vscode-python/python_files/tests/test_python_server.py at main · aitorciki/vscode-python · GitHub

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# Licensed under the MIT License.

"""Tests for python_server.py, specifically EOF handling to prevent infinite loops."""

import io

from unittest import mock

import pytest

class TestGetHeaders:

"""Tests for the get_headers function."""

def test_get_headers_normal(self):

"""Test get_headers with valid headers."""

# Arrange: Import the module

import python_server

# Create a mock stdin with valid headers

mock_input = b"Content-Length: 100\r\nContent-Type: application/json\r\n\r\n"

mock_stdin = io.BytesIO(mock_input)

# Act

with mock.patch.object(python_server, "STDIN", mock.Mock(buffer=mock_stdin)):

headers = python_server.get_headers()

# Assert

assert headers == {"Content-Length": "100", "Content-Type": "application/json"}

def test_get_headers_eof_raises_error(self):

"""Test that get_headers raises EOFError when stdin is closed (EOF)."""

# Arrange: Import the module

import python_server

# Create a mock stdin that returns empty bytes (EOF)

mock_stdin = io.BytesIO(b"")

# Act & Assert

with mock.patch.object(python_server, "STDIN", mock.Mock(buffer=mock_stdin)), pytest.raises(

EOFError, match="EOF reached while reading headers"

python_server.get_headers()

def test_get_headers_eof_mid_headers_raises_error(self):

"""Test that get_headers raises EOFError when EOF occurs mid-headers."""

# Arrange: Import the module

import python_server

# Create a mock stdin with partial headers then EOF

mock_input = b"Content-Length: 100\r\n" # No terminating empty line

mock_stdin = io.BytesIO(mock_input)

# Act & Assert

with mock.patch.object(python_server, "STDIN", mock.Mock(buffer=mock_stdin)), pytest.raises(

EOFError, match="EOF reached while reading headers"

python_server.get_headers()

def test_get_headers_empty_line_terminates(self):

"""Test that an empty line (not EOF) properly terminates header reading."""

# Arrange: Import the module

import python_server

# Create a mock stdin with headers followed by empty line

mock_input = b"Content-Length: 50\r\n\r\nsome body content"

mock_stdin = io.BytesIO(mock_input)

# Act

with mock.patch.object(python_server, "STDIN", mock.Mock(buffer=mock_stdin)):

headers = python_server.get_headers()

# Assert

assert headers == {"Content-Length": "50"}

class TestEOFHandling:

"""Tests for EOF handling in various functions that use get_headers."""

def test_custom_input_exits_on_eof(self):

"""Test that custom_input exits gracefully on EOF."""

# Arrange: Import the module

import python_server

# Create a mock stdin that returns empty bytes (EOF)

mock_stdin = io.BytesIO(b"")

mock_stdout = io.BytesIO()

# Act & Assert

with mock.patch.object(

python_server, "STDIN", mock.Mock(buffer=mock_stdin)

), mock.patch.object(python_server, "STDOUT", mock.Mock(buffer=mock_stdout)), pytest.raises(

SystemExit

) as exc_info:

python_server.custom_input("prompt> ")

# Should exit with code 0 (graceful exit)

assert exc_info.value.code == 0

def test_handle_response_exits_on_eof(self):

"""Test that handle_response exits gracefully on EOF."""

# Arrange: Import the module

import python_server

# Create a mock stdin that returns empty bytes (EOF)

mock_stdin = io.BytesIO(b"")

# Act & Assert

with mock.patch.object(python_server, "STDIN", mock.Mock(buffer=mock_stdin)), pytest.raises(

SystemExit

) as exc_info:

python_server.handle_response("test-request-id")

# Should exit with code 0 (graceful exit)

assert exc_info.value.code == 0

class TestMainLoopEOFHandling:

"""Tests that simulate the main loop EOF scenario."""

def test_main_loop_exits_on_eof(self):

"""Test that the main loop pattern exits gracefully on EOF.

This test verifies the fix for GitHub issue #25620 where the server

would spin at 100% CPU instead of exiting when VS Code closes.

"""

# Arrange: Import the module

import python_server

# Create a mock stdin that returns empty bytes (EOF)

mock_stdin = io.BytesIO(b"")

# Simulate what happens in the main loop

with mock.patch.object(python_server, "STDIN", mock.Mock(buffer=mock_stdin)):

try:

python_server.get_headers()

# If we get here without raising EOFError, the fix isn't working

pytest.fail("Expected EOFError to be raised on EOF")

except EOFError:

# This is the expected behavior - the fix is working

pass

def test_readline_eof_vs_empty_line(self):

"""Test that we correctly distinguish between EOF and empty line.

EOF: readline() returns b'' (empty bytes)

Empty line: readline() returns b'\\r\\n' or b'\\n' (newline bytes)

"""

# Test EOF case

eof_stream = io.BytesIO(b"")

result = eof_stream.readline()

assert result == b"", "EOF should return empty bytes"

# Test empty line case

empty_line_stream = io.BytesIO(b"\r\n")

result = empty_line_stream.readline()

assert result == b"\r\n", "Empty line should return newline bytes"

# Test empty line with just newline

empty_line_stream2 = io.BytesIO(b"\n")

result = empty_line_stream2.readline()

assert result == b"\n", "Empty line should return newline bytes"

vscode-python/python_files/tests/test_python_server.py at main · aitorciki/vscode-python · GitHub

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