feat: animated-QR transfer, Android reader, relative-locktime preservation, karen7 hermetic tests

2026-09-14 09:11:50 -04:00
parent 9c4697c923
commit fb88d7540c
82 changed files with 11665 additions and 3116 deletions
--- a/tests/test_gui_qr_transfer.py
+++ b/tests/test_gui_qr_transfer.py
@@ -0,0 +1,760 @@
+"""
+Tests for the QR / audio will-transfer dialogs (``bal.gui.qt.dialogs``).
+
+Covers the unified ``WillExportDialog`` (transport radios, stacked pages,
+QR build/navigation, chunk-size / autoplay, filter revert) and the unified
+``WillImportDialog`` (QR frame capture, slot grid, complete-review enabling,
+total mismatch reset, frame assembly -> decode). The wizard and the
+camera/audio paths need a live wallet/hardware and are exercised only
+through the shared frame-assembly path here.
+
+Run:
+    QT_QPA_PLATFORM=offscreen python3 tests/test_gui_qr_transfer.py
+"""
+
+import base64
+import json
+import sys
+from unittest.mock import MagicMock, patch
+
+sys.path.insert(0, __file__.rsplit("/", 2)[0])
+
+from electrum.transaction import Transaction
+from PyQt6.QtWidgets import QApplication, QMainWindow
+
+import bal.gui.qt.dialogs as dialogs
+from bal.core.qrtransfer import CHUNK_PRESETS, encode_transfer, split_frames
+from bal.core.will import WillItem
+
+_app = QApplication.instance() or QApplication(sys.argv)
+
+# A valid 1x1 transparent PNG, good enough for BalDialog's window icon.
+_PNG_BYTES = base64.b64decode(
+    "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8z8BQDwAEhQGAhKmMIQAAAABJRU5ErkJggg=="
+)
+
+# A valid serialized Bitcoin transaction hex (1 input + 1 P2PKH output),
+# reused for the WillItem status regression test.
+_VALID_TX_HEX = (
+    "01000000012a5c9a94fcde98f5581cd00162c60a13936ceb75389ea65b"
+    "f38633b424eb4031000000006c493046022100a82bbc57a0136751e543"
+    "3f41cf000b3f1a99c6744775e76ec764fb78c54ee100022100f9e80b7d"
+    "e89de861dc6fb0c1429d5da72c2b6b2ee2406bc9bfb1beedd729d98501"
+    "2102e61d176da16edd1d258a200ad9759ef63adf8e14cd97f53227bae3"
+    "5cdb84d2f6ffffffff0140420f00000000001976a914230ac37834073a"
+    "42146f11ef8414ae929feaafc388ac00000000"
+)
+
+
+class _Cfg:
+    def __init__(self, value):
+        self._value = value
+
+    def get(self):
+        return self._value
+
+
+class FakePlugin:
+    # Smallest QR preset: long transfers produce several frames.
+    QR_CHUNK_SIZE = _Cfg(CHUNK_PRESETS[0][1])
+
+    def read_file(self, path):
+        return _PNG_BYTES
+
+
+class FakeWindow(QMainWindow):
+    config = {}
+
+    def format_amount(self, amount):
+        return "{:.8f}".format(amount)
+
+    def format_amount_and_units(self, amount):
+        return "{:.8f} sat".format(amount)
+
+
+class FakeBalWindow:
+    """Duck-typed stand-in for BalWindow (dialog layer only)."""
+
+    def __init__(self):
+        self.window = FakeWindow()
+        self.bal_plugin = FakePlugin()
+        self.willitems = {}
+
+    def get_audio_modem_plugin(self):
+        return None
+
+
+class StubTx:
+    def __init__(self, payload):
+        self.payload = payload
+
+    def txid(self):
+        return "{:064x}".format(hash(self.payload) & 0xFFFFFFFFFFFFFFFF)
+
+    def __str__(self):
+        return self.payload
+
+
+class StubWillItem:
+    def __init__(self, payload, statuses=None):
+        self.tx = StubTx(payload)
+        self.statuses = statuses or {}
+
+    def get_status(self, name):
+        return self.statuses.get(name, False)
+
+    def to_dict(self):
+        return {"tx": str(self.tx), "status": self.statuses}
+
+
+def _make_willitems(n=3, payload_len=120, payloads=None):
+    if payloads is None:
+        payloads = ["T{}".format(i) * payload_len for i in range(n)]
+    return {
+        "item{}".format(i): StubWillItem(p)
+        for i, p in enumerate(payloads)
+    }
+
+
+# ------------------------------------------------------------------ #
+# WillExportDialog (QR transport via d.qr_page)
+# ------------------------------------------------------------------ #
+
+def test_export_dialog_builds():
+    bw = FakeBalWindow()
+    bw.willitems = _make_willitems()
+    d = dialogs.WillExportDialog(bw, bal_plugin=bw.bal_plugin, initial_mode="qr")
+    page = d.qr_page
+    assert d.transport_qr.isChecked()
+    assert page.tx_strings
+    assert page.frames
+    assert len(page.frames) >= 1
+    # Frame 1 is shown.
+    assert page.qr_view.text == page.frames[0]
+    assert "1" in page.progress_label.text()
+    d.close()
+
+
+def test_export_dialog_unified_transports():
+    # One window hosts the three transports as stacked, radio-selected pages.
+    bw = FakeBalWindow()
+    bw.willitems = _make_willitems()
+    d = dialogs.WillExportDialog(bw, bal_plugin=bw.bal_plugin)
+    assert d.stacked.count() == 3
+    assert d.transport_file.isChecked()
+    assert d.stacked.currentWidget() is d.file_page
+    d._on_mode_clicked(d.MODE_QR)
+    assert d.stacked.currentWidget() is d.qr_page
+    d._on_mode_clicked(d.MODE_AUDIO)
+    assert d.stacked.currentWidget() is d.audio_page
+    d.close()
+
+
+def test_import_dialog_qr_page_has_no_audio():
+    # Audio lives on the import dialog's own audio page, never in the QR page.
+    bw = FakeBalWindow()
+    d = dialogs.WillImportDialog(bw, bal_plugin=bw.bal_plugin)
+    page = d.qr_page
+    assert not hasattr(page, "_audio_receive")
+    texts = [b.text() for b in page.findChildren(dialogs.QPushButton)]
+    assert not any("Audio" in t for t in texts)
+    assert d.receive_btn is not None
+    d.close()
+
+
+def test_export_dialog_empty_close():
+    # An empty will shows a modal message and no widgets are built; stub the
+    # message out for the test.
+    orig = dialogs.MessageBoxMixin.show_message
+    dialogs.MessageBoxMixin.show_message = lambda self, msg, icon=None: None
+    try:
+        bw = FakeBalWindow()
+        d = dialogs.WillExportDialog(bw, bal_plugin=bw.bal_plugin)
+        assert not d.isVisible()
+        assert not hasattr(d, "qr_page")
+        d.close()
+    finally:
+        dialogs.MessageBoxMixin.show_message = orig
+
+
+def test_imported_item_status_not_none():
+    # Regression: a WillItem built from a bare {"tx": hex} had a None status,
+    # so set_status (e.g. IMPORTED / INVALIDATED from the import validity
+    # pass) crashed with "unsupported operand type(s) for +=: 'NoneType' and
+    # 'str'".
+    with patch.object(Transaction, "add_info_from_wallet"):
+        wi = WillItem({"tx": _VALID_TX_HEX}, wallet=None)
+        assert wi.status == ""
+        assert wi.set_status("IMPORTED", True) is True
+        assert wi.set_status("INVALIDATED", True) is True
+        assert "Imported" in wi.status and "Invalidated" in wi.status
+
+
+def test_export_auto_scroll():
+    bw = FakeBalWindow()
+    bw.willitems = _make_willitems(n=6, payload_len=400)
+    d = dialogs.WillExportDialog(bw, bal_plugin=bw.bal_plugin, initial_mode="qr")
+    page = d.qr_page
+    assert page.fps_spin is not None
+    assert not page.auto_timer.isActive()
+
+    page.fps_spin.setValue(2)
+    page._toggle_auto()
+    assert page.auto_timer.isActive()
+    assert page.auto_btn.text() == dialogs._("Stop")
+    page._auto_step()
+    assert page.index == 1
+    page._toggle_auto()
+    assert not page.auto_timer.isActive()
+    assert page.auto_btn.text() == dialogs._("Auto")
+
+    # Advancing past the last frame stops the slideshow automatically.
+    page._toggle_auto()
+    page.index = len(page.frames) - 1
+    page._auto_step()
+    assert not page.auto_timer.isActive()
+    d.close()
+
+
+def test_export_auto_scroll_loop():
+    bw = FakeBalWindow()
+    bw.willitems = _make_willitems(n=6, payload_len=400)
+    d = dialogs.WillExportDialog(bw, bal_plugin=bw.bal_plugin, initial_mode="qr")
+    page = d.qr_page
+    assert page.loop_check is not None
+
+    # Loop on: reaching the last code wraps back to the first and keeps going.
+    page.loop_check.setChecked(True)
+    page._toggle_auto()
+    assert page.auto_timer.isActive()
+    page.index = len(page.frames) - 1
+    page._auto_step()
+    assert page.index == 0
+    assert page.auto_timer.isActive()
+    page._toggle_auto()
+
+    # Loop off: reaching the last code stops the slideshow.
+    page.loop_check.setChecked(False)
+    page._toggle_auto()
+    page.index = len(page.frames) - 1
+    page._auto_step()
+    assert not page.auto_timer.isActive()
+    d.close()
+
+
+def test_export_filter_valid_and_valid_nc():
+    bw = FakeBalWindow()
+    a = StubWillItem("A" * 120, statuses={"VALID": True, "COMPLETE": True})
+    b = StubWillItem("B" * 120, statuses={"VALID": True})
+    c = StubWillItem("C" * 120)
+    bw.willitems = {"a": a, "b": b, "c": c}
+    d = dialogs.WillExportDialog(bw, bal_plugin=bw.bal_plugin, initial_mode="qr")
+    page = d.qr_page
+    assert d.filter_combo.count() == 3
+    # Whole-will default: a single JSON document carrying all selected items.
+    assert d.content_check.isChecked()
+    assert len(page.tx_strings) == 1
+    data = json.loads(page.tx_strings[0])
+    assert set(data) == {"a", "b", "c"}
+
+    # Switch to tx-only content, then exercise the filters.
+    d.content_check.setChecked(False)
+    assert len(page.tx_strings) == 3
+
+    # "Valid" filter -> only the valid items (a, b).
+    d._on_filter_change(1)
+    assert sorted(page.tx_strings) == ["A" * 120, "B" * 120]
+
+    # "Valid NC" filter -> only the valid, not-complete item (b).
+    d._on_filter_change(2)
+    assert sorted(page.tx_strings) == ["B" * 120]
+    assert page.qr_view.text == page.frames[0]
+    d.close()
+
+
+def test_export_filter_empty_reverts():
+    bw = FakeBalWindow()
+    # Only a COMPLETE valid item: "Valid NC" selects nothing -> revert.
+    bw.willitems = {
+        "a": StubWillItem("A" * 120, statuses={"VALID": True, "COMPLETE": True})
+    }
+    d = dialogs.WillExportDialog(bw, bal_plugin=bw.bal_plugin, initial_mode="qr")
+    messages = []
+    d.show_message = lambda msg: messages.append(msg)  # type: ignore[assignment]
+    d._on_filter_change(2)  # "Valid NC" -> empty subset
+    assert messages
+    assert d._filter_index == 0  # reverted to "All"
+    assert d.filter_combo.currentIndex() == 0
+    assert len(d.qr_page.tx_strings) == 1
+    d.close()
+
+
+def test_export_navigation_and_chunk_change():
+    # Low-redundancy serialized transactions resist deflate, so even the
+    # compressed best-of transfer still needs several frames at the default
+    # chunk and navigation across frames is exercised.
+    def noisy(pad):
+        return "".join("{:02x}".format((pad * 31 + j * 101 + j * j) % 256) for j in range(200))
+
+    bw = FakeBalWindow()
+    bw.willitems = _make_willitems(
+        n=6, payload_len=400,
+        payloads=["{}0{}".format(noisy(i), "T" * 50) for i in range(6)],
+    )
+    d = dialogs.WillExportDialog(bw, bal_plugin=bw.bal_plugin, initial_mode="qr")
+    page = d.qr_page
+    first_count = len(page.frames)
+    assert first_count > 1  # long transfer, small default chunk
+
+    assert not page.prev_btn.isEnabled()
+    page._next()
+    assert page.index == 1
+    assert page.qr_view.text == page.frames[1]
+    assert page.prev_btn.isEnabled()
+    page._prev()
+    assert page.index == 0
+    assert page.qr_view.text == page.frames[0]
+
+    # Switch to the largest preset: fewer, bigger frames.
+    page._on_chunk_change(len(dialogs.CHUNK_PRESETS) - 1)
+    assert len(page.frames) < first_count
+    assert page.index == 0
+    d.close()
+
+
+# ------------------------------------------------------------------ #
+# WillImportDialog (QR transport via d.qr_page)
+# ------------------------------------------------------------------ #
+
+def test_import_frame_flow():
+    bw = FakeBalWindow()
+    d = dialogs.WillImportDialog(bw, bal_plugin=bw.bal_plugin)
+    page = d.qr_page
+    assert not page.review_btn.isEnabled()
+    assert not page.slot_area.isVisible()
+
+    transfer = encode_transfer(["A" * 120, "B" * 120, "C" * 120])
+    frames = split_frames(transfer, 150)
+    assert len(frames) > 1
+
+    for frame in frames:
+        page._add_frame(frame)
+    assert page.total == len(frames)
+    assert page.review_btn.isEnabled()
+    # isVisible() needs a shown parent; assert the widget is not hidden instead.
+    assert not page.slot_area.isHidden()
+    assert len(page.slot_widgets) == page.total
+    assert "All" in page.status_label.text()
+    # Duplicate capture is harmless.
+    page._add_frame(frames[0])
+    assert len(page.frames) == page.total
+    d.close()
+
+
+def test_import_assembles_and_decodes():
+    bw = FakeBalWindow()
+    d = dialogs.WillImportDialog(bw, bal_plugin=bw.bal_plugin)
+    page = d.qr_page
+    captured = {}
+
+    def fake_finish(payload):
+        captured["payload"] = payload
+
+    page._finish_import = fake_finish
+    transfer = encode_transfer(["P" * 130, "Q" * 130])
+    for frame in split_frames(transfer, 150):
+        page._add_frame(frame)
+    page._review_and_sign()
+    # The payload is rejoined into an opaque string for autodetect.
+    assert captured["payload"].split("\n") == ["P" * 130, "Q" * 130]
+    d.close()
+
+
+def test_decode_will_payload_autodetect():
+    # Whole-will JSON is recognized as a will document.
+    payload = json.dumps({"item1": {"tx": "AAAA", "status": {"VALID": True}}})
+    kind, data = dialogs.decode_will_payload(payload)
+    assert kind == "will"
+    assert data["item1"]["tx"] == "AAAA"
+
+    # A singleton dict whose value is not an item dict falls back to txs.
+    kind, data = dialogs.decode_will_payload('{"foo": 1}')
+    assert kind == "txs"
+
+    # Comma and/or newline separated transactions.
+    kind, data = dialogs.decode_will_payload("AAAA,BBBB\nCCCC")
+    assert kind == "txs"
+    assert data == ["AAAA", "BBBB", "CCCC"]
+
+    # A single transaction with no separators.
+    kind, data = dialogs.decode_will_payload("HEXHEX")
+    assert kind == "txs"
+    assert data == ["HEXHEX"]
+
+
+def test_whole_will_qr_roundtrip():
+    # "Whole will" produces a single JSON document that survives a full
+    # QR encode -> frame capture -> assemble -> decode cycle.
+    bw = FakeBalWindow()
+    items = _make_willitems(2)
+    bw.willitems = items
+    d = dialogs.WillExportDialog(bw, bal_plugin=bw.bal_plugin, initial_mode="qr")
+    page = d.qr_page
+    assert d.content_check.isChecked()
+    assert len(page.tx_strings) == 1
+
+    # Rebuild the transfer from the dialog's own strings, as the importer does.
+    transfer = encode_transfer(page.tx_strings)
+    impl = dialogs.WillImportDialog(bw, bal_plugin=bw.bal_plugin)
+    import_page = impl.qr_page
+    for frame in split_frames(transfer, dialogs.CHUNK_PRESETS[0][1]):
+        import_page._add_frame(frame)
+    assert import_page.review_btn.isEnabled()
+    caught = {}
+
+    def fake_finish(payload):
+        caught["payload"] = payload
+
+    import_page._finish_import = fake_finish
+    import_page._review_and_sign()
+    kind, data = dialogs.decode_will_payload(caught["payload"])
+    assert kind == "will"
+    assert set(data) == {"item0", "item1"}
+    d.close()
+    impl.close()
+
+
+def test_import_total_mismatch_resets():
+    bw = FakeBalWindow()
+    d = dialogs.WillImportDialog(bw, bal_plugin=bw.bal_plugin)
+    page = d.qr_page
+    warnings = []
+    page.show_warning = lambda msg: warnings.append(msg)  # type: ignore[assignment]
+
+    frames_a = split_frames(encode_transfer(["A" * 120, "B" * 120]), 150)
+    frames_b = split_frames(encode_transfer(["A" * 120, "B" * 120, "C" * 120]), 150)
+    for frame in frames_a:
+        page._add_frame(frame)
+    assert page.total == len(frames_a)
+
+    # A frame with a different total wipes the import; the first frame of
+    # the new transfer must be scanned afresh.
+    page._add_frame(frames_b[0])
+    assert warnings
+    assert page.total == 0
+    assert not page.frames
+    assert not page.review_btn.isEnabled()
+    d.close()
+
+
+def test_import_manual_entry():
+    bw = FakeBalWindow()
+    d = dialogs.WillImportDialog(bw, bal_plugin=bw.bal_plugin)
+    page = d.qr_page
+    frames = split_frames(encode_transfer(["M" * 120]), 150)
+    page.manual_edit.setText(frames[0])
+    page._add_from_manual()
+    assert page.manual_edit.text() == ""
+    assert page.total == 1
+    assert page.review_btn.isEnabled()
+    d.close()
+
+
+# ------------------------------------------------------------------ #
+# Continuous camera scan (change/detection debounce + auto-finish)
+# ------------------------------------------------------------------ #
+
+def _fresh_debounce():
+    return {
+        "last_index": None,
+        "last_payload": None,
+        "pending_index": None,
+        "pending_payload": None,
+        "pending_count": 0,
+    }
+
+
+def test_qr_import_debounce_pending_then_accept():
+    s = _fresh_debounce()
+    # First sighting of a new identity: pending, not yet stored.
+    assert dialogs.qr_import_accept_frame(s, "balqr", "balqr:2", 2, 1, "PAYLOAD1") == "pending"
+    assert s["pending_count"] == 1
+    assert s["last_index"] is None
+    # A second stable read of the same identity: accepted.
+    assert dialogs.qr_import_accept_frame(s, "balqr", "balqr:2", 2, 1, "PAYLOAD1") == "accept"
+    assert s["last_index"] == 1
+    assert s["last_payload"] == "PAYLOAD1"
+    assert s["pending_count"] == 0
+
+
+def test_qr_import_debounce_re_reading_last_is_ignored():
+    s = _fresh_debounce()
+    dialogs.qr_import_accept_frame(s, "balqr", "balqr:2", 2, 1, "P1")
+    dialogs.qr_import_accept_frame(s, "balqr", "balqr:2", 2, 1, "P1")  # accepted
+    # The exporter is still showing frame 1: must be ignored, not accepted.
+    assert dialogs.qr_import_accept_frame(s, "balqr", "balqr:2", 2, 1, "P1") == "ignore"
+    assert s["last_index"] == 1
+    assert s["pending_count"] == 0
+
+
+def test_qr_import_debounce_transition_pending_resets():
+    s = _fresh_debounce()
+    dialogs.qr_import_accept_frame(s, "balqr", "balqr:2", 2, 1, "P1")
+    dialogs.qr_import_accept_frame(s, "balqr", "balqr:2", 2, 1, "P1")  # accept frame 1
+    # A new identity interrupts the pending accumulation.
+    assert dialogs.qr_import_accept_frame(s, "balqr", "balqr:2", 2, 2, "P2") == "pending"
+    assert dialogs.qr_import_accept_frame(s, "balqr", "balqr:2", 2, 2, "P2") == "accept"
+    # Same-index duplicate with different payload is treated as new identity.
+    assert dialogs.qr_import_accept_frame(s, "balqr", "balqr:2", 2, 2, "P2") == "ignore"
+
+
+def test_qr_import_debounce_total_mismatch_resets():
+    s = _fresh_debounce()
+    # In-range frame is accepted even though its declared total is ignored.
+    assert dialogs.qr_import_accept_frame(s, "balqr", "balqr:3", 3, 2, "P2") == "pending"
+    assert dialogs.qr_import_accept_frame(s, "balqr", "balqr:3", 3, 2, "P2") == "accept"
+    # A frame that belongs to a different transfer.
+    assert dialogs.qr_import_accept_frame(s, "balqr", "balqr:4", 4, 2, "P2B") == "reset"
+    # Once the policy is rebased on the new transfer, frames resume normally
+    # (the widget clears the debounce while wiping the import).
+    s["key"] = None
+    assert dialogs.qr_import_accept_frame(s, "balqr", "balqr:4", 4, 2, "P2B") == "pending"
+
+
+def test_qr_import_handle_scanned_text_autofinish():
+    bw = FakeBalWindow()
+    d = dialogs.WillImportDialog(bw, bal_plugin=bw.bal_plugin)
+    page = d.qr_page
+    reviewed = []
+    page._review_and_sign = lambda: reviewed.append(True)  # type: ignore[assignment]
+
+    frames = split_frames(encode_transfer(["A" * 120, "B" * 120]), 150)
+    assert len(frames) > 1
+
+    # The camera session is running and every frame needs two stable reads.
+    page._scanning = True
+    for frame in frames:
+        for _rep in range(2):
+            page._handle_scanned_text(frame)
+    assert page.total == len(frames)
+    assert len(page.frames) == len(frames)
+    assert page.review_btn.isEnabled()
+
+    # With all frames stored, the loop auto-finishes exactly once.
+    _app.processEvents()
+    assert reviewed == [True]
+    # The camera loop was stopped before handing over to the review step.
+    assert not page._scanning
+    assert not page._scan_timer.isActive()
+    d.close()
+
+
+def test_qr_import_handle_scanned_text_manual_does_not_autofinish():
+    # Without a camera session running, extra frames never auto-proceed.
+    bw = FakeBalWindow()
+    d = dialogs.WillImportDialog(bw, bal_plugin=bw.bal_plugin)
+    page = d.qr_page
+    reviewed = []
+    page._review_and_sign = lambda: reviewed.append(True)  # type: ignore[assignment]
+
+    frames = split_frames(encode_transfer(["A" * 120, "B" * 120]), 150)
+    assert len(frames) > 1
+    assert not page._scanning
+    for frame in frames:
+        for _rep in range(2):
+            page._handle_scanned_text(frame)
+    assert len(page.frames) == len(frames)
+    _app.processEvents()
+    assert reviewed == []
+    d.close()
+
+
+# ------------------------------------------------------------------ #
+# Animated-QR formats (BC-UR v1/v2, BBQR) via the export/import pages
+# ------------------------------------------------------------------ #
+
+def test_export_format_combo_switches_codecs():
+    bw = FakeBalWindow()
+    bw.willitems = _make_willitems(n=6, payload_len=400)
+    d = dialogs.WillExportDialog(bw, bal_plugin=bw.bal_plugin, initial_mode="qr")
+    page = d.qr_page
+    assert page.format == "balqr"
+    assert page.frames[0].startswith("BAL1")
+    assert page.format_combo.count() == 4
+
+    page._on_format_change(1)  # BC-UR v1
+    assert page.format == "ur1"
+    assert page.frames[0].startswith("ur:bytes/")
+    assert page.index == 0
+    assert page.qr_view.text == page.frames[0]
+
+    page._on_format_change(2)  # BC-UR v2
+    assert page.format == "ur2"
+    assert page.frames[0].startswith("ur:bytes/")
+
+    page._on_format_change(3)  # BBQR
+    assert page.format == "bbqr"
+    assert page.frames[0].startswith("B$")
+    d.close()
+
+
+def test_export_animated_format_frames_fit_budget():
+    bw = FakeBalWindow()
+    bw.willitems = _make_willitems(n=6, payload_len=400)
+    d = dialogs.WillExportDialog(bw, bal_plugin=bw.bal_plugin, initial_mode="qr")
+    page = d.qr_page
+    for index in range(1, 4):
+        page._on_format_change(index)
+        for frame in page.frames:
+            assert len(frame) <= dialogs.CHUNK_PRESETS[0][1]
+    d.close()
+
+
+def _import_roundtrip_fmt(fmt_index):
+    bw = FakeBalWindow()
+    bw.willitems = _make_willitems(2)
+    d = dialogs.WillExportDialog(bw, bal_plugin=bw.bal_plugin, initial_mode="qr")
+    page = d.qr_page
+    page._on_format_change(fmt_index)
+    frames = list(page.frames)
+    assert frames
+    d.close()
+
+    impl = dialogs.WillImportDialog(bw, bal_plugin=bw.bal_plugin)
+    import_page = impl.qr_page
+    caught = {}
+    import_page._finish_import = lambda payload: caught.__setitem__("payload", payload)
+    for frame in frames:
+        import_page._add_frame(frame)
+    assert import_page.review_btn.isEnabled()
+    import_page._review_and_sign()
+    kind, data = dialogs.decode_will_payload(caught["payload"])
+    assert kind == "will"
+    assert set(data) == {"item0", "item1"}
+    impl.close()
+
+
+def test_import_ur1_roundtrip():
+    _import_roundtrip_fmt(1)
+
+
+def test_import_ur2_roundtrip():
+    _import_roundtrip_fmt(2)
+
+
+def test_import_bbqr_roundtrip():
+    _import_roundtrip_fmt(3)
+
+
+def test_import_animated_scan_debounce_autofinish():
+    bw = FakeBalWindow()
+    bw.willitems = _make_willitems(2)
+    d = dialogs.WillExportDialog(bw, bal_plugin=bw.bal_plugin, initial_mode="qr")
+    page = d.qr_page
+    page._on_format_change(2)  # BC-UR v2 fountain
+    frames = list(page.frames)
+    d.close()
+
+    impl = dialogs.WillImportDialog(bw, bal_plugin=bw.bal_plugin)
+    import_page = impl.qr_page
+    reviewed = []
+    import_page._review_and_sign = lambda: reviewed.append(True)  # type: ignore[assignment]
+    import_page._scanning = True
+    for frame in frames:
+        for _rep in range(2):
+            import_page._handle_scanned_text(frame)
+    assert import_page.review_btn.isEnabled()
+    # The fountain transfer's part count is ``len(frames) // 2`` (pure + one
+    # redundant mixed wave).
+    assert import_page.total == len(frames) // 2
+    assert len(import_page.frames) >= import_page.total
+    assert import_page.review_btn.isEnabled()
+    _app.processEvents()
+    assert reviewed == [True]
+    assert not import_page._scanning
+    impl.close()
+
+
+def test_import_garbage_scan_is_ignored():
+    bw = FakeBalWindow()
+    d = dialogs.WillImportDialog(bw, bal_plugin=bw.bal_plugin)
+    page = d.qr_page
+    for garbage in ("hello world", "12345", "B$ZZ", ""):
+        page._handle_scanned_text(garbage)
+        assert not page.frames
+        assert page.total == 0
+        assert not page.review_btn.isEnabled()
+    d.close()
+
+
+def test_import_different_animated_transfer_resets():
+    bw = FakeBalWindow()
+    d = dialogs.WillImportDialog(bw, bal_plugin=bw.bal_plugin)
+    page = d.qr_page
+    warnings = []
+    page.show_warning = lambda msg: warnings.append(msg)  # type: ignore[assignment]
+
+    frames_a = split_frames(encode_transfer(["A" * 120, "B" * 120]), 150)
+    frames_b = split_frames(encode_transfer(["A" * 120, "B" * 120, "C" * 120]), 150)
+    for frame in frames_a:
+        page._add_frame(frame)
+    assert page.total == len(frames_a)
+    assert not warnings
+
+    page._add_frame(frames_b[0])
+    assert warnings
+    assert page.total == 0
+    assert not page.frames
+    assert not page.review_btn.isEnabled()
+    d.close()
+
+
+def test_import_start_stop_scan_signal_wiring():
+    """Regression: _start_scan/_stop_scan must use the QVideoSink signal
+    videoFrameChanged, not the videoFrame frame getter.
+
+    On PyQt6, ``QVideoSink.videoFrame`` is a method (the frame getter), so
+    ``.videoFrame.connect(...)`` raises AttributeError. This test drives the
+    real sink life-cycle with a mocked camera and asserts the scan session
+    starts/ends cleanly with no error.
+    """
+    from PyQt6.QtMultimedia import QCamera, QMediaCaptureSession, QMediaDevices
+
+    bw = FakeBalWindow()
+    d = dialogs.WillImportDialog(bw, bal_plugin=bw.bal_plugin)
+    page = d.qr_page
+    errors = []
+    page.show_error = lambda msg: errors.append(msg)  # type: ignore[assignment]
+
+    fake_device = MagicMock()
+    fake_device.isNull.return_value = False
+
+    with (
+        patch.object(QMediaDevices, "defaultVideoInput", return_value=fake_device),
+        # Mock camera + capture session; the QVideoSink stays real so the
+        # videoFrameChanged connect/disconnect wiring is exercised for real.
+        patch.object(QCamera, "__new__", return_value=MagicMock()),
+        patch.object(QMediaCaptureSession, "__new__", return_value=MagicMock()),
+    ):
+        page._start_scan()
+        assert page._scanning is True
+        assert not errors
+
+        page._stop_scan()
+    assert page._scanning is False
+    assert page._camera is None
+    assert page._video_sink is None
+    assert not errors
+    d.close()
+
+
+# ------------------------------------------------------------------ #
+# Main
+# ------------------------------------------------------------------ #
+
+if __name__ == "__main__":
+    for name in sorted(dir()):
+        if name.startswith("test_"):
+            globals()[name]()
+            print(f"  [OK] {name}")
+    print("[OK] All QR transfer GUI tests passed")