From aaec64b6a641a6afb2bdb9060cdff62998029155 Mon Sep 17 00:00:00 2001
From: Tim Holy <tim.holy@gmail.com>
Date: Sun, 21 Aug 2016 06:08:51 -0500
Subject: [PATCH] Add do-block support for redirect_std[out,err]

In particular, these simplify testing for warnings
---
 base/stream.jl            | 28 ++++++++++++++++++++++++++++
 doc/stdlib/io-network.rst | 12 ++++++++++++
 test/show.jl              | 22 +++++++++++++++++++++-
 3 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/base/stream.jl b/base/stream.jl
index d57180fe7badb3..8a3e532875e7ad 100644
--- a/base/stream.jl
+++ b/base/stream.jl
@@ -955,6 +955,34 @@ for (x, writable, unix_fd, c_symbol) in
     end
 end
 
+for (F,S) in ((:redirect_stdout, :STDOUT), (:redirect_stderr, :STDERR))
+    @eval function $F(f::Function, stream)
+        STDOLD = $S
+        local ret
+        $F(stream)
+        try
+            ret = f()
+        finally
+            $F(STDOLD)
+        end
+        ret
+    end
+end
+
+"""
+    redirect_stdout(f::Function, stream)
+
+Run the function `f` while redirecting `STDOUT` to `stream`. Upon completion, `STDOUT` is restored to its prior setting.
+"""
+redirect_stdout(f::Function, stream)
+
+"""
+    redirect_stderr(f::Function, stream)
+
+Run the function `f` while redirecting `STDERR` to `stream`. Upon completion, `STDERR` is restored to its prior setting.
+"""
+redirect_stderr(f::Function, stream)
+
 mark(x::LibuvStream)     = mark(x.buffer)
 unmark(x::LibuvStream)   = unmark(x.buffer)
 reset(x::LibuvStream)    = reset(x.buffer)
diff --git a/doc/stdlib/io-network.rst b/doc/stdlib/io-network.rst
index 67a1b123c57b6a..aeec513c0f45dd 100644
--- a/doc/stdlib/io-network.rst
+++ b/doc/stdlib/io-network.rst
@@ -350,12 +350,24 @@ General I/O
 
    Replace ``STDOUT`` by stream for all C and Julia level output to ``STDOUT``\ . Note that ``stream`` must be a TTY, a ``Pipe`` or a ``TCPSocket``\ .
 
+.. function:: redirect_stdout(f::Function, stream)
+
+   .. Docstring generated from Julia source
+
+   Run the function ``f`` while redirecting ``STDOUT`` to ``stream``\ . Upon completion, ``STDOUT`` is restored to its prior setting.
+
 .. function:: redirect_stderr([stream])
 
    .. Docstring generated from Julia source
 
    Like ``redirect_stdout``\ , but for ``STDERR``\ .
 
+.. function:: redirect_stderr(f::Function, stream)
+
+   .. Docstring generated from Julia source
+
+   Run the function ``f`` while redirecting ``STDERR`` to ``stream``\ . Upon completion, ``STDERR`` is restored to its prior setting.
+
 .. function:: redirect_stdin([stream])
 
    .. Docstring generated from Julia source
diff --git a/test/show.jl b/test/show.jl
index 2d185d76fb3796..3292d31ff169df 100644
--- a/test/show.jl
+++ b/test/show.jl
@@ -318,6 +318,26 @@ let oldout = STDOUT, olderr = STDERR
     end
 end
 
+let filename = tempname()
+    ret = open(filename, "w") do f
+        redirect_stdout(f) do
+            println("hello")
+            [1,3]
+        end
+    end
+    @test ret == [1,3]
+    @test chomp(readstring(filename)) == "hello"
+    ret = open(filename, "w") do f
+        redirect_stderr(f) do
+            warn("hello")
+            [2]
+        end
+    end
+    @test ret == [2]
+    @test contains(readstring(filename), "WARNING: hello")
+    rm(filename)
+end
+
 # issue #12960
 type T12960 end
 let
@@ -576,4 +596,4 @@ end
 # Test compact printing of homogeneous tuples
 @test repr(NTuple{7,Int64}) == "NTuple{7,Int64}"
 @test repr(Tuple{Float64, Float64, Float64, Float64}) == "NTuple{4,Float64}"
-@test repr(Tuple{Float32, Float32, Float32}) == "Tuple{Float32,Float32,Float32}"
\ No newline at end of file
+@test repr(Tuple{Float32, Float32, Float32}) == "Tuple{Float32,Float32,Float32}"