Ignore redirected stdout with --output, -o

This makes it easier to use HTTPie in cron jobs and scripts.

Closes #259

CHANGELOG.rst

@@ -5,6 +5,7 @@ Change Log
 This document records all notable changes to `HTTPie <http://httpie.org>`_.
 This project adheres to `Semantic Versioning <http://semver.org/>`_.
 
+
 `1.0.0-dev`_ (Unreleased)
 -------------------------
 
@@ -15,6 +16,8 @@ This project adheres to `Semantic Versioning <http://semver.org/>`_.
 * Added ``-F`` as short name for ``--follow``
 * Added JSON detection when ``--json, -j`` is used in order to correctly format
   JSON responses even when an incorrect ``Content-Type`` is returned.
+* Redirected ``stdout`` doesn't trigger an error anymore when ``--output FILE``
+  is set.
 * Changed the default color style back to ``solarized`` as it supports
   both the light and dark terminal background mode
 * Fixed ``--session`` when used with ``--download``
@@ -22,7 +25,7 @@ This project adheres to `Semantic Versioning <http://semver.org/>`_.
 
 
 `0.9.3`_ (2016-01-01)
--------------------------
+---------------------
 
 * Changed the default color ``--style`` from ``solarized`` to ``monokai``
 * Added basic Bash autocomplete support (need to be installed manually)

Makefile

@@ -11,7 +11,7 @@ END=" \#\#\# \033[0m\n"
 all: test
 
 
-init:
+init: uninstall-httpie
 	@echo $(TAG)Installing dev requirements$(END)
 	pip install --upgrade -r $(REQUIREMENTS)
 

httpie/cli.py

@@ -310,8 +310,9 @@ output_options.add_argument(
     dest='output_file',
     metavar='FILE',
     help="""
-    Save output to FILE. If --download is set, then only the response body is
+    Save output to FILE instead of stdout. If --download is also set, then only
-    saved to the file. Other parts of the HTTP exchange are printed to stderr.
+    the response body is saved to FILE. Other parts of the HTTP exchange are
+    printed to stderr.
 
     """
 

httpie/core.py

@@ -204,4 +204,8 @@ def main(args=sys.argv[1:], env=Environment(), error=None):
         if downloader and not downloader.finished:
             downloader.failed()
 
+        if (not isinstance(args, list) and args.output_file and
+                args.output_file_specified):
+            args.output_file.close()
+
     return exit_status

httpie/input.py

@@ -171,12 +171,10 @@ class HTTPieArgumentParser(ArgumentParser):
         Modify `env.stdout` and `env.stdout_isatty` based on args, if needed.
 
         """
-        if not self.env.stdout_isatty and self.args.output_file:
+        self.args.output_file_specified = bool(self.args.output_file)
-            self.error('Cannot use --output, -o with redirected output.')
-
         if self.args.download:
             # FIXME: Come up with a cleaner solution.
-            if not self.env.stdout_isatty:
+            if not self.args.output_file and not self.env.stdout_isatty:
                 # Use stdout as the download output file.
                 self.args.output_file = self.env.stdout
             # With `--download`, we write everything that would normally go to

tests/test_output.py

@@ -1,10 +1,30 @@
+import os
+from tempfile import gettempdir
+
 import pytest
 
 from utils import TestEnvironment, http, HTTP_OK, COLOR, CRLF
 from httpie import ExitStatus
+from httpie.compat import urlopen
 from httpie.output.formatters.colors import get_lexer
 
 
+@pytest.mark.parametrize('stdout_isatty', [(True,), (False,)])
+def test_output_option(httpbin, stdout_isatty):
+    output_filename = os.path.join(gettempdir(), test_output_option.__name__)
+    url = httpbin + '/robots.txt'
+
+    r = http('--output', output_filename, url,
+             env=TestEnvironment(stdout_isatty=stdout_isatty))
+    assert r == ''
+
+    expected_body = urlopen(url).read().decode()
+    with open(output_filename, 'r') as f:
+        actual_body = f.read()
+
+    assert actual_body == expected_body
+
+
 class TestVerboseFlag:
     def test_verbose(self, httpbin):
         r = http('--verbose',

tests/test_windows.py

@@ -22,7 +22,9 @@ class TestFakeWindows:
     def test_output_file_pretty_not_allowed_on_windows(self, httpbin):
         env = TestEnvironment(is_windows=True)
         output_file = os.path.join(
-            tempfile.gettempdir(), '__httpie_test_output__')
+            tempfile.gettempdir(),
+            self.test_output_file_pretty_not_allowed_on_windows.__name__
+        )
         r = http('--output', output_file,
                  '--pretty=all', 'GET', httpbin.url + '/get',
                  env=env, error_exit_ok=True)