3 files changed, 90 insertions, 0 deletions
diff --git a/extmod/uasyncio/stream.py b/extmod/uasyncio/stream.py
index 2a1efd1a1..b6d787e4f 100644
--- a/extmod/uasyncio/stream.py
+++ b/extmod/uasyncio/stream.py
@@ -30,6 +30,18 @@ class Stream:
         yield core._io_queue.queue_read(self.s)
         return self.s.read(n)
 
+    async def readexactly(self, n):
+        r = b""
+        while n:
+            yield core._io_queue.queue_read(self.s)
+            r2 = self.s.read(n)
+            if r2 is not None:
+                if not len(r2):
+                    raise EOFError
+                r += r2
+                n -= len(r2)
+        return r
+
     async def readline(self):
         l = b""
         while True:
diff --git a/tests/multi_net/uasyncio_tcp_readexactly.py b/tests/multi_net/uasyncio_tcp_readexactly.py
new file mode 100644
index 000000000..71d8c6d0e
--- /dev/null
+++ b/tests/multi_net/uasyncio_tcp_readexactly.py
@@ -0,0 +1,68 @@
+# Test uasyncio stream readexactly() method using TCP server/client
+
+try:
+    import uasyncio as asyncio
+except ImportError:
+    try:
+        import asyncio
+    except ImportError:
+        print("SKIP")
+        raise SystemExit
+
+PORT = 8000
+
+
+async def handle_connection(reader, writer):
+    writer.write(b"a")
+    await writer.drain()
+
+    # Split the first 2 bytes up so the client must wait for the second one
+    await asyncio.sleep(0.1)
+
+    writer.write(b"b")
+    await writer.drain()
+
+    writer.write(b"c")
+    await writer.drain()
+
+    writer.write(b"d")
+    await writer.drain()
+
+    print("close")
+    writer.close()
+    await writer.wait_closed()
+
+    print("done")
+    ev.set()
+
+
+async def tcp_server():
+    global ev
+    ev = asyncio.Event()
+    server = await asyncio.start_server(handle_connection, "0.0.0.0", PORT)
+    print("server running")
+    multitest.next()
+    async with server:
+        await asyncio.wait_for(ev.wait(), 10)
+
+
+async def tcp_client():
+    reader, writer = await asyncio.open_connection(IP, PORT)
+    print(await reader.readexactly(2))
+    print(await reader.readexactly(0))
+    print(await reader.readexactly(1))
+    try:
+        print(await reader.readexactly(2))
+    except EOFError as er:
+        print("EOFError")
+    print(await reader.readexactly(0))
+
+
+def instance0():
+    multitest.globals(IP=multitest.get_network_ip())
+    asyncio.run(tcp_server())
+
+
+def instance1():
+    multitest.next()
+    asyncio.run(tcp_client())
diff --git a/tests/multi_net/uasyncio_tcp_readexactly.py.exp b/tests/multi_net/uasyncio_tcp_readexactly.py.exp
new file mode 100644
index 000000000..65ce6d628
--- /dev/null
+++ b/tests/multi_net/uasyncio_tcp_readexactly.py.exp
@@ -0,0 +1,10 @@
+--- instance0 ---
+server running
+close
+done
+--- instance1 ---
+b'ab'
+b''
+b'c'
+EOFError
+b''