader module.
 """
 
 import ast
+import collections
 import imp
 import inspect
 import os
@@ -642,7 +643,7 @@ class FileLoader(TestLoader):
         # The name used, in case of 'import avocado as avocadolib'
         mod_import_name = None
         # The resulting test classes
-        result = {}
+        result = collections.OrderedDict()
         disabled = set()
 
         if os.path.isdir(path):

selftests/unit/test_loader.py

@@ -465,16 +465,16 @@ class LoaderTest(unittest.TestCase):
         with avocado_test_tags as test:
             test_suite = self.loader.discover(test.path, loader.ALL)
             self.assertEqual(len(test_suite), 5)
-            self.assertEqual(test_suite[0][0], 'SafeTest')
-            self.assertEqual(test_suite[0][1]['methodName'], 'test_safe')
+            self.assertEqual(test_suite[0][0], 'FastTest')
+            self.assertEqual(test_suite[0][1]['methodName'], 'test_fast')
             self.assertEqual(test_suite[1][0], 'FastTest')
-            self.assertEqual(test_suite[1][1]['methodName'], 'test_fast')
-            self.assertEqual(test_suite[2][0], 'FastTest')
-            self.assertEqual(test_suite[2][1]['methodName'], 'test_fast_other')
+            self.assertEqual(test_suite[1][1]['methodName'], 'test_fast_other')
+            self.assertEqual(test_suite[2][0], 'SlowTest')
+            self.assertEqual(test_suite[2][1]['methodName'], 'test_slow')
             self.assertEqual(test_suite[3][0], 'SlowUnsafeTest')
             self.assertEqual(test_suite[3][1]['methodName'], 'test_slow_unsafe')
-            self.assertEqual(test_suite[4][0], 'SlowTest')
-            self.assertEqual(test_suite[4][1]['methodName'], 'test_slow')
+            self.assertEqual(test_suite[4][0], 'SafeTest')
+            self.assertEqual(test_suite[4][1]['methodName'], 'test_safe')
             filtered = loader.filter_test_tags(test_suite, ['fast,net'])
             self.assertEqual(len(filtered), 2)
             self.assertEqual(filtered[0][0], 'FastTest')
@@ -499,10 +499,10 @@ class LoaderTest(unittest.TestCase):
             self.assertEqual(filtered[0][1]['methodName'], 'test_fast')
             self.assertEqual(filtered[1][0], 'FastTest')
             self.assertEqual(filtered[1][1]['methodName'], 'test_fast_other')
-            self.assertEqual(filtered[2][0], 'SlowUnsafeTest')
-            self.assertEqual(filtered[2][1]['methodName'], 'test_slow_unsafe')
-            self.assertEqual(filtered[3][0], 'SlowTest')
-            self.assertEqual(filtered[3][1]['methodName'], 'test_slow')
+            self.assertEqual(filtered[2][0], 'SlowTest')
+            self.assertEqual(filtered[2][1]['methodName'], 'test_slow')
+            self.assertEqual(filtered[3][0], 'SlowUnsafeTest')
+            self.assertEqual(filtered[3][1]['methodName'], 'test_slow_unsafe')
             filtered = loader.filter_test_tags(test_suite,
                                                ['-fast,-slow'])
             self.assertEqual(len(filtered), 1)