adding tests and fix the pip install

src/tests/conftest.py

@@ -0,0 +1,12 @@
+import pytest
+from app import app
+
+# see documentation under https://flask.palletsprojects.com/en/2.0.x/testing/
+
+
+# the client here allow to use the app without running in live server
+# see https://flask.palletsprojects.com/en/2.0.x/testing/#sending-requests-with-the-test-client
+@pytest.fixture
+def client():
+    app.config['TESTING'] = True
+    yield app.test_client()