From a96a508d906c5c31de06573583ec8c5fd7a2de9b Mon Sep 17 00:00:00 2001
From: Derek Jones <dtj1s@uw.edu>
Date: Tue, 15 Oct 2024 10:06:30 -0700
Subject: [PATCH] Make helper classes private, address code coverage issues.

Some of the dict-like overloads were an overachievement.
---
 src/nested_pandas/nestedframe/core.py             | 15 ++++-----------
 .../nested_pandas/nestedframe/test_nestedframe.py |  4 ++++
 2 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/src/nested_pandas/nestedframe/core.py b/src/nested_pandas/nestedframe/core.py
index d772b1c..bf2ea6f 100644
--- a/src/nested_pandas/nestedframe/core.py
+++ b/src/nested_pandas/nestedframe/core.py
@@ -69,7 +69,7 @@ def _constructor_expanddim(self) -> Self:  # type: ignore[name-defined] # noqa:
     __pandas_priority__ = 3500
 
 
-class NestResolver(dict):
+class _NestResolver(dict):
     """
     Used by NestedFrame.eval to resolve the names of nests at the top level.
     While the resolver is normally a dictionary, with values that are fixed
@@ -83,22 +83,15 @@ def __init__(self, outer: NestedFrame):
         super().__init__()
 
     def __contains__(self, item):
-        if not isinstance(item, str):
-            return False
         top_nest = item if "." not in item else item.split(".")[0].strip()
         return top_nest in self._outer.nested_columns
 
-    def __len__(self):
-        return len(self._outer.nested_columns)
-
     def __getitem__(self, item):
-        if not isinstance(item, str):
-            raise KeyError(f"Unknown nest {item}")
         top_nest = item if "." not in item else item.split(".")[0].strip()
         if not super().__contains__(top_nest):
             if top_nest not in self._outer.nested_columns:
                 raise KeyError(f"Unknown nest {top_nest}")
-            super().__setitem__(top_nest, NestedFieldResolver(top_nest, self._outer))
+            super().__setitem__(top_nest, _NestedFieldResolver(top_nest, self._outer))
         return super().__getitem__(top_nest)
 
     def __setitem__(self, key, value):
@@ -110,7 +103,7 @@ def __setitem__(self, key, value):
         pass
 
 
-class NestedFieldResolver:
+class _NestedFieldResolver:
     """
     Used by NestedFrame.eval to resolve the names of fields in nested columns when
     encountered in expressions, interpreting __getattr__ in terms of a
@@ -448,7 +441,7 @@ def eval(self, expr: str, *, inplace: bool = False, **kwargs) -> Any | None:
         --------
         https://pandas.pydata.org/docs/reference/api/pandas.eval.html
         """
-        kwargs["resolvers"] = tuple(kwargs.get("resolvers", ())) + (NestResolver(self),)
+        kwargs["resolvers"] = tuple(kwargs.get("resolvers", ())) + (_NestResolver(self),)
         kwargs["inplace"] = inplace
         kwargs["parser"] = "nested-pandas"
         return super().eval(expr, **kwargs)
diff --git a/tests/nested_pandas/nestedframe/test_nestedframe.py b/tests/nested_pandas/nestedframe/test_nestedframe.py
index 1590529..eb7c3f3 100644
--- a/tests/nested_pandas/nestedframe/test_nestedframe.py
+++ b/tests/nested_pandas/nestedframe/test_nestedframe.py
@@ -860,6 +860,10 @@ def test_eval_assignment():
     assert (nf_nx["packed.f"] == nf["a"] + nf["packed.c"]).all()
     assert (nf_nx["packed.f"] == pd.Series([1, 3, 5, 12, 6, 5, 4, 7, 4], index=to_pack.index)).all()
 
+    # Only supporting one level of nesting at present.
+    with pytest.raises(ValueError):
+        nf.eval("packed.c.inner = packed.c * 2 + packed.d")
+
     # Assigning to new base columns from nested columns.  This can't be done because
     # it would attempt to create base column values that were "between indexes", or as
     # Pandas puts, duplicate index labels.