diff --git a/tests/test_shm.py b/tests/test_shm.py
new file mode 100644
index 0000000..83ce7e2
--- /dev/null
+++ b/tests/test_shm.py
@@ -0,0 +1,84 @@
+"""
+Shared mem primitives and APIs.
+
+"""
+
+# import numpy
+import pytest
+import trio
+import tractor
+from tractor._shm import (
+    open_shm_list,
+    attach_shm_list,
+)
+
+
+@tractor.context
+async def child_read_shm_list(
+    ctx: tractor.Context,
+    shm_key: str,
+    use_str: bool,
+) -> None:
+
+    shml = attach_shm_list(key=shm_key)
+    await ctx.started(shml.key)
+
+    async with ctx.open_stream() as stream:
+        async for i in stream:
+            print(f'reading shm list index: {i}')
+
+            if use_str:
+                expect = str(float(i))
+            else:
+                expect = float(i)
+
+            assert expect == shml[i]
+
+
+@pytest.mark.parametrize(
+    'use_str', [False, True],
+)
+def test_parent_writer_child_reader(
+    use_str: bool,
+):
+
+    async def main():
+        async with tractor.open_nursery() as an:
+
+            # allocate writeable list in parent
+            key = 'shm_list'
+            shml = open_shm_list(
+                key=key,
+                readonly=False,
+            )
+
+            portal = await an.start_actor(
+                'shm_reader',
+                enable_modules=[__name__],
+            )
+
+            async with (
+                portal.open_context(
+                    child_read_shm_list,  # taken from pytest parameterization
+                    shm_key=key,
+                    use_str=use_str,
+                ) as (ctx, sent),
+
+                ctx.open_stream() as stream,
+            ):
+
+                assert sent == key
+
+                for i in range(2 ** 10):
+
+                    val = float(i)
+                    if use_str:
+                        val = str(val)
+
+                    print(f'writing {val}')
+                    shml[i] = val
+                    await stream.send(i)
+
+            await portal.cancel_actor()
+
+    trio.run(main)