standardise program/sox.py formatting, add test case, docstring (#53)

* standardise program/sox.py formatting, add test case
* add program/sox.peak_level() docstring
* update .travis.yml to include sox as a test dependency
* move sox from test dependency to normal dependency
* update README to mention sox, remove small autoconf mention
* use .splitlines() instead of .split('n')

.travis.yml

@@ -6,7 +6,7 @@ install:
     # Dependencies
     - sudo apt-get update -qq
     - sudo pip install --upgrade pip
-    - sudo apt-get install -qq cdparanoia cdrdao gstreamer0.10-plugins-base gstreamer0.10-plugins-good libcdio-dev libiso9660-dev libsndfile1-dev python-cddb python-gobject swig python-dev python-xdg
+    - sudo apt-get install -qq cdparanoia cdrdao gstreamer0.10-plugins-base gstreamer0.10-plugins-good libcdio-dev libiso9660-dev libsndfile1-dev python-cddb python-gobject swig python-dev python-xdg sox
     - sudo pip install musicbrainzngs pycdio
 
     # Testing dependencies

README.md

@@ -75,10 +75,7 @@ REQUIREMENTS
   - Required for drive offset and caching behavior to be stored in the config file
 - libsndfile, for reading wav files
 - flac, for reading flac files
-
-Additionally, if you're building from a git checkout:
-- autoconf
-- automake
+- sox, for track peak detection
 
 GETTING WHIPPER
 ----------------

morituri/program/sox.py

@@ -1,16 +1,24 @@
-import os
 import logging
+import os
 from subprocess import Popen, PIPE
 
 SOX = 'sox'
 
 def peak_level(track_path):
-	if not os.path.exists(track_path):
-		logging.warning("SoX peak detection failed: file not found")
-		return None
-	sox = Popen([SOX, track_path, "-n", "stat"], stderr=PIPE)
-	out, err = sox.communicate()
-	if sox.returncode:
-		logging.warning("SoX peak detection failed: " + s.returncode)
-		return None
-	return float(err.split('\n')[3].split()[2])	# Maximum amplitude: 0.123456
+    """
+    Accepts a path to a sox-decodable audio file.
+
+    Returns track peak level from sox ('maximum amplitude') as a float.
+    Returns None on error.
+    """
+    if not os.path.exists(track_path):
+        logging.warning("SoX peak detection failed: file not found")
+        return None
+    sox = Popen([SOX, track_path, "-n", "stat"], stderr=PIPE)
+    out, err = sox.communicate()
+    if sox.returncode:
+        logging.warning("SoX peak detection failed: " + str(sox.returncode))
+        return None
+    # relevant captured line looks like:
+    # Maximum amplitude: 0.123456
+    return float(err.splitlines()[3].split()[2])

morituri/test/test_program_sox.py

@@ -0,0 +1,13 @@
+# -*- Mode: Python; test-case-name: morituri.test.test_program_sox -*-
+
+import os
+
+from morituri.program import sox
+from morituri.test import common
+
+class PeakLevelTestCase(common.TestCase):
+    def setUp(self):
+        self.path = os.path.join(os.path.dirname(__file__), 'track.flac')
+
+    def testParse(self):
+        self.assertEquals(0.800018, sox.peak_level(self.path))