Fix encoding of infinity (ultrajson#80).

Infinity was being encoded as 'Inf' which, whilst the JSON spec doesn't include
any non-finite floats, differs from the conventions in other JSON libraries,
JavaScript of using 'Infinity'. It also differs from what `ujson.loads()`
expects so that `ujson.loads(ujson.dumps(math.inf))` raises an exception.

Closes ultrajson#80.

python/objToJSON.c

@@ -887,7 +887,7 @@ PyObject* objToJSON(PyObject* self, PyObject *args, PyObject *kwargs)
 
   if (encoder.allowNan)
   {
-    csInf = "Inf";
+    csInf = "Infinity";
     csNan = "NaN";
   }
 

tests/test_ujson.py

@@ -842,8 +842,8 @@ def test_encode_no_assert(test_input):
         (1.0, "1.0"),
         (OrderedDict([(1, 1), (0, 0), (8, 8), (2, 2)]), '{"1":1,"0":0,"8":8,"2":2}'),
         ({"a": float("NaN")}, '{"a":NaN}'),
-        ({"a": float("inf")}, '{"a":Inf}'),
-        ({"a": -float("inf")}, '{"a":-Inf}'),
+        ({"a": float("inf")}, '{"a":Infinity}'),
+        ({"a": -float("inf")}, '{"a":-Infinity}'),
     ],
 )
 def test_encode(test_input, expected):