Fix issue #2528: Restore language option in crew configuration

Co-Authored-By: Joe Moura <joao@crewai.com>

tests/crew_language_test.py

@@ -0,0 +1,40 @@
+import pytest
+from unittest.mock import patch
+
+from crewai import Crew, Agent, Process, Task
+from crewai.utilities.i18n import I18N
+
+
+def test_crew_with_language():
+    i18n = I18N(language="en")
+    
+    agent = Agent(
+        role="Test Agent",
+        goal="Test Goal",
+        backstory="Test Backstory",
+        verbose=True
+    )
+    
+    task = Task(
+        description="Test Task",
+        expected_output="Test Output",
+        agent=agent
+    )
+    
+    with patch('crewai.crew.I18N') as mock_i18n:
+        mock_i18n.return_value = i18n
+        
+        crew = Crew(
+            agents=[agent],
+            tasks=[task],
+            process=Process.sequential,
+            verbose=True,
+            language="fr"  # Use French as an example
+        )
+        
+        with patch.object(crew, '_run_sequential_process'):
+            with patch.object(crew, '_set_tasks_callbacks'):
+                with patch('crewai.agent.Agent.create_agent_executor'):
+                    crew.kickoff()
+                    
+                    mock_i18n.assert_called_with(prompt_file=None, language="fr")

tests/utilities/test_i18n.py

@@ -42,3 +42,13 @@ def test_prompt_file():
     i18n.load_prompts()
     assert isinstance(i18n.retrieve("slices", "role_playing"), str)
     assert i18n.retrieve("slices", "role_playing") == "Lorem ipsum dolor sit amet"
+
+
+def test_language_parameter():
+    i18n = I18N(language="en")
+    i18n.load_prompts()
+    assert isinstance(i18n.slice("role_playing"), str)
+
+    i18n = I18N(language="nonexistent")
+    i18n.load_prompts()
+    assert isinstance(i18n.slice("role_playing"), str)