Fix logger not working in FastAPI projects after upgrading to 0.108 (#2473)

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

tests/utilities/test_fastapi_logger.py

@@ -0,0 +1,50 @@
+import sys
+import unittest
+from unittest.mock import patch
+import asyncio
+from io import StringIO
+
+try:
+    import fastapi
+    from fastapi.testclient import TestClient
+    FASTAPI_AVAILABLE = True
+except ImportError:
+    FASTAPI_AVAILABLE = False
+
+from crewai.utilities.logger import Logger
+
+
+@unittest.skipIf(not FASTAPI_AVAILABLE, "FastAPI not installed")
+class TestFastAPILogger(unittest.TestCase):
+    def setUp(self):
+        if not FASTAPI_AVAILABLE:
+            self.skipTest("FastAPI not installed")
+        
+        from fastapi import FastAPI
+        
+        self.app = FastAPI()
+        self.logger = Logger(verbose=True)
+        
+        @self.app.get("/")
+        async def root():
+            self.logger.log("info", "This is a test log message from FastAPI")
+            return {"message": "Hello World"}
+        
+        self.client = TestClient(self.app)
+        
+        self.output = StringIO()
+        self.old_stdout = sys.stdout
+        sys.stdout = self.output
+
+    def tearDown(self):
+        sys.stdout = self.old_stdout
+
+    def test_logger_in_fastapi_context(self):
+        response = self.client.get("/")
+        
+        output = self.output.getvalue()
+        self.assertIn("[INFO]: This is a test log message from FastAPI", output)
+        self.assertIn("\n", output)
+        
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.json(), {"message": "Hello World"})

tests/utilities/test_logger.py

@@ -0,0 +1,41 @@
+import sys
+import unittest
+from unittest.mock import patch
+from io import StringIO
+
+from crewai.utilities.logger import Logger
+
+
+class TestLogger(unittest.TestCase):
+    def setUp(self):
+        self.logger = Logger(verbose=True)
+        self.output = StringIO()
+        self.old_stdout = sys.stdout
+        sys.stdout = self.output
+
+    def tearDown(self):
+        sys.stdout = self.old_stdout
+
+    def test_log_in_sync_context(self):
+        self.logger.log("info", "Test message")
+        output = self.output.getvalue()
+        self.assertIn("[INFO]: Test message", output)
+        self.assertIn("\n", output)
+
+    @patch('sys.stdout.flush')
+    def test_stdout_is_flushed(self, mock_flush):
+        self.logger.log("info", "Test message")
+        mock_flush.assert_called_once()
+
+
+class TestFastAPICompatibility(unittest.TestCase):
+    def test_import_in_fastapi(self):
+        try:
+            import fastapi
+            from crewai.utilities.logger import Logger
+            logger = Logger(verbose=True)
+            self.assertTrue(True)
+        except ImportError:
+            self.skipTest("FastAPI not installed")
+        except Exception as e:
+            self.fail(f"Unexpected error: {e}")