Improve test coverage

nilmdb/utils/diskusage.py

@@ -11,10 +11,9 @@ def human_size(num):
         unit, num_decimals = unit_list[exponent]
         format_string = '{:.%sf} {}' % (num_decimals)
         return format_string.format(quotient, unit)
-    if num == 0: # pragma: no cover
-        return '0 bytes'
-    if num == 1: # pragma: no cover
+    elif num == 1:
         return '1 byte'
+    return '0 bytes'
 
 def du(path):
     """Like du -sb, returns total size of path in bytes.  Ignore
@@ -28,7 +27,7 @@ def du(path):
                 filepath = os.path.join(path, thisfile)
                 size += du(filepath)
         return size
-    except OSError as e: # pragma: no cover
-        if e.errno != errno.ENOENT:
+    except OSError as e:
+        if e.errno != errno.ENOENT: # pragma: no cover
             raise
         return 0

tests/test_misc.py

@@ -70,3 +70,26 @@ class TestMisc(object):
             nilmdb.utils.fallocate.punch_hole("/", 1, 1, False)
         # no exception because we ignore errors by default
         nilmdb.utils.fallocate.punch_hole(fn, 1, -1)
+
+    def test_diskusage(self):
+        hs = nilmdb.utils.diskusage.human_size
+        eq_(hs(0), "0 bytes")
+        eq_(hs(1), "1 byte")
+        eq_(hs(1023), "1023 bytes")
+
+        eq_(hs(1024), "1 kiB")
+
+        eq_(hs(1048575), "1024 kiB")
+        eq_(hs(1048576), "1.0 MiB")
+
+        eq_(hs(1073741823), "1024.0 MiB")
+        eq_(hs(1073741824), "1.00 GiB")
+
+        eq_(hs(1099511627775), "1024.00 GiB")
+        eq_(hs(1099511627776), "1.00 TiB")
+
+        eq_(hs(1099511627776 * 5000.1234), "5000.12 TiB")
+
+        nilmdb.utils.diskusage.du("/dev")
+        with assert_raises(OSError):
+            nilmdb.utils.diskusage.du("/dev/null/bogus")