Fix redundant and missed checks

Signed-off-by: Alexey Stepanov <penguinolog@gmail.com>

binfield/binfield.py

@@ -114,7 +114,6 @@ def _get_index(val):
         return slice(*val)
     if isinstance(val, dict):
         return slice(*val['_index_'])
-    raise TypeError('Unexpected index format: {!r}'.format(val))
 
 
 def _get_idx(val):
@@ -214,6 +213,10 @@ def __new__(mcs, name, bases, classdict):
                 raise TypeError(
                     'Pre-defined size has invalid type: {!r}'.format(size)
                 )
+
+            if size <= 0:
+                raise ValueError('Size must be positive value !')
+
             mask_from_size = (1 << size) - 1
 
         mask = classdict.get('_mask_', mask_from_size)
@@ -223,6 +226,9 @@ def __new__(mcs, name, bases, classdict):
                 raise TypeError(
                     'Pre-defined mask has invalid type: {!r}'.format(mask)
                 )
+            if mask < 0:
+                raise ValueError('BitMask is strictly positive!')
+
             if size is None:
                 size = mask.bit_length()
 

test/test_baseFunc.py

@@ -258,3 +258,40 @@ class NestedMappedBinField(BinField):
             '(0xC1) (0b11000001)>'
         )
         self.assertEqual(nbf[:], nbf)  # Full slice calls self-copy
+
+    def test_negative(self):
+        with self.assertRaises(TypeError):
+            class NewBinField(BinField):
+                pass
+
+            class NestedBitField(NewBinField):
+                pass
+
+        with self.assertRaises(ValueError):
+            class UnexpectedIndex(BinField):
+                _index_ = (0, 10)
+
+        with self.assertRaises(IndexError):
+            class IntersectIndexes(BinField):
+                first = (0, 2)
+                second = (1, 3)
+
+        with self.assertRaises(TypeError):
+            class IncorrectSizeType(BinField):
+                _size_ = 'Some size'
+
+        with self.assertRaises(ValueError):
+            class IncorrectSizeValue(BinField):
+                _size_ = -1
+
+        with self.assertRaises(TypeError):
+            class IncorrectMaskType(BinField):
+                _mask_ = 'Some mask'
+
+        with self.assertRaises(ValueError):
+            class IncorrectMaskValue(BinField):
+                _mask_ = -1
+
+        with self.assertRaises(TypeError):
+            class GarbageData(BinField):
+                value = 'Not recognized'