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

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

src/crewai/utilities/printer.py

@@ -1,42 +1,44 @@
 from typing import Optional
+import sys
 
 
 class Printer:
     def print(self, content: str, color: Optional[str] = None):
+        output = content
         if color == "purple":
-            self._print_purple(content)
+            output = self._format_purple(content)
         elif color == "red":
-            self._print_red(content)
+            output = self._format_red(content)
         elif color == "bold_green":
-            self._print_bold_green(content)
+            output = self._format_bold_green(content)
         elif color == "bold_purple":
-            self._print_bold_purple(content)
+            output = self._format_bold_purple(content)
         elif color == "bold_blue":
-            self._print_bold_blue(content)
+            output = self._format_bold_blue(content)
         elif color == "yellow":
-            self._print_yellow(content)
+            output = self._format_yellow(content)
         elif color == "bold_yellow":
-            self._print_bold_yellow(content)
-        else:
-            print(content)
+            output = self._format_bold_yellow(content)
+        sys.stdout.write(f"{output}\n")
+        sys.stdout.flush()
 
-    def _print_bold_purple(self, content):
-        print("\033[1m\033[95m {}\033[00m".format(content))
+    def _format_bold_purple(self, content):
+        return "\033[1m\033[95m {}\033[00m".format(content)
 
-    def _print_bold_green(self, content):
-        print("\033[1m\033[92m {}\033[00m".format(content))
+    def _format_bold_green(self, content):
+        return "\033[1m\033[92m {}\033[00m".format(content)
 
-    def _print_purple(self, content):
-        print("\033[95m {}\033[00m".format(content))
+    def _format_purple(self, content):
+        return "\033[95m {}\033[00m".format(content)
 
-    def _print_red(self, content):
-        print("\033[91m {}\033[00m".format(content))
+    def _format_red(self, content):
+        return "\033[91m {}\033[00m".format(content)
 
-    def _print_bold_blue(self, content):
-        print("\033[1m\033[94m {}\033[00m".format(content))
+    def _format_bold_blue(self, content):
+        return "\033[1m\033[94m {}\033[00m".format(content)
 
-    def _print_yellow(self, content):
-        print("\033[93m {}\033[00m".format(content))
+    def _format_yellow(self, content):
+        return "\033[93m {}\033[00m".format(content)
 
-    def _print_bold_yellow(self, content):
-        print("\033[1m\033[93m {}\033[00m".format(content))
+    def _format_bold_yellow(self, content):
+        return "\033[1m\033[93m {}\033[00m".format(content)

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}")