Add docstrings

Author: fabaff

tests/test_main.py

@@ -8,15 +8,18 @@
 
 
 def test_app1():
+    """Test if the app raises an error when the access key is not provided."""
     result = runner.invoke(app, ["--access_key"], input="123456\n")
     assert result.exit_code == 2
 
 
 def test_app2():
+    """Test if the app raises an error when the secret key is not provided."""
     result = runner.invoke(app, ["--secret_key"], input=None)
     assert result.exit_code == 2
 
 
 def test_app3():
+    """Test if the app raises an error when the host URL is not provided."""
     result = runner.invoke(app, ["--host"], input="https://localhost:8834\n")
     assert result.exit_code == 2