⚡️ Speed up method InteractiveMigrationQuestioner.ask_auto_now_add_addition by 15%

[codeflash-ai]

📄 15% (0.15x) speedup for InteractiveMigrationQuestioner.ask_auto_now_add_addition in django/db/migrations/questioner.py

⏱️ Runtime : 1.50 milliseconds → 1.30 milliseconds (best of 435 runs)

📝 Explanation and details

The optimization achieves a 15% speedup by reducing I/O overhead through batched output operations:

Key optimizations:

1. Batched writes in _choice_input: Instead of 3-4 separate write() calls for the menu display, the code builds a list and joins it into a single write operation. This reduces I/O calls from ~4 to 1 per menu display.

2. Batched banner output in _ask_default: The initial instruction text (4 separate writes) is now collected in a list and output as one batched write, reducing I/O overhead.

3. Pre-computed prompt string: The default prompt format is calculated once outside the input loop rather than being conditionally formatted on each iteration.

Why this is faster:

• Each OutputWrapper.write() call has inherent overhead (method dispatch, string formatting, output flushing)
• I/O operations are typically expensive compared to string operations
• Building strings in memory with join() is more efficient than multiple separate write calls
• The line profiler shows the batched write operations (self.prompt_output.write("\n".join(buf))) take proportionally less time than the sum of individual writes in the original

Test case performance:
The optimizations show consistent 2-11% improvements across all test cases, with the best gains on simpler cases that don't involve extensive user input loops (where I/O batching has maximum impact). Complex scenarios with many invalid inputs see smaller but still meaningful improvements since the menu display overhead is reduced.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 193 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	🔘 None Found
📊 Tests Coverage	83.3%

🌀 Generated Regression Tests and Runtime

import datetime
import io
import sys

# imports
import pytest
from django.db.migrations.questioner import InteractiveMigrationQuestioner


# Minimal OutputWrapper stub for testing
class OutputWrapper:
    def __init__(self, out, ending="\n"):
        self._out = out
        self.style_func = lambda x: x
        self.ending = ending

    def write(self, msg="", style_func=None, ending=None):
        ending = self.ending if ending is None else ending
        if ending and not msg.endswith(ending):
            msg += ending
        style_func = style_func or self.style_func
        self._out.write(style_func(msg))

# Minimal timezone stub
class timezone:
    @staticmethod
    def now():
        return "timezone.now()"

# Helper context manager to patch input() for testing
class patch_input:
    def __init__(self, responses):
        self.responses = responses
        self._input_iter = iter(self.responses)
        self._orig_input = None

    def __enter__(self):
        self._orig_input = __builtins__['input']
        __builtins__['input'] = self._input
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        __builtins__['input'] = self._orig_input

    def _input(self, *args, **kwargs):
        try:
            return next(self._input_iter)
        except StopIteration:
            raise EOFError("No more input responses provided.")

# Helper context manager to capture sys.exit calls
class ExitCalled(Exception):
    def __init__(self, code):
        self.code = code

def patch_sys_exit():
    orig_exit = sys.exit
    def fake_exit(code=0):
        raise ExitCalled(code)
    sys.exit = fake_exit
    return orig_exit

def restore_sys_exit(orig_exit):
    sys.exit = orig_exit

# Helper to capture output
class OutputBuffer(io.StringIO):
    def write(self, s):
        super().write(s)

# ------------------- Unit Tests -------------------

# Basic Test Cases


def test_provide_default_timezone_now():
    """Test user selects option 1 and accepts default 'timezone.now'."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    with patch_input(["1", ""]):
        codeflash_output = q.ask_auto_now_add_addition("created", "MyModel"); result = codeflash_output # 16.4μs -> 15.0μs (9.41% faster)

def test_provide_custom_default():
    """Test user selects option 1 and provides custom default value."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    with patch_input(["1", "datetime.datetime(2020, 1, 1)"]):
        codeflash_output = q.ask_auto_now_add_addition("created", "MyModel"); result = codeflash_output # 21.2μs -> 20.4μs (4.19% faster)

def test_quit_option_exits():
    """Test user selects option 2 and sys.exit(3) is called."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    orig_exit = patch_sys_exit()
    try:
        with patch_input(["2"]):
            try:
                q.ask_auto_now_add_addition("created", "MyModel")
            except ExitCalled as e:
                pass
            else:
                pass
    finally:
        restore_sys_exit(orig_exit)

def test_invalid_choice_then_valid():
    """Test user enters invalid choice then valid choice."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    with patch_input(["0", "1", ""]):
        codeflash_output = q.ask_auto_now_add_addition("created", "MyModel"); result = codeflash_output # 17.2μs -> 16.0μs (7.37% faster)

def test_invalid_python_then_valid():
    """Test user enters invalid Python, then valid default."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    with patch_input(["1", "notavalidpython", ""]):
        codeflash_output = q.ask_auto_now_add_addition("created", "MyModel"); result = codeflash_output # 24.0μs -> 22.7μs (5.39% faster)



def test_exit_string_in_ask_default():
    """Test user types 'exit' in _ask_default and sys.exit(1) is called."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    orig_exit = patch_sys_exit()
    try:
        with patch_input(["1", "exit"]):
            try:
                q.ask_auto_now_add_addition("created", "MyModel")
            except ExitCalled as e:
                pass
            else:
                pass
    finally:
        restore_sys_exit(orig_exit)

# Edge Test Cases

def test_field_and_model_names_with_special_chars():
    """Test field/model names with unusual characters."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    with patch_input(["1", ""]):
        codeflash_output = q.ask_auto_now_add_addition("created_at$", "Model@Name"); result = codeflash_output # 23.4μs -> 21.7μs (8.02% faster)

def test_field_and_model_names_empty_string():
    """Test empty field/model names."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    with patch_input(["1", ""]):
        codeflash_output = q.ask_auto_now_add_addition("", ""); result = codeflash_output # 17.6μs -> 16.1μs (9.01% faster)

def test_default_value_is_none():
    """Test providing 'None' as the default value."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    with patch_input(["1", "None"]):
        codeflash_output = q.ask_auto_now_add_addition("created", "MyModel"); result = codeflash_output # 15.3μs -> 14.0μs (9.20% faster)

def test_large_integer_default():
    """Test providing a large integer as the default value."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    large_int = 10**18
    with patch_input(["1", str(large_int)]):
        codeflash_output = q.ask_auto_now_add_addition("created", "MyModel"); result = codeflash_output # 15.2μs -> 13.6μs (11.4% faster)

def test_multiple_invalid_choices_then_valid():
    """Test multiple invalid choices before valid selection."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    with patch_input(["foo", "-1", "3", "1", ""]):
        codeflash_output = q.ask_auto_now_add_addition("created", "MyModel"); result = codeflash_output # 20.1μs -> 19.2μs (4.88% faster)

def test_multiple_invalid_python_then_valid():
    """Test multiple invalid Python entries before valid."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    with patch_input(["1", "bad", "anotherbad", "timezone.now"]):
        codeflash_output = q.ask_auto_now_add_addition("created", "MyModel"); result = codeflash_output # 30.0μs -> 29.2μs (2.66% faster)

# Large Scale Test Cases

def test_many_invalid_choices_before_valid():
    """Test 50 invalid choices before valid selection."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    invalids = ["foo"] * 50 + ["1", ""]
    with patch_input(invalids):
        codeflash_output = q.ask_auto_now_add_addition("created", "MyModel"); result = codeflash_output # 48.4μs -> 47.8μs (1.22% faster)

def test_many_invalid_python_entries_before_valid():
    """Test 50 invalid python entries before valid."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    invalids = ["1"] + ["bad"] * 50 + ["timezone.now"]
    with patch_input(invalids):
        codeflash_output = q.ask_auto_now_add_addition("created", "MyModel"); result = codeflash_output # 204μs -> 193μs (5.23% faster)

def test_large_field_and_model_names():
    """Test very large field/model names."""
    outbuf = OutputBuffer()
    long_field = "f" * 1000
    long_model = "M" * 1000
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    with patch_input(["1", ""]):
        codeflash_output = q.ask_auto_now_add_addition(long_field, long_model); result = codeflash_output # 14.1μs -> 12.9μs (8.63% faster)

def test_large_number_custom_defaults():
    """Test providing large number of different custom defaults."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    # We'll test 10 different dates
    for i in range(10):
        year = 2000 + i
        with patch_input(["1", f"datetime.datetime({year}, 1, 1)"]):
            codeflash_output = q.ask_auto_now_add_addition("created", "MyModel"); result = codeflash_output

def test_performance_many_calls():
    """Test performance and correctness of 100 calls with default."""
    outbuf = OutputBuffer()
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(outbuf))
    for _ in range(100):
        with patch_input(["1", ""]):
            codeflash_output = q.ask_auto_now_add_addition("created", "MyModel"); result = codeflash_output
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.
#------------------------------------------------
import builtins
import datetime
import io
import sys
# Helper context manager to patch input() and sys.exit for tests
from contextlib import contextmanager

# imports
import pytest
from django.db.migrations.questioner import InteractiveMigrationQuestioner

# --- Minimal stubs for Django's OutputWrapper and timezone for testing ---

class OutputWrapper:
    """
    Minimal stub for Django's OutputWrapper for testing purposes.
    """
    def __init__(self, out, ending="\n"):
        self._out = out
        self.ending = ending
        self.messages = []

    def write(self, msg="", style_func=None, ending=None):
        ending = self.ending if ending is None else ending
        if ending and not msg.endswith(ending):
            msg += ending
        self.messages.append(msg)
        self._out.write(msg)

# Minimal stub for django.utils.timezone
class TimezoneStub:
    @staticmethod
    def now():
        return "MOCKED_TIMEZONE_NOW"

timezone = TimezoneStub()

# --- Unit tests for ask_auto_now_add_addition ---


@contextmanager
def patch_input_exit(inputs, expected_exit=None):
    """
    Patch input() to return values from inputs list, and patch sys.exit to raise SystemExit.
    """
    orig_input = builtins.input
    orig_exit = sys.exit
    input_iter = iter(inputs)
    exit_called = {'called': False, 'code': None}
    def fake_input(prompt=None):
        try:
            return next(input_iter)
        except StopIteration:
            raise EOFError("No more input provided")
    def fake_exit(code=0):
        exit_called['called'] = True
        exit_called['code'] = code
        raise SystemExit(code)
    builtins.input = fake_input
    sys.exit = fake_exit
    try:
        yield exit_called
    finally:
        builtins.input = orig_input
        sys.exit = orig_exit

# --- BASIC TEST CASES ---


def test_choose_provide_default_accept_default():
    """
    User selects option 1 (provide default), then presses Enter to accept default.
    Should return timezone.now (as evaluated).
    """
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    # First input: '1' (choose to provide default), second input: '' (accept default)
    with patch_input_exit(['1', '']):
        codeflash_output = q.ask_auto_now_add_addition("created_at", "MyModel"); result = codeflash_output # 16.2μs -> 14.8μs (9.47% faster)

def test_choose_provide_default_custom_value():
    """
    User selects option 1 (provide default), then enters custom valid Python code.
    Should return the evaluated value.
    """
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    # First input: '1', second input: '42'
    with patch_input_exit(['1', '42']):
        codeflash_output = q.ask_auto_now_add_addition("created_at", "MyModel"); result = codeflash_output # 13.4μs -> 12.2μs (10.2% faster)

def test_choose_quit_exits():
    """
    User selects option 2 (quit). Should call sys.exit(3).
    """
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    # First input: '2'
    with pytest.raises(SystemExit) as excinfo, patch_input_exit(['2']) as exit_called:
        q.ask_auto_now_add_addition("created_at", "MyModel")

# --- EDGE TEST CASES ---

def test_invalid_choice_then_valid_choice():
    """
    User enters invalid (non-integer) input, then valid choice.
    Should reprompt and then proceed.
    """
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    # First input: 'foo' (invalid), second input: '1', third input: '' (accept default)
    with patch_input_exit(['foo', '1', '']):
        codeflash_output = q.ask_auto_now_add_addition("created_at", "MyModel"); result = codeflash_output # 18.5μs -> 17.6μs (5.07% faster)

def test_choice_out_of_range_then_valid():
    """
    User enters number out of range, then valid choice.
    Should reprompt and then proceed.
    """
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    # First input: '0' (invalid), second input: '3' (invalid), third: '1', fourth: '' (accept default)
    with patch_input_exit(['0', '3', '1', '']):
        codeflash_output = q.ask_auto_now_add_addition("created_at", "MyModel"); result = codeflash_output # 14.0μs -> 13.6μs (3.26% faster)

def test_keyboard_interrupt_on_choice():
    """
    User triggers KeyboardInterrupt at choice prompt. Should exit with code 1.
    """
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    def fake_input(prompt=None):
        raise KeyboardInterrupt()
    orig_input = builtins.input
    orig_exit = sys.exit
    def fake_exit(code=0):
        raise SystemExit(code)
    builtins.input = fake_input
    sys.exit = fake_exit
    try:
        with pytest.raises(SystemExit) as excinfo:
            q.ask_auto_now_add_addition("created_at", "MyModel")
    finally:
        builtins.input = orig_input
        sys.exit = orig_exit

def test_keyboard_interrupt_on_default():
    """
    User selects to provide default, then triggers KeyboardInterrupt at default prompt.
    Should exit with code 1.
    """
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    # First input: '1' (provide default), then KeyboardInterrupt
    inputs = iter(['1'])
    def fake_input(prompt=None):
        try:
            return next(inputs)
        except StopIteration:
            raise KeyboardInterrupt()
    orig_input = builtins.input
    orig_exit = sys.exit
    def fake_exit(code=0):
        raise SystemExit(code)
    builtins.input = fake_input
    sys.exit = fake_exit
    try:
        with pytest.raises(SystemExit) as excinfo:
            q.ask_auto_now_add_addition("created_at", "MyModel")
    finally:
        builtins.input = orig_input
        sys.exit = orig_exit

def test_default_prompt_exit_string():
    """
    User selects to provide default, then enters 'exit' string.
    Should exit with code 1.
    """
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    # First input: '1', second input: 'exit'
    with pytest.raises(SystemExit) as excinfo, patch_input_exit(['1', 'exit']) as exit_called:
        q.ask_auto_now_add_addition("created_at", "MyModel")

def test_default_prompt_invalid_python_then_valid():
    """
    User selects to provide default, enters invalid Python (raises exception), then valid Python.
    Should reprompt after error and finally return valid value.
    """
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    # First input: '1', second: 'not_a_var' (NameError), third: '7'
    with patch_input_exit(['1', 'not_a_var', '7']):
        codeflash_output = q.ask_auto_now_add_addition("created_at", "MyModel"); result = codeflash_output # 25.6μs -> 25.4μs (1.02% faster)

def test_default_prompt_empty_then_valid():
    """
    User selects to provide default, enters empty string (should prompt again), then valid Python.
    """
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    # First input: '1', second: '', third: '8'
    with patch_input_exit(['1', '', '8']):
        codeflash_output = q.ask_auto_now_add_addition("created_at", "MyModel"); result = codeflash_output # 16.3μs -> 15.2μs (7.49% faster)

# --- LARGE SCALE TEST CASES ---

def test_many_invalid_choices_then_valid():
    """
    User enters many invalid choices before finally entering a valid one.
    Ensures function can handle repeated invalid input gracefully.
    """
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    # 10 invalid inputs, then '1', then '' (accept default)
    inputs = ['foo'] * 10 + ['1', '']
    with patch_input_exit(inputs):
        codeflash_output = q.ask_auto_now_add_addition("created_at", "MyModel"); result = codeflash_output # 22.8μs -> 22.7μs (0.630% faster)

def test_many_invalid_python_then_valid():
    """
    User enters many invalid Python expressions at default prompt, then valid.
    """
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    # First input: '1', then 10 invalid, then '9'
    inputs = ['1'] + ['bad_code'] * 10 + ['9']
    with patch_input_exit(inputs):
        codeflash_output = q.ask_auto_now_add_addition("created_at", "MyModel"); result = codeflash_output # 54.5μs -> 53.4μs (2.06% faster)

def test_large_scale_repeated_calls():
    """
    Call the function multiple times in succession to check for state leakage or memory issues.
    """
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    for i in range(20):  # Reasonable upper bound for unit test
        with patch_input_exit(['1', str(i)]):
            codeflash_output = q.ask_auto_now_add_addition("created_at", "MyModel"); result = codeflash_output

def test_long_field_and_model_names():
    """
    Use very long field and model names to check for handling of large strings.
    """
    field_name = "f" * 500
    model_name = "M" * 500
    q = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    with patch_input_exit(['1', '']):
        codeflash_output = q.ask_auto_now_add_addition(field_name, model_name); result = codeflash_output # 14.0μs -> 13.2μs (5.86% faster)

def test_multiple_instances_independent():
    """
    Create multiple InteractiveMigrationQuestioner instances and ensure they are independent.
    """
    q1 = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    q2 = InteractiveMigrationQuestioner(prompt_output=OutputWrapper(io.StringIO()))
    with patch_input_exit(['1', '123']):
        codeflash_output = q1.ask_auto_now_add_addition("created_at", "ModelA"); result1 = codeflash_output # 11.3μs -> 10.7μs (5.59% faster)
    with patch_input_exit(['1', '456']):
        codeflash_output = q2.ask_auto_now_add_addition("created_at", "ModelB"); result2 = codeflash_output # 6.40μs -> 5.95μs (7.53% faster)
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.

To edit these changes git checkout codeflash/optimize-InteractiveMigrationQuestioner.ask_auto_now_add_addition-mh6oagq7 and push.