update following feedback

python/cudf/cudf/_lib/json.pyx

@@ -227,13 +227,10 @@ cdef data_type _get_cudf_data_type_from_dtype(object dtype) except *:
 
 
 def _dtype_to_names_list(col):
-    cdef list child_names = []
     if isinstance(col.dtype, cudf.StructDtype):
-        for child_col, name in zip(col.children, list(col.dtype.fields)):
-            child_names.append((name, _dtype_to_names_list(child_col)))
+        return [(name, _dtype_to_names_list(child))
+                for name, child in zip(col.dtype.fields, col.children)]
     elif isinstance(col.dtype, cudf.ListDtype):
-        for child_col in col.children:
-            list_child_names = _dtype_to_names_list(child_col)
-            child_names.append(("", list_child_names))
-
-    return child_names
+        return [("", _dtype_to_names_list(child))
+                for child in col.children]
+    return []

python/cudf/cudf/_lib/pylibcudf/io/types.pyx

@@ -29,9 +29,9 @@ cdef class TableWithMetadata:
 
     Parameters
     ----------
-    tbl: Table
+    tbl : Table
         The input table.
-    column_names: list
+    column_names : list
         A list of tuples each containing the name of each column
         and the names of its child columns (in the same format).
         e.g.
@@ -193,6 +193,10 @@ cdef class SinkInfo:
         cdef unique_ptr[data_sink] sink
 
         cdef vector[string] paths
+
+        if not sinks:
+            raise ValueError("Need to pass at least one sink")
+
         if isinstance(sinks[0], io.StringIO):
             data_sinks.reserve(len(sinks))
             for s in sinks:

python/cudf/cudf/_lib/pylibcudf/libcudf/io/types.pxd

@@ -75,6 +75,7 @@ cdef extern from "cudf/io/types.hpp" \
         vector[column_name_info] children
 
     cdef cppclass table_metadata:
+        table_metadata() except +
 
         vector[string] column_names
         map[string, string] user_data

python/cudf/cudf/pylibcudf_tests/common/utils.py

@@ -133,12 +133,32 @@ def is_string(plc_dtype: plc.DataType):
 def is_fixed_width(plc_dtype: plc.DataType):
     return (
         is_integer(plc_dtype)
+        or is_unsigned_integer(plc_dtype)
         or is_floating(plc_dtype)
         or is_boolean(plc_dtype)
     )
 
 
+def is_nested_struct(pa_type: pa.DataType):
+    if isinstance(pa_type, pa.StructType):
+        for i in range(pa_type.num_fields):
+            if isinstance(pa_type[i].type, pa.StructType):
+                return True
+    return False
+
+
+def is_nested_list(pa_type: pa.DataType):
+    if isinstance(pa_type, pa.ListType):
+        return isinstance(pa_type.value_type, pa.ListType)
+    return False
+
+
 def sink_to_str(sink):
+    """
+    Takes a sink (e.g. StringIO/BytesIO, filepath, etc.)
+    and reads in the contents into a string (str not bytes)
+    for comparison
+    """
     if isinstance(sink, (str, os.PathLike)):
         with open(sink, "r") as f:
             str_result = f.read()
@@ -151,8 +171,7 @@ def sink_to_str(sink):
     return str_result
 
 
-# TODO: enable uint64, some failing tests
-NUMERIC_PA_TYPES = [pa.int64(), pa.float64()]  # pa.uint64()]
+NUMERIC_PA_TYPES = [pa.int64(), pa.float64(), pa.uint64()]
 STRING_PA_TYPES = [pa.string()]
 BOOL_PA_TYPES = [pa.bool_()]
 LIST_PA_TYPES = [
@@ -187,10 +206,8 @@ def sink_to_str(sink):
     + BOOL_PA_TYPES
     # exclude nested list/struct cases
     # since not all tests work with them yet
-    + LIST_PA_TYPES[:1]
-    + DEFAULT_PA_STRUCT_TESTING_TYPES[:1]
+    + LIST_PA_TYPES  # [:1]
+    + DEFAULT_PA_STRUCT_TESTING_TYPES  # [:1]
 )
 
-ALL_PA_TYPES = (
-    DEFAULT_PA_TYPES + LIST_PA_TYPES[1:] + DEFAULT_PA_STRUCT_TESTING_TYPES[1:]
-)
+ALL_PA_TYPES = DEFAULT_PA_TYPES  # + LIST_PA_TYPES[1:] + DEFAULT_PA_STRUCT_TESTING_TYPES[1:]

python/cudf/cudf/pylibcudf_tests/conftest.py

@@ -57,6 +57,8 @@ def table_data(request):
     # plc.io.TableWithMetadata
     colnames = []
 
+    np.random.seed(42)
+
     for typ in ALL_PA_TYPES:
         rand_vals = np.random.randint(0, nrows, nrows)
         child_colnames = []