Add dict.clear + test

src/runtime/dict.cpp

@@ -46,6 +46,12 @@ Box* dictRepr(BoxedDict* self) {
     return boxString(std::string(chars.begin(), chars.end()));
 }
 
+Box* dictClear(BoxedDict* self) {
+    RELEASE_ASSERT(self->cls == dict_cls, "");
+    self->d.clear();
+    return None;
+}
+
 Box* dictCopy(BoxedDict* self) {
     RELEASE_ASSERT(self->cls == dict_cls, "");
 
@@ -300,6 +306,7 @@ void setupDict() {
     dict_cls->giveAttr("__iter__",
                        new BoxedFunction(boxRTFunction((void*)dictIterKeys, typeFromClass(dict_iterator_cls), 1)));
 
+    dict_cls->giveAttr("clear", new BoxedFunction(boxRTFunction((void*)dictClear, NONE, 1)));
     dict_cls->giveAttr("copy", new BoxedFunction(boxRTFunction((void*)dictCopy, DICT, 1)));
 
     dict_cls->giveAttr("items", new BoxedFunction(boxRTFunction((void*)dictItems, LIST, 1)));

test/tests/dict.py

@@ -114,3 +114,14 @@ print d2, d
 d = {}
 print d.__init__((('a', 1), ('b', 2)), b=3)
 print sorted(d.items())
+
+# clear
+d = {1:2, 'a': 'b'}
+d.clear()
+
+print d
+
+d = {}
+d.clear()
+print d
+

test/tests/sys_modules_test.py

-# expected: fail
-# (del statement)
-
 # Not sure how important or necessary this behavior is, but
 # CPython's behavior around sys.modules seems to be that it saves
 # an internal reference to the object, so if you set sys.modules