From 12250ec3edf4e91fe2ef98556dd27f65012db524 Mon Sep 17 00:00:00 2001
From: andri lim <jangko128@gmail.com>
Date: Tue, 3 Sep 2019 14:16:42 +0700
Subject: [PATCH] fixes zero length input bug in output_stream.append

---
 faststreams/output_stream.nim | 1 +
 tests/test_output_stream.nim  | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/faststreams/output_stream.nim b/faststreams/output_stream.nim
index a3193fb..5fd8dae 100644
--- a/faststreams/output_stream.nim
+++ b/faststreams/output_stream.nim
@@ -356,6 +356,7 @@ proc append*(c: var WriteCursor, bytes: openarray[byte]) {.inline.} =
     pageRemaining = c.runway
     inputLen = bytes.len
 
+  if inputLen == 0: return
   if inputLen <= pageRemaining:
     copyMem(c.head, unsafeAddr bytes[0], inputLen)
     c.head = shift(c.head, inputLen)
diff --git a/tests/test_output_stream.nim b/tests/test_output_stream.nim
index 26f02f1..90f17a2 100644
--- a/tests/test_output_stream.nim
+++ b/tests/test_output_stream.nim
@@ -55,6 +55,10 @@ suite "output stream":
   test "no appends produce an empty output":
     checkOutputsMatch()
 
+  test "append zero length slice":
+    output ""
+    checkOutputsMatch()
+  
   test "string output":
     for i in 0 .. 1:
       output $i