extmod/uasyncio: Implement stream read(-1) to read all data up to EOF.

Fixes issue #6355.

Signed-off-by: Damien George <damien@micropython.org>

docs/library/uasyncio.rst

@@ -237,9 +237,11 @@ TCP stream connections
 
     This is a coroutine.
 
-.. method:: Stream.read(n)
+.. method:: Stream.read(n=-1)
 
-    Read up to *n* bytes and return them.
+    Read up to *n* bytes and return them.  If *n* is not provided or -1 then read all
+    bytes until EOF.  The returned value will be an empty bytes object if EOF is
+    encountered before any bytes are read.
 
     This is a coroutine.
 

extmod/uasyncio/stream.py

@@ -26,9 +26,17 @@ class Stream:
         # TODO yield?
         self.s.close()
 
-    async def read(self, n):
-        yield core._io_queue.queue_read(self.s)
-        return self.s.read(n)
+    async def read(self, n=-1):
+        r = b""
+        while True:
+            yield core._io_queue.queue_read(self.s)
+            r2 = self.s.read(n)
+            if r2 is not None:
+                if n >= 0:
+                    return r2
+                if not len(r2):
+                    return r
+                r += r2
 
     async def readinto(self, buf):
         yield core._io_queue.queue_read(self.s)

tests/multi_net/uasyncio_tcp_readall.py

@@ -0,0 +1,60 @@
+# Test uasyncio stream read(-1) 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()
+
+    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(), 2)
+
+
+async def tcp_client():
+    reader, writer = await asyncio.open_connection(IP, PORT)
+    print(await reader.read())
+    print(await reader.read())  # should be empty
+    print(await reader.read(1))  # should be empty
+
+
+def instance0():
+    multitest.globals(IP=multitest.get_network_ip())
+    asyncio.run(tcp_server())
+
+
+def instance1():
+    multitest.next()
+    asyncio.run(tcp_client())

tests/multi_net/uasyncio_tcp_readall.py.exp

@@ -0,0 +1,8 @@
+--- instance0 ---
+server running
+close
+done
+--- instance1 ---
+b'abc'
+b''
+b''