Fix evaluation priority of the bootstrap settings

Closes GitLab issue #702. Thanks to Kevin Pawsey (@kevinpawsey) for
the report and the help debuging the issue.

Signed-off-by: Roberto Rosario <roberto.rosario@mayan-edms.com>

mayan/apps/smart_settings/tests/test_utils.py

@@ -0,0 +1,61 @@
+from __future__ import absolute_import, unicode_literals
+
+from mayan.apps.common.tests.base import BaseTestCase
+from mayan.apps.common.tests.mixins import EnvironmentTestCaseMixin
+
+from .literals import (
+    TEST_BOOTSTAP_SETTING_NAME, TEST_SETTING_VALUE,
+    TEST_SETTING_VALUE_OVERRIDE
+)
+from .mixins import BoostrapSettingTestMixin
+
+
+class BoostrapSettingTestCase(
+    BoostrapSettingTestMixin, EnvironmentTestCaseMixin, BaseTestCase
+):
+    def setUp(self):
+        super(BoostrapSettingTestCase, self).setUp()
+        self._register_test_boostrap_setting()
+        self._create_test_bootstrap_singleton()
+
+    def test_bootstrap_environment_overrides_config(self):
+        self._set_environment_variable(
+            name='MAYAN_{}'.format(TEST_BOOTSTAP_SETTING_NAME),
+            value=TEST_SETTING_VALUE_OVERRIDE
+        )
+
+        self._create_test_config_file(value=TEST_SETTING_VALUE)
+
+        self.assertEqual(
+            self.test_globals[TEST_BOOTSTAP_SETTING_NAME],
+            TEST_SETTING_VALUE_OVERRIDE
+        )
+
+    def test_bootstrap_config_overrides_settings(self):
+        self.test_globals[TEST_BOOTSTAP_SETTING_NAME] = TEST_SETTING_VALUE
+
+        self._create_test_config_file(value=TEST_SETTING_VALUE_OVERRIDE)
+
+        self.assertEqual(
+            self.test_globals[TEST_BOOTSTAP_SETTING_NAME],
+            TEST_SETTING_VALUE_OVERRIDE
+        )
+
+    def test_bootstrap_settings_overrides_default(self):
+        self.test_globals[
+            TEST_BOOTSTAP_SETTING_NAME
+        ] = TEST_SETTING_VALUE_OVERRIDE
+
+        self.setting_namespace.update_globals()
+
+        self.assertEqual(
+            self.test_globals[TEST_BOOTSTAP_SETTING_NAME],
+            TEST_SETTING_VALUE_OVERRIDE
+        )
+
+    def test_bootstrap_default(self):
+        self.setting_namespace.update_globals()
+
+        self.assertEqual(
+            self.test_globals[TEST_BOOTSTAP_SETTING_NAME], 'value default'
+        )