pythonnative/src/pythonnative/testing/backend.py at v0.43.1 · pythonnative/pythonnative · GitHub

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"""In-memory backend implementing the batched mutation protocol.

[`FakeBackend`][pythonnative.testing.FakeBackend] speaks the same

protocol as the platform registries (``apply_mutations``,

``resolve_view``, ``measure_intrinsic``, ``command``, plus the animation

hooks) while keeping a real tree of

[`FakeView`][pythonnative.testing.FakeView] objects, so tests can assert

on structure, props, and frames without a device.

The fake raises on malformed transactions, including unknown tags, double

destroys, and insertion into a destroyed parent. Production bridge renderers

validate versioned commits before mutation and fail the surface on rejection.

Recorded op shapes (in ``FakeBackend.ops``):

- ``("create", type_name, view.id)``

- ``("update", type_name, view.id, tuple(sorted(changed_keys)))``

- ``("insert_child", parent.id, child.id, index)``

- ``("destroy", view.id)``

- ``("set_frame", view.id, x, y, w, h)``

"""

from __future__ import annotations

from typing import Any, Dict, Iterator, List, Optional, Sequence, Tuple

from ..mutations import CreateOp, DestroyOp, InsertOp, Mutation, SetFrameOp, UpdateOp

__all__ = ["DEFAULT_INTRINSIC", "FakeBackend", "FakeView"]

DEFAULT_INTRINSIC: Dict[str, Tuple[float, float]] = {

"Text": (60.0, 16.0),

"Button": (80.0, 32.0),

"Image": (40.0, 40.0),

"TextInput": (120.0, 32.0),

"TabBar": (320.0, 49.0),

}

"""Intrinsic sizes reported for content-sized leaves (what platform measure hooks would return)."""

class FakeView:

"""Simulated native view: type, props, children, and last frame.

Attributes:

tag: The reconciler-assigned tag (use with ``fire`` / events).

type_name: Native type, e.g. ``"Text"``.

props: Native-safe props (event callbacks are stripped; they

live in the event registry keyed by ``tag``).

children: Child views in order.

frame: ``(x, y, width, height)`` from the last layout pass.

"""

_next_id = 0

def __init__(self, tag: int, type_name: str, props: Dict[str, Any]) -> None:

FakeView._next_id += 1

self.id = FakeView._next_id

self.tag = tag

self.type_name = type_name

self.props: Dict[str, Any] = dict(props)

self.children: List[FakeView] = []

self.parent: Optional[FakeView] = None

self.frame: Tuple[float, float, float, float] = (0.0, 0.0, 0.0, 0.0)

self.destroyed = False

def __repr__(self) -> str:

label = self.text

suffix = f" {label!r}" if label else ""

return f"<{self.type_name} tag={self.tag}{suffix}>"

# -- content --------------------------------------------------------

@property

def text(self) -> Optional[str]:

"""Visible text for text-bearing views (``Text.text``, ``Button.title``, ``TextInput.value``)."""

for key in ("text", "title", "value", "placeholder"):

value = self.props.get(key)

if isinstance(value, str):

return value

return None

@property

def hidden(self) -> bool:

"""Whether this view is removed from layout (``display: "none"``)."""

return self.props.get("display") == "none" or self.type_name == "Screen" and self.props.get("active") is False

@property

def test_id(self) -> Optional[str]:

"""The ``test_id`` prop, if set."""

return self.props.get("test_id")

@property

def label(self) -> Optional[str]:

"""The ``accessibility_label`` prop, if set."""

return self.props.get("accessibility_label")

# -- traversal ------------------------------------------------------

def walk(self, *, include_hidden: bool = True) -> Iterator["FakeView"]:

"""Yield this view and every descendant, depth-first.

With ``include_hidden=False`` subtrees under a ``display: "none"``

view are skipped (what a user can see).

"""

if not include_hidden and self.hidden:

return

yield self

for child in self.children:

yield from child.walk(include_hidden=include_hidden)

def find_all(self, predicate_or_type: Any) -> List["FakeView"]:

"""Every view in this subtree matching a type name or predicate."""

if isinstance(predicate_or_type, str):

wanted = predicate_or_type

def predicate(v: "FakeView") -> bool:

return v.type_name == wanted

else:

predicate = predicate_or_type

return [v for v in self.walk() if predicate(v)]

def find_first(self, predicate_or_type: Any) -> Optional["FakeView"]:

"""Return the first view in this subtree matching a type name or predicate, or ``None``."""

found = self.find_all(predicate_or_type)

return found[0] if found else None

def dump(self, indent: int = 0) -> str:

"""Indented, human-readable subtree (for failing-test output)."""

line = " " * indent + repr(self)

x, y, w, h = self.frame

if w or h:

line += f" @({x:g},{y:g} {w:g}x{h:g})"

return "\n".join([line, *(c.dump(indent + 2) for c in self.children)])

class FakeBackend:

"""Tag-table backend recording one tuple per applied mutation.

Args:

intrinsic: Override the intrinsic sizes used by

``measure_intrinsic`` (defaults to

[`DEFAULT_INTRINSIC`][pythonnative.testing.backend.DEFAULT_INTRINSIC]).

"""

def __init__(self, intrinsic: Optional[Dict[str, Tuple[float, float]]] = None) -> None:

self.intrinsic = dict(DEFAULT_INTRINSIC if intrinsic is None else intrinsic)

self.views: Dict[int, FakeView] = {}

self.ops: List[Any] = []

self.batches: List[List[Any]] = []

self.measure_calls: List[int] = []

self.commands: List[Tuple[int, str, Dict[str, Any]]] = []

self.animated: List[Tuple[int, str, Any]] = []

self.last_create_props: Dict[str, Any] = {}

self.last_update_changes: Dict[str, Any] = {}

# ------------------------------------------------------------------

# Commit channel

# ------------------------------------------------------------------

def apply_mutations(self, ops: Sequence[Mutation]) -> None:

"""Apply one committed batch to the view tree, recording each op in ``ops`` and ``batches``.

Raises ``AssertionError`` on malformed transactions (unknown tags, double creates or destroys).

"""

batch: List[Any] = []

for op in ops:

recorded = self._apply_one(op)

self.ops.append(recorded)

batch.append(recorded)

self.batches.append(batch)

def _apply_one(self, op: Mutation) -> Tuple[Any, ...]:

if isinstance(op, CreateOp):

if op.tag in self.views:

raise AssertionError(f"create: tag {op.tag} already registered")

view = FakeView(op.tag, op.type_name, op.props)

self.views[op.tag] = view

self.last_create_props = dict(op.props)

return ("create", op.type_name, view.id)

if isinstance(op, UpdateOp):

view = self._require(op.tag, "update")

view.props.update(op.changed_props)

self.last_update_changes = dict(op.changed_props)

return ("update", view.type_name, view.id, tuple(sorted(op.changed_props)))

if isinstance(op, InsertOp):

parent = self._require(op.parent_tag, "insert_child")

child = self._require(op.child_tag, "insert_child")

if child.parent is not None:

child.parent.children.remove(child)

child.parent = None

index = max(0, min(op.index, len(parent.children)))

parent.children.insert(index, child)

child.parent = parent

return ("insert_child", parent.id, child.id, index)

if isinstance(op, DestroyOp):

view = self.views.pop(op.tag, None)

if view is None:

raise AssertionError(f"destroy: unknown tag {op.tag}")

if view.parent is not None:

view.parent.children.remove(view)

view.parent = None

view.destroyed = True

return ("destroy", view.id)

if isinstance(op, SetFrameOp):

view = self._require(op.tag, "set_frame")

view.frame = (op.x, op.y, op.width, op.height)

return ("set_frame", view.id, op.x, op.y, op.width, op.height)

raise AssertionError(f"unknown mutation op: {op!r}")

def _require(self, tag: int, op_name: str) -> FakeView:

view = self.views.get(tag)

if view is None:

raise AssertionError(f"{op_name}: unknown tag {tag}")

return view

# ------------------------------------------------------------------

# Imperative escape hatches

# ------------------------------------------------------------------

def resolve_view(self, tag: int) -> Optional[FakeView]:

"""Return the live view registered under ``tag``, or ``None``."""

return self.views.get(tag)

def measure_intrinsic(self, tag: int, max_width: float, max_height: float) -> Tuple[float, float]:

"""Return the configured intrinsic size for the view's type and record the call in ``measure_calls``.

Unknown tags and types without an entry measure as ``(0.0, 0.0)``; the constraints are ignored.

"""

view = self.views.get(tag)

if view is None:

return (0.0, 0.0)

self.measure_calls.append(view.id)

return self.intrinsic.get(view.type_name, (0.0, 0.0))

def command(self, tag: int, name: str, args: Optional[Dict[str, Any]] = None) -> Any:

"""Record an imperative view command in ``commands`` and return ``None``."""

self.commands.append((tag, name, dict(args or {})))

view = self.views.get(tag)

if view is not None and view.type_name == "VirtualList":

arguments = args or {}

if name == "scroll_to_index":

self.request_list(tag, int(arguments["index"]))

elif name == "scroll_to_end":

self.request_list(tag, max(0, len(view.props["keys"]) - 1))

return None

def request_list(self, tag: int, first: int, *, extent: float = 800.0) -> None:

"""Simulate a native viewport using the shared list request protocol."""

from ..events import dispatch_event

view = self._require(tag, "request_list")

if view.type_name != "VirtualList":

raise TypeError("request_list requires a VirtualList tag")

keys = view.props["keys"]

heights = view.props["row_heights"]

first = max(0, min(first, len(keys) - 1))

last, covered = first, 0.0

while last < len(keys) and covered < extent:

covered += heights[last]

last += 1

offset = sum(heights[:first])

dispatch_event(

tag,

"on_scroll",

{

"first": first,

"last": last - 1,

"extent": extent,

"range": sum(heights),

"x": offset if view.props.get("horizontal") else 0,

"y": 0 if view.props.get("horizontal") else offset,

)

if keys:

dispatch_event(

tag,

"on_bind_row",

{

"key": keys[first],

"index": first,

"revision": view.props["revision"],

"extent": extent,

"width": view.frame[2],

)

def set_animated_property(self, tag: int, prop_name: str, value: Any) -> None:

"""Record an animated property write in ``animated`` without touching ``props``."""

self.animated.append((tag, prop_name, value))

def start_animation(self, tag: int, anim_id: int, prop_name: str, spec: Dict[str, Any]) -> bool:

"""Decline native animation (return ``False``) so animations run through the Python driver."""

return False

def cancel_animation(self, tag: int, anim_id: int) -> Any:

"""Do nothing; the fake never starts native animations."""

return None

# ------------------------------------------------------------------

# Diagnostics

# ------------------------------------------------------------------

def live_view_count(self) -> int:

"""Return how many views are currently registered (created and not yet destroyed)."""

return len(self.views)

def ops_of(self, kind: str) -> List[Any]:

"""Every recorded op tuple whose first element is ``kind``."""

return [op for op in self.ops if op[0] == kind]

def detached_views(self, type_name: Optional[str] = None) -> List[FakeView]:

"""Live views never inserted into a parent (``Portal`` overlays, the root)."""

out = [v for v in self.views.values() if v.parent is None]

if type_name is not None:

out = [v for v in out if v.type_name == type_name]

return out

pythonnative/src/pythonnative/testing/backend.py at v0.43.1 · pythonnative/pythonnative · GitHub

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