gh-100226: Clarify StreamReader.read behavior

Doc/library/asyncio-stream.rst

@@ -206,12 +206,21 @@ StreamReader
 
    .. coroutinemethod:: read(n=-1)
 
-      Read up to *n* bytes.  If *n* is not provided, or set to ``-1``,
-      read until EOF and return all read bytes.
+      Read up to *n* bytes from the stream.
 
+      If *n* is not provided, or set to ``-1``,
+      read until EOF, then return all read :class:`bytes`.
       If EOF was received and the internal buffer is empty,
       return an empty ``bytes`` object.
 
+      If *n* is ``0``, return an empty ``bytes`` object immediately.
+
+      If *n* is positive, wait for at least 1 byte to become available
+      (or EOF), then return the available ``bytes`` which might be less
+      than *n*.
+      If EOF is received before any byte is read, return an empty
+      ``bytes`` object.
+
    .. coroutinemethod:: readline()
 
       Read one line, where "line" is a sequence of bytes

Lib/asyncio/streams.py

@@ -655,9 +655,9 @@ async def read(self, n=-1):
 
         If n is zero, return empty bytes object immediately.
 
-        If n is positive, this function try to read `n` bytes, and may return
+        If n is positive, this function tries to read `n` bytes, and may return
         less or equal bytes than requested, but at least one byte. If EOF was
-        received before any byte is read, this function returns empty byte
+        received before any byte is read, this function returns an empty bytes
         object.
 
         Returned value is not limited with limit, configured at stream