FIX-#4409: Fix eval_insert utility that doesn't actually check results of insert function

docs/release_notes/release_notes-0.15.0.rst

@@ -38,6 +38,7 @@ Key Features and Updates
   * FIX-#4422: get rid of case sensitivity for `warns_that_defaulting_to_pandas` (#4423)
   * TEST-#4426: Stop passing is_default kwarg to Modin and pandas (#4428)
   * FIX-#4439: Fix flake8 CI fail (#4440)
+  * FIX-#4409: Fix `eval_insert` utility that doesn't actually check results of `insert` function (#4410)
 * Documentation improvements
   * DOCS-#4296: Fix docs warnings (#4297)
   * DOCS-#4388: Turn off fail_on_warning option for docs build (#4389)

modin/pandas/dataframe.py

@@ -1161,7 +1161,11 @@ def insert(self, loc, column, value, allow_duplicates=False):  # noqa: PR01, D20
                 and not isinstance(value, (pandas.Series, Series))
                 and len(value) != len(self.index)
             ):
-                raise ValueError("Length of values does not match length of index")
+                raise ValueError(
+                    "Length of values ({}) does not match length of index ({})".format(
+                        len(value), len(self.index)
+                    )
+                )
             if not allow_duplicates and column in self.columns:
                 raise ValueError(f"cannot insert {column}, already exists")
             if not -len(self.columns) <= loc <= len(self.columns):

modin/pandas/test/dataframe/test_map_metadata.py

@@ -71,6 +71,7 @@ def eval_insert(modin_df, pandas_df, **kwargs):
         modin_df,
         pandas_df,
         operation=lambda df, **kwargs: df.insert(**kwargs),
+        __inplace__=True,
         **_kwargs,
     )
 
@@ -1049,7 +1050,6 @@ def comparator(df1, df2):
             loc=0,
             col=f"test_col{idx}",
             value=value,
-            __inplace__=True,
             comparator=lambda df1, df2: comparator(df1, df2),
         )