From 404eadfdafec7b74d90190d9b5c67330e9ca1954 Mon Sep 17 00:00:00 2001
From: dkf <donal.k.fellows@manchester.ac.uk>
Date: Sun, 24 Jul 2016 12:45:07 +0000
Subject: Make a few tests more resilient to differences in the semantics of
 pipes between operating systems.

---
 doc/chan.n      | 12 ++++++++++++
 tests/zlib.test | 12 ++++++++----
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/doc/chan.n b/doc/chan.n
index 7ea0d19..cc53d3b 100644
--- a/doc/chan.n
+++ b/doc/chan.n
@@ -547,6 +547,18 @@ this, spawn with "2>@" or
 ">@" redirection operators onto the write side of a pipe, and then
 immediately close it in the parent. This is necessary to get an EOF on
 the read side once the child has exited or otherwise closed its output.
+.RS
+.PP
+Note that the pipe buffering semantics can vary at the operating system level
+substantially; it is not safe to assume that a write performed on the output
+side of the pipe will appear instantly to the input side. This is a
+fundamental difference and Tcl cannot conceal it. The overall stream semantics
+\fIare\fR compatible, so blocking reads and writes will not see most of the
+differences, but the details of what exactly gets written when are not. This
+is most likely to show up when using pipelines for testing; care should be
+taken to ensure that deadlocks do not occur and that potential short reads are
+allowed for.
+.RE
 .VE 8.6
 .TP
 \fBchan pop \fIchannelId\fR
diff --git a/tests/zlib.test b/tests/zlib.test
index c9e5f10..8a040d8 100644
--- a/tests/zlib.test
+++ b/tests/zlib.test
@@ -251,9 +251,10 @@ test zlib-8.8 {transformation and fconfigure} -setup {
 } -constraints zlib -body {
     zlib push compress $outSide -dictionary $spdyDict
     fconfigure $outSide -blocking 0 -translation binary -buffering none
-    fconfigure $inSide -blocking 0 -translation binary
+    fconfigure $inSide -blocking 1 -translation binary
     puts -nonewline $outSide $spdyHeaders
     chan pop $outSide
+    chan close $outSide
     set compressed [read $inSide]
     catch {zlib decompress $compressed} err opt
     list [string length [zlib compress $spdyHeaders]] \
@@ -269,10 +270,11 @@ test zlib-8.9 {transformation and fconfigure} -setup {
 } -constraints zlib -body {
     zlib push compress $outSide -dictionary $spdyDict
     fconfigure $outSide -blocking 0 -translation binary -buffering none
-    fconfigure $inSide -blocking 0 -translation binary
+    fconfigure $inSide -blocking 1 -translation binary
     puts -nonewline $outSide $spdyHeaders
     set result [fconfigure $outSide -checksum]
     chan pop $outSide
+    chan close $outSide
     $strm put -dictionary $spdyDict [read $inSide]
     lappend result [string length $spdyHeaders] [string length [$strm get]]
 } -cleanup {
@@ -285,9 +287,10 @@ test zlib-8.10 {transformation and fconfigure} -setup {
 } -constraints {zlib recentZlib} -body {
     zlib push deflate $outSide -dictionary $spdyDict
     fconfigure $outSide -blocking 0 -translation binary -buffering none
-    fconfigure $inSide -blocking 0 -translation binary
+    fconfigure $inSide -blocking 1 -translation binary
     puts -nonewline $outSide $spdyHeaders
     chan pop $outSide
+    chan close $outSide
     set compressed [read $inSide]
     catch {
 	zlib inflate $compressed
@@ -306,9 +309,10 @@ test zlib-8.11 {transformation and fconfigure} -setup {
 } -constraints zlib -body {
     zlib push deflate $outSide -dictionary $spdyDict
     fconfigure $outSide -blocking 0 -translation binary -buffering none
-    fconfigure $inSide -blocking 0 -translation binary
+    fconfigure $inSide -blocking 1 -translation binary
     puts -nonewline $outSide $spdyHeaders
     chan pop $outSide
+    chan close $outSide
     $strm put -dictionary $spdyDict [read $inSide]
     list [string length $spdyHeaders] [string length [$strm get]]
 } -cleanup {
-- 
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