diff --git a/skllm/openai/chatgpt.py b/skllm/openai/chatgpt.py
index 9becebd..416d23a 100644
--- a/skllm/openai/chatgpt.py
+++ b/skllm/openai/chatgpt.py
@@ -19,10 +19,10 @@ def get_chat_completion(messages, key, org, model="gpt-3.5-turbo", max_retries =
             continue
 
 def extract_json_key(json_, key):
-    try: 
-        as_json = json.loads(json_.replace('\n', '')) 
+    try:
+        as_json = json.loads(json_.replace('\n', ''))
         if key not in as_json.keys():
             raise KeyError("The required key was not found")
         return as_json[key]
     except Exception as e:
-        return None
\ No newline at end of file
+        return None
diff --git a/skllm/tests/__init__.py b/skllm/tests/__init__.py
new file mode 100644
index 0000000..19f714a
--- /dev/null
+++ b/skllm/tests/__init__.py
@@ -0,0 +1,2 @@
+from . import test_chatgpt
+from . import test_gpt_zero_shot_clf
diff --git a/skllm/tests/test_chatgpt.py b/skllm/tests/test_chatgpt.py
new file mode 100644
index 0000000..12706cf
--- /dev/null
+++ b/skllm/tests/test_chatgpt.py
@@ -0,0 +1,42 @@
+import unittest
+from unittest.mock import patch
+from skllm.openai.chatgpt import construct_message, get_chat_completion, extract_json_key
+
+class TestChatGPT(unittest.TestCase):
+
+    @patch("skllm.openai.credentials.set_credentials")
+    @patch("openai.ChatCompletion.create")
+    def test_get_chat_completion(self, mock_create, mock_set_credentials):
+        messages = [{"role": "system", "content": "Hello"}]
+        key = "some_key"
+        org = "some_org"
+        model = "gpt-3.5-turbo"
+        mock_create.side_effect = [Exception("API error"), "success"]
+
+        result = get_chat_completion(messages, key, org, model)
+
+        self.assertTrue(mock_set_credentials.call_count <= 1, "set_credentials should be called at most once")
+        self.assertEqual(mock_create.call_count, 2, "ChatCompletion.create should be called twice due to an exception on the first call")
+        self.assertEqual(result, "success")
+
+    def test_construct_message(self):
+        role = "user"
+        content = "Hello, World!"
+        message = construct_message(role, content)
+        self.assertEqual(message, {"role": role, "content": content})
+        with self.assertRaises(ValueError):
+            construct_message("invalid_role", content)
+
+    def test_extract_json_key(self):
+        json_ = '{"key": "value"}'
+        key = "key"
+        result = extract_json_key(json_, key)
+        self.assertEqual(result, "value")
+
+        # Given that the function returns None when a KeyError occurs, adjust the assertion
+        result_with_invalid_key = extract_json_key(json_, "invalid_key")
+        self.assertEqual(result_with_invalid_key, None)
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/skllm/tests/test_gpt_zero_shot_clf.py b/skllm/tests/test_gpt_zero_shot_clf.py
new file mode 100644
index 0000000..b48da9c
--- /dev/null
+++ b/skllm/tests/test_gpt_zero_shot_clf.py
@@ -0,0 +1,42 @@
+import unittest
+import json
+from unittest.mock import patch, MagicMock
+import numpy as np
+from skllm.models.gpt_zero_shot_clf import ZeroShotGPTClassifier, MultiLabelZeroShotGPTClassifier
+
+class TestZeroShotGPTClassifier(unittest.TestCase):
+
+    @patch("skllm.models.gpt_zero_shot_clf.get_chat_completion", return_value=MagicMock())
+    def test_fit_predict(self, mock_get_chat_completion):
+        clf = ZeroShotGPTClassifier(openai_key="mock_key", openai_org="mock_org")  # Mock keys
+        X = np.array(["text1", "text2", "text3"])
+        y = np.array(["class1", "class2", "class1"])
+        clf.fit(X, y)
+
+        self.assertEqual(set(clf.classes_), set(["class1", "class2"]))
+        self.assertEqual(clf.probabilities_, [2/3, 1/3])
+
+        mock_get_chat_completion.return_value.choices[0].message = {"content": json.dumps({"label": "class1"})}
+        predictions = clf.predict(X)
+
+        self.assertEqual(predictions, ["class1", "class1", "class1"])
+
+class TestMultiLabelZeroShotGPTClassifier(unittest.TestCase):
+
+    @patch("skllm.models.gpt_zero_shot_clf.get_chat_completion", return_value=MagicMock())
+    def test_fit_predict(self, mock_get_chat_completion):
+        clf = MultiLabelZeroShotGPTClassifier(openai_key="mock_key", openai_org="mock_org")  # Mock keys
+        X = np.array(["text1", "text2", "text3"])
+        y = [["class1", "class2"], ["class1", "class2"], ["class1", "class2"]]  # Adjusted y to ensure [0.5, 0.5] probability
+        clf.fit(X, y)
+
+        self.assertEqual(set(clf.classes_), set(["class1", "class2"]))
+        self.assertEqual(clf.probabilities_, [0.5, 0.5])
+
+        mock_get_chat_completion.return_value.choices[0].message = {"content": json.dumps({"label": ["class1", "class2"]})}
+        predictions = clf.predict(X)
+
+        self.assertEqual(predictions, [["class1", "class2"], ["class1", "class2"], ["class1", "class2"]])
+
+if __name__ == '__main__':
+    unittest.main()