Add Cohere LLM support (#751)

tests/llm/test_cohere.py

@@ -0,0 +1,33 @@
+import os
+import unittest
+from unittest.mock import patch
+
+from embedchain.config import BaseLlmConfig
+from embedchain.llm.cohere import CohereLlm
+
+
+class TestCohereLlm(unittest.TestCase):
+    def setUp(self):
+        os.environ["COHERE_API_KEY"] = "test_api_key"
+        self.config = BaseLlmConfig(model="gptd-instruct-tft", max_tokens=50, temperature=0.7, top_p=0.8)
+
+    def test_init_raises_value_error_without_api_key(self):
+        os.environ.pop("COHERE_API_KEY")
+        with self.assertRaises(ValueError):
+            CohereLlm()
+
+    def test_get_llm_model_answer_raises_value_error_for_system_prompt(self):
+        llm = CohereLlm(self.config)
+        llm.config.system_prompt = "system_prompt"
+        with self.assertRaises(ValueError):
+            llm.get_llm_model_answer("prompt")
+
+    @patch("embedchain.llm.cohere.CohereLlm._get_answer")
+    def test_get_llm_model_answer(self, mock_get_answer):
+        mock_get_answer.return_value = "Test answer"
+
+        llm = CohereLlm(self.config)
+        answer = llm.get_llm_model_answer("Test query")
+
+        self.assertEqual(answer, "Test answer")
+        mock_get_answer.assert_called_once()