Disallow creating invalid int_ts entirely

tests/test_types_basic.py

@@ -46,6 +46,14 @@ def test_int_too_short():
         t.uint16_t.deserialize(b"\x00")
 
 
+def test_int_out_of_bounds():
+    with pytest.raises(ValueError):
+        t.uint8_t(-1)
+
+    with pytest.raises(ValueError):
+        t.uint8_t(0xFF + 1)
+
+
 def test_bytes():
     data = b"abcde\x00\xff"
 
@@ -95,7 +103,7 @@ class TestList(t.LVList, item_type=t.uint8_t, length_type=t.uint8_t):
 
     assert isinstance(d, TestList)
 
-    with pytest.raises(OverflowError):
+    with pytest.raises(ValueError):
         TestList([1, 2, 0xFFFF, 4]).serialize()
 
 

zigpy_znp/types/basic.py

@@ -28,8 +28,21 @@ class int_t(int):
     _signed = True
     _size = None
 
+    def __new__(cls, value):
+        instance = int.__new__(cls, value)
+
+        if instance._signed is not None and instance._size is not None:
+            # It's a concrete int_t type, check to make sure it's valid
+            instance.serialize()
+
+        return instance
+
     def serialize(self) -> bytes:
-        return self.to_bytes(self._size, "little", signed=self._signed)
+        try:
+            return self.to_bytes(self._size, "little", signed=self._signed)
+        except OverflowError as e:
+            # OverflowError is not a subclass of ValueError, making it annoying to catch
+            raise ValueError(str(e)) from e
 
     @classmethod
     def deserialize(cls, data: bytes) -> typing.Tuple["int_t", bytes]: