Add script to test Ninja's output

First test checks for #1214.

.travis.yml

@@ -3,4 +3,9 @@ language: cpp
 compiler:
   - gcc
   - clang
-script: ./configure.py --bootstrap && ./ninja all && ./ninja_test --gtest_filter=-SubprocessTest.SetWithLots && ./misc/ninja_syntax_test.py
+script:
+  - ./configure.py --bootstrap
+  - ./ninja all
+  - ./ninja_test --gtest_filter=-SubprocessTest.SetWithLots
+  - ./misc/ninja_syntax_test.py
+  - ./misc/output_test.py

misc/output_test.py

@@ -0,0 +1,61 @@
+#!/usr/bin/env python3
+
+"""Runs ./ninja and checks if the output is correct.
+
+In order to simulate a smart terminal it uses the 'script' command.
+"""
+
+import subprocess
+import sys
+import tempfile
+import unittest
+
+def run(build_ninja, flags='', pipe=False):
+    with tempfile.NamedTemporaryFile('w') as f:
+        f.write(build_ninja)
+        f.flush()
+        ninja_cmd = './ninja {} -f {}'.format(flags, f.name)
+        try:
+            if pipe:
+                output = subprocess.check_output([ninja_cmd], shell=True)
+            else:
+                output = subprocess.check_output(['script', '-qfec', ninja_cmd, '/dev/null'])
+        except subprocess.CalledProcessError as err:
+            sys.stdout.buffer.write(err.output)
+            raise err
+    final_output = ''
+    for line in output.decode('utf-8').splitlines(True):
+        if len(line) > 0 and line[-1] == '\r':
+            continue
+        final_output += line.replace('\r', '')
+    return final_output
+
+class Output(unittest.TestCase):
+    def test_issue_1214(self):
+        print_red = '''rule echo
+  command = printf '\x1b[31mred\x1b[0m'
+  description = echo $out
+
+build a: echo
+'''
+        # Only strip color when ninja's output is piped.
+        self.assertEqual(run(print_red),
+'''[1/1] echo a\x1b[K
+\x1b[31mred\x1b[0m
+''')
+        self.assertEqual(run(print_red, pipe=True),
+'''[1/1] echo a
+red
+''')
+        # Even in verbose mode, colors should still only be stripped when piped.
+        self.assertEqual(run(print_red, flags='-v'),
+'''[1/1] printf '\x1b[31mred\x1b[0m'
+\x1b[31mred\x1b[0m
+''')
+        self.assertEqual(run(print_red, flags='-v', pipe=True),
+'''[1/1] printf '\x1b[31mred\x1b[0m'
+red
+''')
+
+if __name__ == '__main__':
+    unittest.main()