added test coverage for distutils.dep_util, and cleaned up the module

dep_util.py

@@ -9,29 +9,27 @@ __revision__ = "$Id$"
 import os
 from distutils.errors import DistutilsFileError
 
+def newer(source, target):
+    """Tells if the target is newer than the source.
 
-def newer (source, target):
-    """Return true if 'source' exists and is more recently modified than
-    'target', or if 'source' exists and 'target' doesn't.  Return false if
-    both exist and 'target' is the same age or younger than 'source'.
-    Raise DistutilsFileError if 'source' does not exist.
+    Return true if 'source' exists and is more recently modified than
+    'target', or if 'source' exists and 'target' doesn't.
+
+    Return false if both exist and 'target' is the same age or younger
+    than 'source'. Raise DistutilsFileError if 'source' does not exist.
+
+    Note that this test is not very accurate: files created in the same second
+    will have the same "age".
     """
     if not os.path.exists(source):
-        raise DistutilsFileError, ("file '%s' does not exist" %
-                                   os.path.abspath(source))
+        raise DistutilsFileError("file '%s' does not exist" %
+                                 os.path.abspath(source))
     if not os.path.exists(target):
-        return 1
-
-    from stat import ST_MTIME
-    mtime1 = os.stat(source)[ST_MTIME]
-    mtime2 = os.stat(target)[ST_MTIME]
-
-    return mtime1 > mtime2
-
-# newer ()
+        return True
 
+    return os.stat(source).st_mtime > os.stat(target).st_mtime
 
-def newer_pairwise (sources, targets):
+def newer_pairwise(sources, targets):
     """Walk two filename lists in parallel, testing if each source is newer
     than its corresponding target.  Return a pair of lists (sources,
     targets) where source is newer than target, according to the semantics
@@ -43,19 +41,18 @@ def newer_pairwise (sources, targets):
     # build a pair of lists (sources, targets) where  source is newer
     n_sources = []
     n_targets = []
-    for i in range(len(sources)):
-        if newer(sources[i], targets[i]):
-            n_sources.append(sources[i])
-            n_targets.append(targets[i])
+    for source, target in zip(sources, targets):
+        if newer(source, target):
+            n_sources.append(source)
+            n_targets.append(target)
 
-    return (n_sources, n_targets)
+    return n_sources, n_targets
 
-# newer_pairwise ()
-
-
-def newer_group (sources, target, missing='error'):
+def newer_group(sources, target, missing='error'):
     """Return true if 'target' is out-of-date with respect to any file
-    listed in 'sources'.  In other words, if 'target' exists and is newer
+    listed in 'sources'.
+
+    In other words, if 'target' exists and is newer
     than every file in 'sources', return false; otherwise return true.
     'missing' controls what we do when a source file is missing; the
     default ("error") is to blow up with an OSError from inside 'stat()';
@@ -68,14 +65,14 @@ def newer_group (sources, target, missing='error'):
     """
     # If the target doesn't even exist, then it's definitely out-of-date.
     if not os.path.exists(target):
-        return 1
+        return True
 
     # Otherwise we have to find out the hard way: if *any* source file
     # is more recent than 'target', then 'target' is out-of-date and
     # we can immediately return true.  If we fall through to the end
     # of the loop, then 'target' is up-to-date and we return false.
-    from stat import ST_MTIME
-    target_mtime = os.stat(target)[ST_MTIME]
+    target_mtime = os.stat(target).st_mtime
+
     for source in sources:
         if not os.path.exists(source):
             if missing == 'error':      # blow up when we stat() the file
@@ -83,12 +80,9 @@ def newer_group (sources, target, missing='error'):
             elif missing == 'ignore':   # missing source dropped from
                 continue                #  target's dependency list
             elif missing == 'newer':    # missing source means target is
-                return 1                #  out-of-date
+                return True             #  out-of-date
 
-        source_mtime = os.stat(source)[ST_MTIME]
-        if source_mtime > target_mtime:
-            return 1
-    else:
-        return 0
+        if os.stat(source).st_mtime > target_mtime:
+            return True
 
-# newer_group ()
+    return False

tests/test_dep_util.py

+"""Tests for distutils.dep_util."""
+import unittest
+import os
+import time
+
+from distutils.dep_util import newer, newer_pairwise, newer_group
+from distutils.errors import DistutilsFileError
+from distutils.tests import support
+
+# XXX needs to be tuned for the various platforms
+_ST_MIME_TIMER = 1
+
+class DepUtilTestCase(support.TempdirManager, unittest.TestCase):
+
+    def test_newer(self):
+        tmpdir = self.mkdtemp()
+        target = os.path.join(tmpdir, 'target')
+        source = os.path.join(tmpdir, 'source')
+
+        # Raise DistutilsFileError if 'source' does not exist.
+        self.assertRaises(DistutilsFileError, newer, target, source)
+
+        # Return true if 'source' exists and is more recently modified than
+        # 'target', or if 'source' exists and 'target' doesn't.
+        self.write_file(target)
+        self.assertTrue(newer(target, source))
+        self.write_file(source, 'xox')
+        time.sleep(_ST_MIME_TIMER)  # ensures ST_MTIME differs
+        self.write_file(target, 'xhx')
+        self.assertTrue(newer(target, source))
+
+        # Return false if both exist and 'target' is the same age or younger
+        # than 'source'.
+        self.write_file(source, 'xox'); self.write_file(target, 'xhx')
+        self.assertFalse(newer(target, source))
+        self.write_file(target, 'xox')
+        time.sleep(_ST_MIME_TIMER)
+        self.write_file(source, 'xhx')
+        self.assertFalse(newer(target, source))
+
+    def test_newer_pairwise(self):
+        tmpdir = self.mkdtemp()
+        sources = os.path.join(tmpdir, 'sources')
+        targets = os.path.join(tmpdir, 'targets')
+        os.mkdir(sources)
+        os.mkdir(targets)
+        one = os.path.join(sources, 'one')
+        two = os.path.join(sources, 'two')
+        three = os.path.join(targets, 'three')
+        four = os.path.join(targets, 'four')
+
+        self.write_file(one)
+        self.write_file(three)
+        self.write_file(four)
+        time.sleep(_ST_MIME_TIMER)
+        self.write_file(two)
+
+        self.assertEquals(newer_pairwise([one, two], [three, four]),
+                          ([two],[four]))
+
+    def test_newer_group(self):
+        tmpdir = self.mkdtemp()
+        sources = os.path.join(tmpdir, 'sources')
+        os.mkdir(sources)
+        one = os.path.join(sources, 'one')
+        two = os.path.join(sources, 'two')
+        three = os.path.join(sources, 'three')
+        target = os.path.join(tmpdir, 'target')
+
+        # return true if 'target' is out-of-date with respect to any file
+        # listed in 'sources'.
+        self.write_file(target)
+        time.sleep(_ST_MIME_TIMER)
+        self.write_file(one)
+        self.write_file(two)
+        self.write_file(three)
+        self.assertTrue(newer_group([one, two, three], target))
+
+        self.write_file(one)
+        self.write_file(three)
+        self.write_file(two)
+        time.sleep(0.1)
+        self.write_file(target)
+        self.assertFalse(newer_group([one, two, three], target))
+
+        # missing handling
+        os.remove(one)
+        self.assertRaises(OSError, newer_group, [one, two, three], target)
+
+        self.assertFalse(newer_group([one, two, three], target,
+                                     missing='ignore'))
+
+        self.assertTrue(newer_group([one, two, three], target,
+                                    missing='newer'))
+
+
+def test_suite():
+    return unittest.makeSuite(DepUtilTestCase)
+
+if __name__ == "__main__":
+    unittest.main(defaultTest="test_suite")