1 files changed, 30 insertions, 0 deletions
diff --git a/tests/extmod/json_dump_iobase.py b/tests/extmod/json_dump_iobase.py
new file mode 100644
index 000000000..94d317b87
--- /dev/null
+++ b/tests/extmod/json_dump_iobase.py
@@ -0,0 +1,30 @@
+# test json.dump in combination with io.IOBase
+
+try:
+    import io, json
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+if not hasattr(io, "IOBase"):
+    print("SKIP")
+    raise SystemExit
+
+
+# a user stream that only has the write method
+class S(io.IOBase):
+    def __init__(self):
+        self.buf = ""
+
+    def write(self, buf):
+        if type(buf) == bytearray:
+            # uPy passes a bytearray, CPython passes a str
+            buf = str(buf, "ascii")
+        self.buf += buf
+        return len(buf)
+
+
+# dump to the user stream
+s = S()
+json.dump([123, {}], s)
+print(s.buf)