fix: use StringIO instead of BytesIO with StreamWriter

samcli/commands/local/cli_common/invoke_context.py

@@ -7,7 +7,7 @@
 import os
 from enum import Enum
 from pathlib import Path
-from typing import IO, Any, Dict, List, Optional, Tuple, Type, cast
+from typing import Any, Dict, List, Optional, TextIO, Tuple, Type, cast
 
 from samcli.commands._utils.template import TemplateFailedParsingException, TemplateNotFoundException
 from samcli.commands.exceptions import ContainersInitializationException
@@ -195,7 +195,7 @@ def __init__(
         self._stacks: List[Stack] = None  # type: ignore
         self._env_vars_value: Optional[Dict] = None
         self._container_env_vars_value: Optional[Dict] = None
-        self._log_file_handle: Optional[IO] = None
+        self._log_file_handle: Optional[TextIO] = None
         self._debug_context: Optional[DebugContext] = None
         self._layers_downloader: Optional[LayerDownloader] = None
         self._container_manager: Optional[ContainerManager] = None
@@ -487,7 +487,7 @@ def _get_env_vars_value(filename: Optional[str]) -> Optional[Dict]:
             ) from ex
 
     @staticmethod
-    def _setup_log_file(log_file: Optional[str]) -> Optional[IO]:
+    def _setup_log_file(log_file: Optional[str]) -> Optional[TextIO]:
         """
         Open a log file if necessary and return the file handle. This will create a file if it does not exist
 
@@ -497,7 +497,7 @@ def _setup_log_file(log_file: Optional[str]) -> Optional[IO]:
         if not log_file:
             return None
 
-        return open(log_file, "wb")
+        return open(log_file, "w")
 
     @staticmethod
     def _get_debug_context(

samcli/lib/package/ecr_uploader.py

@@ -2,8 +2,8 @@
 Client for uploading packaged artifacts to ecr
 """
 import base64
-import io
 import logging
+from io import StringIO
 from typing import Dict
 
 import botocore
@@ -94,7 +94,7 @@ def upload(self, image, resource_name):
             else:
                 # we need to wait till the image got pushed to ecr, without this workaround sam sync for template
                 # contains image always fail, because the provided ecr uri is not exist.
-                _log_streamer = LogStreamer(stream=StreamWriter(stream=io.BytesIO(), auto_flush=True))
+                _log_streamer = LogStreamer(stream=StreamWriter(stream=StringIO(), auto_flush=True))
                 _log_streamer.stream_progress(push_logs)
 
         except (BuildError, APIError, LogStreamError) as ex:

samcli/lib/utils/stream_writer.py

@@ -1,11 +1,11 @@
 """
 This class acts like a wrapper around output streams to provide any flexibility with output we need
 """
-from typing import Union
+from typing import TextIO, Union
 
 
 class StreamWriter:
-    def __init__(self, stream, auto_flush: bool = False):
+    def __init__(self, stream: TextIO, auto_flush: bool = False):
         """
         Instatiates new StreamWriter to the specified stream
 
@@ -20,7 +20,7 @@ def __init__(self, stream, auto_flush: bool = False):
         self._auto_flush = auto_flush
 
     @property
-    def stream(self):
+    def stream(self) -> TextIO:
         return self._stream
 
     def write_bytes(self, output: Union[bytes, bytearray]):
@@ -30,7 +30,7 @@ def write_bytes(self, output: Union[bytes, bytearray]):
         Parameters
         ----------
         output bytes-like object
-            Bytes to write
+            Bytes to write into buffer
         """
         self._stream.buffer.write(output)
 
@@ -43,8 +43,8 @@ def write_str(self, output: str):
 
         Parameters
         ----------
-        output bytes-like object
-            Bytes to write
+        output string object
+            String to write
         """
         self._stream.write(output)
 

samcli/local/apigw/local_apigw_service.py

@@ -4,7 +4,7 @@
 import json
 import logging
 from datetime import datetime
-from io import BytesIO
+from io import StringIO
 from time import time
 from typing import Any, Dict, List, Optional
 
@@ -605,7 +605,7 @@ def _invoke_lambda_function(self, lambda_function_name: str, event: dict) -> str
         str
             A string containing the output from the Lambda function
         """
-        with BytesIO() as stdout:
+        with StringIO() as stdout:
             event_str = json.dumps(event, sort_keys=True)
             stdout_writer = StreamWriter(stdout, auto_flush=True)
 

samcli/local/lambda_service/local_lambda_invoke_service.py

@@ -162,7 +162,7 @@ def _invoke_request_handler(self, function_name):
 
         request_data = request_data.decode("utf-8")
 
-        stdout_stream = io.BytesIO()
+        stdout_stream = io.StringIO()
         stdout_stream_writer = StreamWriter(stdout_stream, auto_flush=True)
 
         try:

samcli/local/services/base_local_service.py

@@ -82,7 +82,7 @@ def service_response(body, headers, status_code):
 
 class LambdaOutputParser:
     @staticmethod
-    def get_lambda_output(stdout_stream: io.BytesIO) -> Tuple[str, bool]:
+    def get_lambda_output(stdout_stream: io.StringIO) -> Tuple[str, bool]:
         """
         This method will extract read the given stream and return the response from Lambda function separated out
         from any log statements it might have outputted. Logs end up in the stdout stream if the Lambda function
@@ -100,7 +100,7 @@ def get_lambda_output(stdout_stream: io.BytesIO) -> Tuple[str, bool]:
         bool
             If the response is an error/exception from the container
         """
-        lambda_response = stdout_stream.getvalue().decode("utf-8")
+        lambda_response = stdout_stream.getvalue()
 
         # When the Lambda Function returns an Error/Exception, the output is added to the stdout of the container. From
         # our perspective, the container returned some value, which is not always true. Since the output is the only

tests/unit/commands/local/cli_common/test_invoke_context.py

@@ -1106,7 +1106,7 @@ def test_must_open_file_for_writing(self):
         with patch("samcli.commands.local.cli_common.invoke_context.open", m):
             InvokeContext._setup_log_file(filename)
 
-        m.assert_called_with(filename, "wb")
+        m.assert_called_with(filename, "w")
 
 
 class TestInvokeContext_get_debug_context(TestCase):

tests/unit/local/services/test_base_local_service.py

@@ -66,17 +66,17 @@ def test_create_returns_not_implemented(self):
 class TestLambdaOutputParser(TestCase):
     @parameterized.expand(
         [
-            param("with mixed data and json response", b'data\n{"a": "b"}', 'data\n{"a": "b"}'),
-            param("with response as string", b"response", "response"),
-            param("with json response only", b'{"a": "b"}', '{"a": "b"}'),
-            param("with one new line and json", b'\n{"a": "b"}', '\n{"a": "b"}'),
-            param("with response only as string", b"this is the response line", "this is the response line"),
-            param("with whitespaces", b'data\n{"a": "b"}  \n\n\n', 'data\n{"a": "b"}  \n\n\n'),
-            param("with empty data", b"", ""),
-            param("with just new lines", b"\n\n", "\n\n"),
+            param("with mixed data and json response", 'data\n{"a": "b"}', 'data\n{"a": "b"}'),
+            param("with response as string", "response", "response"),
+            param("with json response only", '{"a": "b"}', '{"a": "b"}'),
+            param("with one new line and json", '\n{"a": "b"}', '\n{"a": "b"}'),
+            param("with response only as string", "this is the response line", "this is the response line"),
+            param("with whitespaces", 'data\n{"a": "b"}  \n\n\n', 'data\n{"a": "b"}  \n\n\n'),
+            param("with empty data", "", ""),
+            param("with just new lines", "\n\n", "\n\n"),
             param(
                 "with whitespaces",
-                b"\n   \n   \n",
+                "\n   \n   \n",
                 "\n   \n   \n",
             ),
         ]