Allow integers in conversion to float array messages (RobotWebTools#777)

Fixes RobotWebTools#764 by using `ndarray`/`array` assignment operations that accept ints as well as floats, rather than directly assigning the incoming list value, which failed at the msg/idl generated python code's validation step.

rosbridge_library/src/rosbridge_library/internal/message_conversion.py

@@ -358,8 +358,13 @@ def _to_list_inst(msg, rostype, roottype, inst, stack):
         return []
 
     # Special mappings for numeric types https://design.ros2.org/articles/idl_interface_definition.html
-    if isinstance(inst, array.array) or isinstance(inst, np.ndarray):
-        return msg
+    if isinstance(inst, array.array):
+        del inst[:]
+        inst.extend(msg)  # accepts both ints and floats which may come from json
+        return inst
+    if isinstance(inst, np.ndarray):
+        inst[:] = msg  # accepts both ints and floats which may come from json
+        return inst
 
     # Remove the list indicators from the rostype
     try:

rosbridge_library/test/internal/test_message_conversion.py

@@ -299,10 +299,20 @@ def test_float32_msg(rostype, data):
             ret = test_float32_msg(rostype, floats)
             np.testing.assert_array_equal(ret, np.array(floats))
 
+            # From List[int]
+            ints = list(map(int, range(0, 256)))
+            ret = test_float32_msg(rostype, ints)
+            np.testing.assert_array_equal(ret, np.array(ints))
+
         for msgtype in ["TestFloat32BoundedArray"]:
             rostype = "rosbridge_test_msgs/" + msgtype
 
             # From List[float]
             floats = list(map(float, range(0, 16)))
             ret = test_float32_msg(rostype, floats)
             np.testing.assert_array_equal(ret, np.array(floats))
+
+            # From List[int]
+            ints = list(map(int, range(0, 16)))
+            ret = test_float32_msg(rostype, ints)
+            np.testing.assert_array_equal(ret, np.array(ints))