Added pytest for testing, Added pytest and loguru packages to nix shell

shell.nix

@@ -3,17 +3,23 @@
 
 with pkgs;
 pkgs.mkShell {
-    nativeBuildInputs = [
-        inlyne # markdown viewer
+  nativeBuildInputs = [
+    inlyne # markdown viewer
 
-        # Python development environment
-        (python3.withPackages(ps: with ps; [
-            # For SDK configuration
-            python-dotenv
+    # Python development environment
+    (python3.withPackages(ps: with ps; [
+      # For SDK configuration
+      python-dotenv
 
-            # HTTP client
-            requests
-        ]))
-    ];
+      # Logging
+      loguru
+
+      # HTTP client
+      requests
+
+      # Testing
+      pytest
+    ]))
+  ];
 }
 

tests/conftest.py

@@ -0,0 +1,14 @@
+# Library imports
+import pytest
+
+####
+# Global fixtures
+####
+
+# App client for testing
+@pytest.fixture(scope='module')
+def client():
+    app = create_app(config_class='tests/testing_config.py')
+    with app.app_context():
+        yield app
+