[mod] move searx/testing.py to the tests directory

move robot tests to tests.robot
manage calls "python -m tests.robot"

tests/__init__.py

@@ -1,5 +1,47 @@
 import os
 
+import aiounittest
+
 os.environ['SEARX_DEBUG'] = '1'
 os.environ['SEARX_DISABLE_ETC_SETTINGS'] = '1'
 os.environ.pop('SEARX_SETTINGS_PATH', None)
+
+
+class SearxTestLayer:
+    """Base layer for non-robot tests."""
+
+    __name__ = 'SearxTestLayer'
+
+    @classmethod
+    def setUp(cls):
+        pass
+
+    @classmethod
+    def tearDown(cls):
+        pass
+
+    @classmethod
+    def testSetUp(cls):
+        pass
+
+    @classmethod
+    def testTearDown(cls):
+        pass
+
+
+class SearxTestCase(aiounittest.AsyncTestCase):
+    """Base test case for non-robot tests."""
+
+    layer = SearxTestLayer
+
+    def setattr4test(self, obj, attr, value):
+        """
+        setattr(obj, attr, value)
+        but reset to the previous value in the cleanup.
+        """
+        previous_value = getattr(obj, attr)
+
+        def cleanup_patch():
+            setattr(obj, attr, previous_value)
+        self.addCleanup(cleanup_patch)
+        setattr(obj, attr, value)