first commit

myenv/Lib/site-packages/trio/_tests/test_contextvars.py

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+from __future__ import annotations
+
+import contextvars
+
+from .. import _core
+
+trio_testing_contextvar: contextvars.ContextVar[str] = contextvars.ContextVar(
+    "trio_testing_contextvar",
+)
+
+
+async def test_contextvars_default() -> None:
+    trio_testing_contextvar.set("main")
+    record: list[str] = []
+
+    async def child() -> None:
+        value = trio_testing_contextvar.get()
+        record.append(value)
+
+    async with _core.open_nursery() as nursery:
+        nursery.start_soon(child)
+    assert record == ["main"]
+
+
+async def test_contextvars_set() -> None:
+    trio_testing_contextvar.set("main")
+    record: list[str] = []
+
+    async def child() -> None:
+        trio_testing_contextvar.set("child")
+        value = trio_testing_contextvar.get()
+        record.append(value)
+
+    async with _core.open_nursery() as nursery:
+        nursery.start_soon(child)
+    value = trio_testing_contextvar.get()
+    assert record == ["child"]
+    assert value == "main"
+
+
+async def test_contextvars_copy() -> None:
+    trio_testing_contextvar.set("main")
+    context = contextvars.copy_context()
+    trio_testing_contextvar.set("second_main")
+    record: list[str] = []
+
+    async def child() -> None:
+        value = trio_testing_contextvar.get()
+        record.append(value)
+
+    async with _core.open_nursery() as nursery:
+        context.run(nursery.start_soon, child)
+        nursery.start_soon(child)
+    value = trio_testing_contextvar.get()
+    assert set(record) == {"main", "second_main"}
+    assert value == "second_main"