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# tests/test_fastpath.py
from __future__ import annotations
import gc
import io
import itertools
import re
import sys
import typing
import pytest
import progressbar
_ANSI_ESCAPE = re.compile(r'\x1b\[[0-9;]*m')
_PERCENT = re.compile(r'(\d+)%')
def _drawn_percentages(repaints: list[str]) -> list[int]:
"""Extract the integer percentage rendered in each repaint frame.
The ``Percentage`` widget renders e.g. `` 4%|###...`` (no space before the
bar), so the ``%`` token is glued to the bar body; a regex is more robust
than whitespace tokenization.
"""
out: list[int] = []
for frame in repaints:
match = _PERCENT.search(_ANSI_ESCAPE.sub('', frame))
if match:
out.append(int(match.group(1)))
return out
def _assert_cadence_parity(gated: list[str], ungated: list[str]) -> None:
"""Assert the gated run kept the ungated run's rate-limited cadence.
This is the correct equivalence criterion (NOT byte-exact frames): the gate
may legitimately differ by a frame or two: its step is sized by time,
but it must not silently drop a large fraction of redraws the way the
original regression did (16 gated vs. 25 ungated buckets, a ~36% drop). The
checks below fail for such a gate while tolerating the benign +/-1 frame
wobble of the closed loop.
"""
g_count = len(gated)
u_count = len(ungated)
# 1) Rate-limited cadence parity: counts within a frame or two of each
# other. A ~36% drop (e.g. 21 vs 33) fails this by a wide margin.
assert abs(g_count - u_count) <= 2, (
f'gated redraw count {g_count} diverged from ungated {u_count} '
f'beyond rate-limited wobble'
)
# Sanity: the slow loop really did redraw many distinct frames, so the
# comparison is meaningful (not "both drew nothing").
assert len(set(gated)) > 10
g_pcts = _drawn_percentages(gated)
u_pcts = _drawn_percentages(ungated)
assert g_pcts, 'no percentage tokens found in gated frames'
# 2) Monotonic and reaches 100% at the end.
assert g_pcts == sorted(g_pcts), (
f'gated percentages not monotonic: {g_pcts}'
)
assert g_pcts[-1] == 100, f'gated did not reach 100%: {g_pcts[-1]}'
# 3) No large gap: ignoring the final jump to 100% (the loop only covers
# part of the range, then finish() snaps to 100%), no consecutive
# percentages is farther apart than a small multiple of the ungated
# per-redraw window. A gate that drops whole stretches of the bar shows
# up as an oversized inner gap here.
inner_gaps = [g_pcts[i + 1] - g_pcts[i] for i in range(len(g_pcts) - 2)]
ungated_window = max(
(u_pcts[i + 1] - u_pcts[i] for i in range(len(u_pcts) - 2)),
default=1,
)
if inner_gaps:
assert max(inner_gaps) <= 3 * max(ungated_window, 1), (
f'gated skipped a stretch of the bar: max inner gap '
f'{max(inner_gaps)} > 3x ungated window {ungated_window}'
)
class RecordingTTY(io.StringIO):
"""A fake terminal that records each repaint (\\r-delimited write)."""
def isatty(self) -> bool:
return True
def repaints(self) -> list[str]:
# Each redraw starts with '\r'; split and drop the empty head.
return [p for p in self.getvalue().split('\r') if p]
def run_iter(n: int, **kwargs: typing.Any) -> tuple[RecordingTTY, list[int]]:
fd = RecordingTTY()
seen = list(progressbar.progressbar(range(n), fd=fd, **kwargs))
return fd, seen
def test_iterates_all_items_in_order():
_, seen = run_iter(2000)
assert seen == list(range(2000))
def test_value_is_live_during_iteration():
fd = RecordingTTY()
bar = progressbar.ProgressBar(max_value=500, fd=fd)
last = -1
for i in bar(range(500)):
# bar.value == i: value reflects items yielded so far (pre-increment),
# so at the start of the body for item i, value is i (not i+1).
assert bar.value == i, f'bar.value mismatch at i={i}: got {bar.value}'
# previous_value stays byte-identical to the pre-gate behavior on
# EVERY iteration (not just at redraws): the value before the current
# one (0 for the first item, set by start()'s forced draw).
expected_prev = i - 1 if i else 0
assert bar.previous_value == expected_prev, (
f'previous_value mismatch at i={i}: got {bar.previous_value}'
)
last = i
assert last == 499
def test_final_repaint_reaches_completion():
fd, _ = run_iter(1000)
repaints = fd.repaints()
assert repaints, 'expected at least one repaint'
assert '100%' in repaints[-1]
def test_repaints_are_monotonic_in_percentage():
fd, _ = run_iter(5000)
pcts = []
for p in fd.repaints():
# Repaints contain ANSI color codes; strip before tokenizing.
plain = _ANSI_ESCAPE.sub('', p)
for tok in plain.split():
if tok.endswith('%'):
pcts.append(float(tok[:-1]))
break
assert pcts, 'expected at least one percentage token in repaints'
assert pcts == sorted(pcts), 'percentage went backwards'
assert pcts[0] >= 0 and pcts[-1] == 100.0
def test_empty_iterable_finishes_cleanly():
fd, seen = run_iter(0)
assert seen == []
assert fd.getvalue() != '' # start+finish still draw
def test_single_item():
fd, seen = run_iter(1)
assert seen == [0]
assert '100%' in fd.repaints()[-1]
def test_early_break_finishes_dirty():
fd = RecordingTTY()
bar = progressbar.ProgressBar(max_value=1000, fd=fd)
for i in bar(range(1000)):
if i == 10:
break
del bar # trigger GeneratorExit cleanup path (issue #212)
gc.collect()
# A dirty finish must NOT jump the bar to 100%.
assert '100%' not in fd.repaints()[-1]
def test_exception_in_body_propagates_and_finishes():
fd = RecordingTTY()
bar = progressbar.ProgressBar(max_value=1000, fd=fd)
class BoomError(Exception):
pass
with pytest.raises(BoomError):
for i in bar(range(1000)):
if i == 5:
raise BoomError
gc.collect()
assert fd.getvalue() != ''
def fixed_clock(monkeypatch, dt: float):
"""Patch the timer used by bar.py to advance by `dt` per read."""
bar_module = progressbar.bar
counter = itertools.count()
def fake_timer() -> float:
return next(counter) * dt
monkeypatch.setattr(bar_module.timeit, 'default_timer', fake_timer)
def test_redraw_count_is_rate_limited(monkeypatch):
# ~1ms per timer read, 50ms min_poll_interval => far fewer redraws than N.
fixed_clock(monkeypatch, dt=0.001)
fd, _ = run_iter(20000)
n_repaints = len(fd.repaints())
assert 1 < n_repaints < 2000, n_repaints # not one-per-iteration
def test_gate_state_initialized():
bar = progressbar.ProgressBar(max_value=100)
assert bar._gate_enabled is True
assert bar._gate_step >= 1
assert bar._next_update == 0
assert bar._last_drawn_value is None
def _controlled_clock(monkeypatch) -> list[float]:
"""Patch bar.py's timer to read one mutable value; return that list."""
clock = [0.0]
monkeypatch.setattr(
progressbar.bar.timeit, 'default_timer', lambda: clock[0]
)
return clock
def test_gate_calibrates_step_from_measured_rate(monkeypatch):
# The gate calibrates _gate_step from the value/time elapsed between two
# redraws (no separate _gate_last_* state needed). UnknownLength makes any
# value advance redraw (rate-limited), so the measurement is deterministic.
clock = _controlled_clock(monkeypatch)
bar = progressbar.ProgressBar(
max_value=progressbar.UnknownLength, fd=RecordingTTY()
)
bar.min_poll_interval = 0.05
bar.start() # forced draw at t=0; no prior sample, so step stays 1
assert bar._gate_step == 1
clock[0] = 0.10 # 0.10 s later
bar.update(1000) # redraw: 1000 iters over 0.10 s
# step = int((1000 - 0) * min_poll_interval / interval) = 1000*0.05/0.10
assert bar._gate_step == 500
assert bar._next_update == 1000 + 500
def test_gate_backs_off_when_calibrated_and_no_redraw(monkeypatch):
clock = _controlled_clock(monkeypatch)
bar = progressbar.ProgressBar(
max_value=progressbar.UnknownLength, fd=RecordingTTY()
)
bar.min_poll_interval = 0.05
bar.start()
clock[0] = 0.10
bar.update(1000) # calibrate: step=500, _next_update=1500
step = bar._gate_step
assert step == 500
# Time frozen: an update past the threshold finds delta == 0 (no redraw),
# so the gate backs off (doubles the step) instead of re-checking often.
bar.update(1500)
assert bar._gate_step == step * 2
assert bar._next_update == 1500 + step * 2
def test_previous_value_tracks_last_redraw(monkeypatch):
fixed_clock(monkeypatch, dt=0.001)
bar = progressbar.ProgressBar(max_value=10000, fd=RecordingTTY())
bar.start()
drawn: list[int] = []
real_parents = bar._update_parents
def spy(value):
real_parents(value)
drawn.append(bar.value)
bar._update_parents = spy
for i in range(1, 10001):
bar.update(i)
bar.finish()
# previous_value must equal one of the actually-drawn values, not i-1.
assert bar.previous_value in drawn
def test_last_drawn_value_pinned_on_skipped_update(monkeypatch):
"""The gate's pixel reference advances only when a redraw happens.
`_last_drawn_value` (the private pixel reference used by `_needs_update`)
must stay pinned to the value at the last actual draw, even as later
`update()` calls advance `self.value` without redrawing. The public
`previous_value` keeps its original meaning: the value before the most
recent `update()` call.
After a draw at value=3 (from 0) and two rate-limited skips at 4 then 5:
_last_drawn_value == 3 (pinned to the drawn value, for pixel check)
previous_value == 4 (value before the update(5) call)
"""
bar_module = progressbar.bar
# Freeze-then-advance clock: start at 0, jump to 1.0 so update(3) draws,
# then keep it at 1.0 so subsequent updates are rate-limited (skipped).
_time: list[float] = [0.0]
def timer() -> float:
return _time[0]
monkeypatch.setattr(bar_module.timeit, 'default_timer', timer)
bar = progressbar.ProgressBar(max_value=100, fd=RecordingTTY())
bar.start() # _last_update_timer = 0.0
# Advance time far past min_poll_interval (0.05 s) => update(3) draws.
_time[0] = 1.0
bar.update(3)
assert bar._last_drawn_value == 3 # a redraw happened at value 3
# Time frozen at 1.0: delta == 0 => _needs_update() returns False, so the
# next updates advance self.value but do not redraw.
bar.update(4)
bar.update(5)
# Pixel reference stays at the last drawn value; public previous_value
# tracks the value before the most recent update() call.
assert bar._last_drawn_value == 3, (
f'_last_drawn_value should stay at last-drawn (3), '
f'got {bar._last_drawn_value!r}'
)
assert bar.value == 5 # liveness preserved on the manual path
assert bar.previous_value == 4 # value before update(5)
def test_gate_disabled_skips_calibration():
"""When _gate_enabled is False the gate is never (re)calibrated."""
bar = progressbar.ProgressBar(max_value=100, fd=RecordingTTY())
bar.start()
bar._gate_enabled = False
initial_next = bar._next_update
bar.update(50)
# Neither the calibration nor the back-off branch runs: _next_update is
# left untouched while the fast path is disabled.
assert bar._next_update == initial_next
@pytest.mark.no_freezegun
def test_manual_update_skips_clock_when_gated(monkeypatch):
bar_module = progressbar.bar
reads: dict[str, int] = {'n': 0}
real = bar_module.timeit.default_timer
def counting() -> float:
reads['n'] += 1
return real()
bar = progressbar.ProgressBar(max_value=10**7, fd=RecordingTTY())
bar.start()
monkeypatch.setattr(bar_module.timeit, 'default_timer', counting)
before = reads['n']
for i in range(1, 1_000_001):
bar.update(i)
reads_during = reads['n'] - before
bar.finish()
# Far fewer clock reads than updates (gate skips the common path).
assert reads_during < 100_000, reads_during
def _iter_clock(monkeypatch, dt: float) -> dict[str, int]:
"""Patch the timer so its value depends on a shared loop ITERATION.
Unlike ``fixed_clock`` (which ties time to the *number of reads*), this
makes the clock return ``state['i'] * dt`` regardless of how many times
it is read. The gated and ungated bars read the clock a different number
of times, so a per-read clock would make them diverge for the wrong
reason. Tying time to the iteration index keeps both runs seeing the
exact same wall time at every iteration.
"""
bar_module = progressbar.bar
state: dict[str, int] = {'i': 0}
monkeypatch.setattr(
bar_module.timeit,
'default_timer',
lambda: state['i'] * dt,
)
return state
def _drawn_frames(
disable_gate: bool,
monkeypatch,
*,
widgets: list | None = None,
dt: float = 0.06,
n: int = 4000,
maxv: int = 10_000,
) -> list[str]:
state = _iter_clock(monkeypatch, dt)
fd = RecordingTTY()
if widgets is None:
# poll_interval stays None for this widget set, which is the case
# that exposed the uncalibrated back-off bug.
widgets = [progressbar.Percentage(), progressbar.Bar()]
bar = progressbar.ProgressBar(max_value=maxv, fd=fd, widgets=widgets)
bar.start()
if disable_gate:
bar._gate_enabled = False
for i in range(1, n + 1):
state['i'] = i # advance wall time per ITERATION
bar.update(i)
bar.finish()
return fd.repaints()
def test_gated_matches_ungated_drawn_frames(monkeypatch):
"""The gate must keep the ungated rate-limited cadence (manual path).
For a ``poll_interval is None`` bar over a slow loop (``dt`` >=
``min_poll_interval`` so a redraw is due at each item), a gated bar must
redraw at the same rate-limited cadence as an identical bar with the gate
disabled. This is the reviewer's repro of the regression where the gate
dropped ~36% of the buckets the baseline rendered.
The criterion is rate-limited cadence parity, NOT byte-exact frames: the
closed-loop gate sizes its step by time, so a +/-1 frame wobble is benign
and expected. ``_assert_cadence_parity`` tolerates that wobble while still
failing for a gate that drops a large fraction of redraws.
"""
with monkeypatch.context() as m:
gated = _drawn_frames(False, m)
with monkeypatch.context() as m:
ungated = _drawn_frames(True, m)
_assert_cadence_parity(gated, ungated)
def _drawn_frames_iter(
disable_gate: bool,
monkeypatch,
*,
widgets: list | None = None,
dt: float = 0.06,
n: int = 4000,
maxv: int = 10_000,
) -> list[str]:
"""Drive the bar through its ITERATOR path and record drawn frames.
Mirrors ``_drawn_frames`` but uses ``ProgressBar.__iter__`` (the iterator
fast path) instead of manual ``update()`` calls. ``__iter__`` skips
``start()`` when ``start_time`` is already set, so we call ``start()``
explicitly first (which resets the gate via ``init()``), then flip
``_gate_enabled`` to choose gated vs. ungated. Both runs share the same
iteration-driven clock so they observe identical wall time per iteration.
"""
state = _iter_clock(monkeypatch, dt)
fd = RecordingTTY()
if widgets is None:
# poll_interval stays None for this widget set, which is the case
# that exposed the uncalibrated back-off bug in the iterator path.
widgets = [progressbar.Percentage(), progressbar.Bar()]
bar = progressbar.ProgressBar(max_value=maxv, fd=fd, widgets=widgets)
bar.start() # resets _gate_enabled via init(); primes start_time
if disable_gate:
bar._gate_enabled = False
class _IterClockRange:
"""An iterable that advances the shared clock once per item.
Returning a fresh iterator each time keeps ``bar.value`` and the
iteration index aligned regardless of how many times the clock is read.
"""
def __len__(self) -> int:
return n
def __iter__(self):
for i in range(n):
state['i'] = i # advance wall time per ITERATION
yield i
# __iter__ does not call start() again because start_time is already set.
for _ in bar(_IterClockRange()):
pass
return fd.repaints()
def test_iterator_gated_matches_ungated_drawn_frames(monkeypatch):
"""The ITERATOR-path gate must keep the ungated rate-limited cadence.
Reviewer's repro of the regression in ``__iter__``: for a
``poll_interval is None`` bar over a slow, iteration-driven clock
(``dt`` >= ``min_poll_interval`` so a redraw is due at each item), the
iterator path's inline gate skipped ``update()`` based on ``_next_update``
with a bogus pre-measurement step, leaping over whole buckets and dropping
redraws the ungated bar rendered.
With the fix (``_gate_step`` starts at 1 so ``__iter__`` calls ``update()``
every iteration until a real measurement grows it), the gated
iterator must redraw at the same rate-limited cadence as an identical bar
driven through the same iterator with the gate disabled. As in the manual
path the criterion is cadence parity, not byte-exact frames.
"""
with monkeypatch.context() as m:
gated = _drawn_frames_iter(False, m)
with monkeypatch.context() as m:
ungated = _drawn_frames_iter(True, m)
_assert_cadence_parity(gated, ungated)
# NOTE: A default-widget bar (poll_interval is set by the Timer/animation
# widgets) intentionally does NOT get a byte-exact equivalence test. Its
# redraws are time-driven, not value-driven, so matching the ungated frame
# sequence would require the gate to read the clock on every call - which is
# precisely the read the gate exists to skip. The correctness obligation only
# binds the value-driven (poll_interval is None) case above, which is also the
# case that exposed the uncalibrated back-off bug.
def test_next_direct_exhaustion_calls_finish():
"""Direct next(bar) still finishes the bar on StopIteration."""
fd = RecordingTTY()
bar = progressbar.ProgressBar(max_value=2, fd=fd)
bar(range(2))
bar.start()
assert next(bar) == 0
assert next(bar) == 1
with pytest.raises(StopIteration):
next(bar) # exhausts iterable, calls finish()
assert '100%' in fd.repaints()[-1]
def test_shortcut_has_single_generator_layer():
import types
gen = progressbar.progressbar(range(3), fd=RecordingTTY())
assert isinstance(gen, types.GeneratorType)
# It is the bar's own iterator generator, not a wrapper: compare the
# generator's code object to ProgressBar._iter_python (the pure-Python
# path `__iter__` dispatches to; robust across versions). The autouse
# `disable_native_accelerator` fixture forces this path here.
assert gen.gi_code is progressbar.ProgressBar._iter_python.__code__
def test_env_disables_fastpath(monkeypatch):
monkeypatch.setenv('PROGRESSBAR_DISABLE_FASTPATH', '1')
bar = progressbar.ProgressBar(max_value=100, fd=RecordingTTY())
bar.start()
assert bar._gate_enabled is False
def test_zero_min_poll_interval_disables_gate():
# Build a bar and force min_poll_interval to zero on the *instance* (not
# the class) before calling start(), so the class version-tag is
# untouched and CPython's adaptive specialiser for __iter__ is not
# disturbed.
bar = progressbar.ProgressBar(max_value=100, fd=RecordingTTY())
bar.min_poll_interval = 0.0 # instance-level override, zero rate-limit
bar.start()
# With no rate limit the user wants every update considered.
assert bar._gate_enabled is False
@pytest.mark.no_freezegun
@pytest.mark.skipif(
sys.gettrace() is not None,
reason='coverage tracing inflates per-iteration cost; benchmark skipped',
)
def test_iterator_overhead_is_low():
import timeit as _t
# Use the REAL clock (no fixed_clock): under a frozen clock (dt == 0) the
# corrected gate never calibrates, so update() runs every iteration and the
# measurement no longer reflects the gated fast path. A real, advancing
# `perf_counter` lets the gate calibrate and skip as it does in production.
fd = RecordingTTY()
n = 200_000
t = min(
_t.timeit(
lambda: [None for _ in progressbar.progressbar(range(n), fd=fd)],
number=1,
)
for _ in range(3)
)
ns = t / n * 1e9
# Generous smoke gate only; the authoritative per-iteration budget is
# enforced in tests/test_perf_budget.py (Task 8).
assert ns < 200, f'{ns:.1f} ns/iter (real clock)'
def test_no_color_fast_path_and_ansi():
# Render-cost optimization adds a no-ESC fast path to no_color/len_color.
# It must be identical to the regex path for both plain and ANSI input.
utils = progressbar.utils
# Fast path (no ESC byte): returned unchanged, str and bytes.
assert utils.no_color('plain text') == 'plain text'
assert utils.no_color(b'plain bytes') == b'plain bytes'
assert utils.len_color('plain') == 5
# Regex path (ANSI present): escape sequences stripped, str and bytes.
assert utils.no_color('\x1b[31mred\x1b[0m') == 'red'
assert utils.no_color(b'\x1b[31mred\x1b[0m') == b'red'
assert utils.len_color('\x1b[1mbold\x1b[0m') == 4
def test_no_color_patterns_are_precompiled():
# F5: the str and bytes ANSI patterns are compiled once at module import,
# not rebuilt on every no_color() call (which runs per widget per redraw).
utils = progressbar.utils
assert isinstance(utils._ANSI_COLOR_RE, re.Pattern)
assert isinstance(utils._ANSI_COLOR_RE_BYTES, re.Pattern)
# Both variants must still strip ANSI correctly.
assert utils.no_color('\x1b[32mgreen\x1b[0m') == 'green'
assert utils.no_color(b'\x1b[32mgreen\x1b[0m') == b'green'
def test_render_output_stable(monkeypatch):
# Guard the default-widget render path against the render-cost
# optimization changing appearance: the final repaint must reach 100%.
fixed_clock(monkeypatch, dt=10.0) # force a redraw on every forced update
fd = RecordingTTY()
bar = progressbar.ProgressBar(max_value=100, fd=fd)
bar.start()
for i in range(1, 101):
bar.update(i, force=True)
bar.finish()
repaints = fd.repaints()
assert repaints
last = _ANSI_ESCAPE.sub('', repaints[-1])
assert last.strip().startswith('100%')