a real system for mocking IO for UI functions

test/_common.py

@@ -1,5 +1,6 @@
 """Some common functionality for beets' test cases."""
 import time
+import sys
 
 class Timecop(object):
     """Mocks the timing system (namely time() and sleep()) for testing.
@@ -25,3 +26,48 @@ class Timecop(object):
     def restore(self):
         time.time = self.orig['time']
         time.sleep = self.orig['sleep']
+
+class DummyOut(object):
+    encoding = 'utf8'
+    def __init__(self):
+        self.buf = []
+    def write(self, s):
+        self.buf.append(s)
+    def get(self):
+        return ''.join(self.buf)
+    def clear(self):
+        self.buf = []
+class DummyIn(object):
+    encoding = 'utf8'
+    def __init__(self):
+        self.buf = []
+        self.reads = 0
+    def add(self, s):
+        self.buf.append(s + '\n')
+    def readline(self):
+        self.reads += 1
+        return self.buf.pop(0)
+class DummyIO(object):
+    """Mocks input and output streams for testing UI code."""
+    def __init__(self):
+        self.stdin = DummyIn()
+        self.stdout = DummyOut()
+
+    def addinput(self, s):
+        self.stdin.add(s)
+
+    def getoutput(self):
+        res = self.stdout.get()
+        self.stdout.clear()
+        return res
+    
+    def readcount(self):
+        return self.stdin.reads
+
+    def install(self):
+        sys.stdin = self.stdin
+        sys.stdout = self.stdout
+
+    def restore(self):
+        sys.stdin = sys.__stdin__
+        sys.stdout = sys.__stdout__

test/test_albumify.py

@@ -19,16 +19,16 @@ import sys
 
 sys.path.append('..')
 from beets import library
-from beets import ui
 from beetsplug.albumify import albumify
+import _common
 
 from test_db import item
 
-# Silence UI output.
-ui.print_ = lambda s: None
-
 class AlbumifyTest(unittest.TestCase):
     def setUp(self):
+        self.io = _common.DummyIO()
+        self.io.install()
+
         self.lib = library.Library(':memory:')
         i1, i2, i3 = item(), item(), item()
         i1.album = 'album1'
@@ -38,6 +38,9 @@ class AlbumifyTest(unittest.TestCase):
         self.lib.add(i2)
         self.lib.add(i3)
 
+    def tearDown(self):
+        self.io.restore()
+
     def test_albumify_creates_albums(self):
         albumify(self.lib)
         albums = [a.album for a in self.lib.albums()]

test/test_ui.py

@@ -18,56 +18,41 @@
 import unittest
 import sys
 import os
+import _common
 sys.path.append('..')
 from beets import library
 from beets import ui
 from beets.ui import commands
 import test_db
 
-# Dummy printing so we can get the commands' output.
-outbuffer = []
-def buffer_append(*txt):
-    outbuffer.extend(txt)
-def get_output():
-    return u' '.join(outbuffer)
-def clear_buffer():
-    outbuffer[:]
-
 class ListTest(unittest.TestCase):
     def setUp(self):
-        self.old_print = ui.print_
-        ui.print_ = buffer_append
-        commands.print_ = buffer_append
+        self.io = _common.DummyIO()
+        self.io.install()
 
-        clear_buffer()
         self.lib = library.Library(':memory:')
         i = test_db.item()
         self.lib.add(i)
 
     def tearDown(self):
-        ui.print_ = self.old_print
-        commands.print_ = self.old_print
+        self.io.restore()
         
     def test_list_outputs_item(self):
         commands.list_items(self.lib, '', False)
-        out = get_output()
+        out = self.io.getoutput()
         self.assertTrue(u'the title' in out)
     
     def test_list_album_omits_title(self):
         commands.list_items(self.lib, '', True)
-        out = get_output()
+        out = self.io.getoutput()
         self.assertTrue(u'the title' not in out)
     
 class PrintTest(unittest.TestCase):
     def setUp(self):
-        class Devnull(object):
-            def write(self, d):
-                pass
-        self.stdout = sys.stdout
-        sys.stdout = Devnull()
-
+        self.io = _common.DummyIO()
+        self.io.install()
     def tearDown(self):
-        sys.stdout = self.stdout
+        self.io.restore()
     
     def test_print_without_locale(self):
         lang = os.environ.get('LANG')
@@ -104,13 +89,14 @@ class PrintTest(unittest.TestCase):
 
 class InputTest(unittest.TestCase):
     def setUp(self):
-        def my_input(prompt=None):
-            return '\xc3\x82me'
-        commands.raw_input = my_input
+        self.io = _common.DummyIO()
+        self.io.install()
     def tearDown(self):
-        commands.raw_input = raw_input
+        self.io.restore()
 
     def test_manual_search_gets_unicode(self):
+        self.io.addinput('\xc3\x82me')
+        self.io.addinput('\xc3\x82me')
         artist, album = commands.manual_search()
         self.assertEqual(artist, u'\xc2me')
         self.assertEqual(album, u'\xc2me')