From 571295d090d1eec40b45a88c2c5f54ceaf3c4e15 Mon Sep 17 00:00:00 2001
From: Damien George <damien.p.george@gmail.com>
Date: Mon, 30 Jul 2018 12:05:48 +1000
Subject: [PATCH] tests/extmod/ujson_dump_iobase.py: Return number of bytes
 written.

Otherwise returning None indicates that the write would block and nothing
was actually written.  Fixes issue #3990.
---
 tests/extmod/ujson_dump_iobase.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/extmod/ujson_dump_iobase.py b/tests/extmod/ujson_dump_iobase.py
index d30d1b561e..51d507cd1a 100644
--- a/tests/extmod/ujson_dump_iobase.py
+++ b/tests/extmod/ujson_dump_iobase.py
@@ -24,6 +24,7 @@ class S(io.IOBase):
             # uPy passes a bytearray, CPython passes a str
             buf = str(buf, 'ascii')
         self.buf += buf
+        return len(buf)
 
 
 # dump to the user stream