Add tests for pickling and exception wrapping

Also raise `NotImplementedError` when `DiceBaseException` wrap is used
incorrectly.

dice/exceptions.py

@@ -8,7 +8,9 @@ def from_other(cls, other):
             return DiceException(*other.args)
         elif isinstance(other, ParseFatalException):
             return DiceFatalException(*other.args)
-        return cls(*other.args)
+        raise NotImplementedError(
+            'DiceBaseException can only wrap ParseException or ParseFatalException'
+        )
 
     def pretty_print(self):
         string, location, description = self.args

dice/tests/test_elements.py

@@ -1,7 +1,8 @@
 from __future__ import absolute_import
 
 from dice.constants import DiceExtreme
-from dice.exceptions import DiceFatalException
+from dice.exceptions import DiceException, DiceFatalException
+import pickle
 from pytest import raises
 import random
 
@@ -135,6 +136,13 @@ def test_roll_error(self):
             rolled = roll("6d6")
             rolled.do_roll_single(4, 3)
 
+    def test_invalid_wrap(self):
+        with raises(NotImplementedError):
+            try:
+                raise RuntimeError('blah')
+            except Exception as e:
+                raise DiceException.from_other(e)
+
 
 class TestEvaluate(object):
     def test_cache(self):
@@ -191,3 +199,18 @@ def test_sysrandom_op(self):
 
     def test_sysrandom_roll(self):
         roll("6d6", random=self.sysrandom)
+
+
+class TestPickle(object):
+    for expr in [
+        '-d20',
+        '4d6t',
+        '+-(1,2,3)',
+        '2d20h',
+        '4d6h3s',
+        '4dF - 2',
+        '4*d%'
+    ]:
+        value = roll(expr, raw=True, single=False)
+        pickled = pickle.dumps(value)
+        clone = pickle.loads(pickled)