🧪 Add comprehensive tests for async_.generator

Added tests to `tests/unit/test_async/test_generator.py` to cover:
- Generator correctly closing when an exception is raised inside the context manager
- Exception propagation when the generator itself raises an error
- Proper handling of positional and keyword arguments passed to the wrapped generator

Co-authored-by: rnovatorov <20299819+rnovatorov@users.noreply.github.com>

Author: google-labs-jules[bot]

tests/unit/test_async/test_generator.py

@@ -16,3 +16,46 @@ async def agen():
 
     with pytest.raises(StopAsyncIteration):
         await g.__anext__()
+
+
+async def test_generator_closes_on_exception_in_context() -> None:
+    closed = False
+
+    @enapter.async_.generator
+    async def agen():
+        nonlocal closed
+        try:
+            yield 1
+            yield 2  # pragma: no cover
+        finally:
+            closed = True
+
+    with pytest.raises(ValueError, match="Test error"):
+        async with agen() as g:
+            assert await g.__anext__() == 1
+            raise ValueError("Test error")
+
+    assert closed
+
+
+async def test_generator_raises_exception() -> None:
+    @enapter.async_.generator
+    async def agen():
+        yield 1
+        raise ValueError("Generator error")
+
+    async with agen() as g:
+        assert await g.__anext__() == 1
+        with pytest.raises(ValueError, match="Generator error"):
+            await g.__anext__()
+
+
+async def test_generator_with_args() -> None:
+    @enapter.async_.generator
+    async def agen(a: int, b: int = 0):
+        yield a
+        yield b
+
+    async with agen(10, b=20) as g:
+        assert await g.__anext__() == 10
+        assert await g.__anext__() == 20