diff --git a/pyproject.toml b/pyproject.toml
index 9a68461..783d2d1 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -14,6 +14,7 @@ python = "^3.8"
 pandas = "^2.0.1"
 pyyaml = "^6.0"
 flask = "^2.3.2"
+mock = "^4.0"
 
 [tool.poetry.dev-dependencies]
 pytest = "^6.2"
diff --git a/succulent/api.py b/succulent/api.py
index db5968d..9277d6c 100644
--- a/succulent/api.py
+++ b/succulent/api.py
@@ -1,6 +1,7 @@
 from flask import Flask, jsonify, request
 from succulent.configuration import Configuration
 from succulent.processing import Processing
+from datetime import datetime
 
 class SucculentAPI:
     def __init__(self, host, port, config, format='csv'):
@@ -13,7 +14,7 @@ def __init__(self, host, port, config, format='csv'):
         self.config = conf.load_config()
 
         # Initialise processing
-        self.processing = Processing(self.config, self.format)
+        self.processing = Processing(self.config['data'], self.format)
 
         # Initialise Flask
         self.app = Flask(__name__)
@@ -31,12 +32,17 @@ def measure(self):
         try:
             # Process request
             self.processing.process(request)
+            
+            # Collect and store timestamp
+            timestamp = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
+            # You can store the timestamp in a database, file, or any other desired storage mechanism.
+            # Example: database.insert_timestamp(timestamp)
         except ValueError:
             # Invalid file type
             return jsonify({'message': f'Invalid file type: {self.format}. Supported file types: csv, json'}), 400
 
         # Send response
-        return jsonify({'message': 'Data stored'}), 200
+        return jsonify({'message': 'Data stored', 'timestamp': timestamp}), 200
 
     def start(self):
         self.app.run(host=self.host, port=self.port)
\ No newline at end of file
diff --git a/succulent/processing.py b/succulent/processing.py
index 0736e67..b5f0146 100644
--- a/succulent/processing.py
+++ b/succulent/processing.py
@@ -5,7 +5,8 @@
 class Processing:
     def __init__(self, config, format):
         self.format = format
-        self.columns = [configuration['name'] for configuration in config['data']]
+        self.columns = [configuration['name'] for configuration in config]
+        self.df = None  # Initialize df attribute
     
     def parameters(self):
         parameters = [f'{column}=' for column in self.columns]
@@ -24,18 +25,18 @@ def process(self, req):
         # Load existing data
         if os.path.exists(path):
             if self.format == 'csv':
-                df = pd.read_csv(path, sep=',')
+                self.df = pd.read_csv(path, sep=',')
             elif self.format == 'json':
-                df = pd.read_json(path, orient='records')
+                self.df = pd.read_json(path, orient='records')
             elif self.format == 'sqlite':
                 conn = sqlite3.connect(path)
-                df = pd.read_sql_query("SELECT * FROM data", conn)
+                self.df = pd.read_sql_query("SELECT * FROM data", conn)
                 conn.close()
             else:
                 raise ValueError(f'Invalid file type: {self.format}')
         # Initialise new data
         else:
-            df = pd.DataFrame(columns=self.columns)
+            self.df = pd.DataFrame(columns=self.columns)
 
         # Parse data from request
         data = {}
@@ -48,22 +49,22 @@ def process(self, req):
         else:
             for column in self.columns:
                 try: 
-                    data[column] = req.args.get(column)
+                    data[column] = str(req.args.get(column, default=''))
                 except:
-                    data[column] = None
+                    data[column] = ''
         data = pd.Series(data, index=self.columns)
 
         # Merge data
-        df = pd.concat([df, data.to_frame().T], ignore_index=True)
+        self.df = pd.concat([self.df, data.to_frame().T], ignore_index=True)
 
         # Store data to device
         if self.format == 'csv':
-            df.to_csv(output_path, sep=',', index=False)
+            self.df.to_csv(output_path, sep=',', index=False)
         elif self.format == 'json':
-            df.to_json(output_path, orient='records', indent=4)
+            self.df.to_json(output_path, orient='records', indent=4)
         elif self.format == 'sqlite':
             conn = sqlite3.connect(output_path)
-            df.to_sql('data', conn, if_exists='replace', index=False)
+            self.df.to_sql('data', conn, if_exists='replace', index=False)
             conn.close()
         else:
-            raise ValueError(f'Invalid format: {self.format}')
\ No newline at end of file
+            raise ValueError(f'Invalid format: {self.format}')
diff --git a/tests/test_succulent.py b/tests/test_succulent.py
index 6ecb845..3a2b08a 100644
--- a/tests/test_succulent.py
+++ b/tests/test_succulent.py
@@ -1,5 +1,189 @@
+from mock import patch
+from numpy import nan
 from succulent import __version__
+import unittest
+import os
+from flask import Flask
+from flask.testing import FlaskClient
+from unittest.mock import MagicMock, Mock
+from succulent.processing import Processing
+from succulent.api import SucculentAPI
+from succulent.configuration import Configuration
+from datetime import datetime
 
+class TestProcessing(unittest.TestCase):
+    """
+    Test case for the Processing class.
+    
+    This test case focuses on testing the methods and functionality of the Processing class.
+    """
+
+    def setUp(self):
+        # Load configuration from configuration.yml
+        config_path = os.path.join(os.path.dirname(os.path.abspath(__file__)), '..', 'succulent', 'configuration.yml')
+        configuration = Configuration(config_path)
+        config = configuration.load_config()
+        self.processing = Processing(config['data'], 'csv')
+
+    def test_parameters(self):
+        """
+        Test the parameters() method of the Processing class.
+
+        This test verifies that the parameters() method returns the expected string representation of the parameters.
+        """
+        expected_parameters = 'temperature=&humidity=&light=&time=&date='
+        self.assertEqual(self.processing.parameters(), expected_parameters)
+
+    def test_process_json(self):
+        # Mock the request object
+        request = MagicMock()
+        request.is_json = True
+        request.json = {
+            'temperature': '25',
+            'humidity': '50',
+            'light': 'high',
+            'time': '10:30',
+            'date': '2022-01-01'
+        }
+
+        # Process the request
+        self.processing.process(request)
+
+        # Verify the data is merged correctly
+        expected_data = [
+            {
+                'temperature': 25,
+                'humidity': 50,
+                'light': 'high',
+                'time': '10:30',
+                'date': '2022-01-01'
+            },
+            {
+                'temperature': '25',
+                'humidity': '50',
+                'light': 'high',
+                'time': '10:30',
+                'date': '2022-01-01'
+            }
+        ]
+        actual_data = self.processing.df.to_dict(orient='records')
+        print(actual_data)
+        print(expected_data)
+        self.assertEqual(actual_data, expected_data)
+
+    def test_process_args(self):
+        """
+        Test the process() method of the Processing class with query string arguments.
+
+        This test ensures that the process() method correctly merges the query string arguments with the existing DataFrame.
+        """
+        # Mock the request object
+        request = MagicMock()
+        request.is_json = False
+        request.args.get.side_effect = ["25", "50", "high", "10:30", "2022-01-01"]
+
+        # Process the request
+        self.processing.process(request)
+
+        # Verify the data is merged correctly
+        expected_data = [
+            {'temperature': '25', 'humidity': '50', 'light': 'high', 'time': '10:30', 'date': '2022-01-01'}
+        ]
+        self.assertEqual(self.processing.df.to_dict(orient='records'), expected_data)
+
+class TestSucculentAPI(unittest.TestCase):
+    """
+    Test case for the SucculentAPI class.
+    
+    This test case focuses on testing the methods and functionality of the SucculentAPI class.
+    """
+
+    def setUp(self):
+        # Create an instance of the SucculentAPI class for testing
+        self.app = Flask(__name__)
+        self.app_context = self.app.app_context()
+        self.app_context.push()
+        self.client = self.app.test_client()
+
+        config_path = os.path.join(os.path.dirname(os.path.abspath(__file__)), '..', 'succulent', 'configuration.yml')
+        self.api = SucculentAPI(host='0.0.0.0', port=8080, config=config_path, format='csv')
+
+    def test_version(self):
+        """
+        Test the version of the SucculentAPI.
+        """
+        expected_version = "0.1.1"
+        self.assertEqual(__version__, expected_version)
+
+    def test_url(self):
+        """
+        Test the URL generation of the SucculentAPI.
+        """
+        # Make a request to the URL endpoint
+        with self.api.app.test_client() as client:
+            response = client.get('/measure')
+            data = response.get_json()
+
+            # Verify the URL in the response
+            expected_url = '0.0.0.0:8080/measure?temperature=&humidity=&light=&time=&date='
+            self.assertEqual(data['url'], expected_url)
+
+    def test_measure(self):
+        # Create a mock request object
+        mock_request = Mock()
+        mock_request.is_json = True
+        mock_request.json = {
+            'temperature': 25.0,
+            'humidity': 60.0,
+            'light': 'high',
+            'time': '10:30 AM',
+            'date': '2023-05-21'
+        }
+
+        # Call the measure endpoint
+        response = self.api.app.test_client().post('/measure', json=mock_request.json)
+
+        # Assert the response and timestamp
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.json['message'], 'Data stored')
+        # Compare the timestamp with the current time
+        current_time = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
+        self.assertEqual(response.json['timestamp'], current_time)
+
+class TestConfiguration(unittest.TestCase):
+    """
+    Test case for the Configuration class.
+
+    This test case focuses on testing the methods and functionality of the Configuration class.
+    """
+
+    def setUp(self):
+        # Get the path to the configuration.yml file
+        config_path = os.path.join(os.path.dirname(os.path.abspath(__file__)), '..', 'succulent', 'configuration.yml')
+        self.configuration = Configuration(config_path)
+
+    def test_load_config(self):
+        """
+        Test the load_config() method of the Configuration class.
+
+        This test verifies that the load_config() method correctly loads the configuration from the configuration.yml file.
+        """
+        # Load the configuration from the file
+        config = self.configuration.load_config()
+
+        # Verify the loaded configuration
+        expected_config = {
+            'data': [
+                {'name': 'temperature'},
+                {'name': 'humidity'},
+                {'name': 'light'},
+                {'name': 'time'},
+                {'name': 'date'}
+            ]
+        }
+        self.assertEqual(config, expected_config)
+
+
+if __name__ == '__main__':
+    unittest.main()
 
-def test_version():
-    assert __version__ == '0.1.1'