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CSSFrancis merged 1 commit into from
Oct 23, 2026
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tests: make GPU/CPU parity checks robust to a late frame #86

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45 changes: 34 additions & 11 deletions anyplotlib/tests/test_plot2d/test_gpu_parity_playwright.py
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Original file line number Diff line number Diff line change
Expand Up @@ -105,6 +105,29 @@ def _assert_parity(name, arr_gpu, arr_cpu, *, tol=10, max_diff_frac=0.005):
assert ok, f"{name}: GPU render diverged from Canvas2D reference — {msg}"


def _assert_page_parity(name, page_gpu, page_cpu, *, tol=10,
max_diff_frac=0.005, timeout_ms=3000):
""":func:`_assert_parity` on live pages, re-snapshotting until it holds.

``_settle`` waits a fixed interval, which a loaded CI runner can outlast:
one page then still shows a transient frame while its state already
matches the other's (seen once on macOS / Python 3.13 after a mouse pan,
0.8 % of pixels). A real coordinate bug moves whole image regions and
never converges, so it still fails once the timeout runs out.
"""
waited = 0
while True:
arr_gpu, arr_cpu = _snap(page_gpu), _snap(page_cpu)
ok, _ = compare_arrays(arr_gpu, arr_cpu, tol=tol,
max_diff_frac=max_diff_frac)
if ok or waited >= timeout_ms:
break
_settle(page_gpu); _settle(page_cpu)
waited += 300
_assert_parity(name, arr_gpu, arr_cpu, tol=tol,
max_diff_frac=max_diff_frac)


def _assert_gpu_active(page, expect=True):
diag = page.evaluate("() => globalThis.__apl_gpu2d || {}")
assert diag, "no 2-D GPU diagnostic recorded"
Expand Down Expand Up @@ -137,15 +160,15 @@ def test_rest_parity(self, gpu_interact_page):
_settle(pg); _settle(pc)
_assert_gpu_active(pg)
_assert_gpu_active(pc, expect=False)
_assert_parity("rest", _snap(pg), _snap(pc))
_assert_page_parity("rest", pg, pc)

def test_zoom_in_centred_parity(self, gpu_interact_page):
pg, pc, p_gpu, p_cpu = _make_pair(gpu_interact_page)
for page, plot in ((pg, p_gpu), (pc, p_cpu)):
_set_zoom(page, plot, 3.0, 0.5, 0.5)
_settle(page)
_assert_gpu_active(pg) # GPU must NOT fall back on zoom
_assert_parity("zoom-in centred", _snap(pg), _snap(pc))
_assert_page_parity("zoom-in centred", pg, pc)

def test_pan_y_parity(self, gpu_interact_page):
# Vertically OFF-CENTRE window — the historical v-mirror bug shows here.
Expand All @@ -154,23 +177,23 @@ def test_pan_y_parity(self, gpu_interact_page):
_set_zoom(page, plot, 3.0, 0.5, 0.22)
_settle(page)
_assert_gpu_active(pg)
_assert_parity("pan-y (off-centre v window)", _snap(pg), _snap(pc))
_assert_page_parity("pan-y (off-centre v window)", pg, pc)

def test_pan_x_parity(self, gpu_interact_page):
pg, pc, p_gpu, p_cpu = _make_pair(gpu_interact_page)
for page, plot in ((pg, p_gpu), (pc, p_cpu)):
_set_zoom(page, plot, 3.0, 0.2, 0.5)
_settle(page)
_assert_gpu_active(pg)
_assert_parity("pan-x (off-centre u window)", _snap(pg), _snap(pc))
_assert_page_parity("pan-x (off-centre u window)", pg, pc)

def test_pan_corner_parity(self, gpu_interact_page):
pg, pc, p_gpu, p_cpu = _make_pair(gpu_interact_page)
for page, plot in ((pg, p_gpu), (pc, p_cpu)):
_set_zoom(page, plot, 4.0, 0.85, 0.8)
_settle(page)
_assert_gpu_active(pg)
_assert_parity("pan corner", _snap(pg), _snap(pc))
_assert_page_parity("pan corner", pg, pc)

def test_zoom_out_parity(self, gpu_interact_page):
# zoom < 1: the dest-rect (letterbox shrink) branch of the uniform.
Expand All @@ -179,7 +202,7 @@ def test_zoom_out_parity(self, gpu_interact_page):
_set_zoom(page, plot, 0.75, 0.5, 0.5)
_settle(page)
_assert_gpu_active(pg)
_assert_parity("zoom-out", _snap(pg), _snap(pc))
_assert_page_parity("zoom-out", pg, pc)


class TestGpuMousePanParity:
Expand All @@ -194,7 +217,7 @@ def test_wheel_zoom_then_drag_pan(self, gpu_interact_page):
for _ in range(6):
page.mouse.wheel(0, -120)
_settle(page)
_assert_parity("mouse wheel zoom", _snap(pg), _snap(pc))
_assert_page_parity("mouse wheel zoom", pg, pc)

# Drag DOWN: image content must move down (view up) on BOTH paths.
for page in (pg, pc):
Expand All @@ -209,7 +232,7 @@ def test_wheel_zoom_then_drag_pan(self, gpu_interact_page):
assert st_g["center_x"] == st_c["center_x"]
assert st_g["center_y"] == st_c["center_y"]
_assert_gpu_active(pg)
_assert_parity("mouse pan down", _snap(pg), _snap(pc))
_assert_page_parity("mouse pan down", pg, pc)

# Then drag RIGHT while still vertically off-centre.
for page in (pg, pc):
Expand All @@ -219,7 +242,7 @@ def test_wheel_zoom_then_drag_pan(self, gpu_interact_page):
page.mouse.up()
_settle(page)
_assert_gpu_active(pg)
_assert_parity("mouse pan right", _snap(pg), _snap(pc))
_assert_page_parity("mouse pan right", pg, pc)

def test_pan_direction_moves_content_with_cursor(self, gpu_interact_page):
"""Row-profile check independent of the CPU reference: dragging DOWN
Expand Down Expand Up @@ -326,7 +349,7 @@ def test_marker_composite_parity_zoom_pan(self, gpu_interact_page):
_set_zoom(page, plot, 2.5, 0.6, 0.3)
_settle(page)
_assert_gpu_active(pg)
_assert_parity("markers over zoom/pan", _snap(pg), _snap(pc))
_assert_page_parity("markers over zoom/pan", pg, pc)


class TestGpuWidgetParity:
Expand Down Expand Up @@ -372,7 +395,7 @@ def test_widget_drag_same_result_and_pixels(self, gpu_interact_page):
f"widget {k} diverged: gpu={w_g[k]} cpu={w_c[k]}"
)
_assert_gpu_active(pg)
_assert_parity("widget drag composite", _snap(pg), _snap(pc))
_assert_page_parity("widget drag composite", pg, pc)


# ---------------------------------------------------------------------------
Expand Down
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