test: fix failed testcase

Author: shuoweil

bigframes/display/html.py

@@ -183,13 +183,17 @@ def _explode_array_columns(
     """Explode array columns into new rows."""
     exploded_rows = []
     array_row_groups: dict[str, list[int]] = {}
-    for orig_idx, row in dataframe.iterrows():
+    non_array_columns = dataframe.columns.drop(array_columns).tolist()
+    non_array_df = dataframe[non_array_columns]
+
+    for orig_idx in dataframe.index:
+        non_array_data = non_array_df.loc[orig_idx].to_dict()
         array_values = {}
         max_len_in_row = 0
         non_na_array_found = False
 
         for col_name in array_columns:
-            val = row[col_name]
+            val = dataframe.loc[orig_idx, col_name]
             if val is not None and not (
                 isinstance(val, list) and len(val) == 1 and pd.isna(val[0])
             ):
@@ -200,7 +204,7 @@ def _explode_array_columns(
                 array_values[col_name] = []
 
         if not non_na_array_found:
-            new_row = row.copy()
+            new_row = non_array_data.copy()
             for col_name in array_columns:
                 new_row[f"{col_name}"] = pd.NA
             exploded_rows.append(new_row)
@@ -212,11 +216,7 @@ def _explode_array_columns(
 
         # Create one row per array element, up to max_len_in_row
         for array_idx in range(max_len_in_row):
-            new_row = row.copy()
-
-            # Remove array columns from the row copy
-            for col_name in array_columns:
-                new_row = new_row.drop(col_name)
+            new_row = non_array_data.copy()
 
             # Add the specific array element for this index
             for col_name in array_columns:
@@ -234,7 +234,8 @@ def _explode_array_columns(
             array_row_groups[orig_key].append(len(exploded_rows) - 1)
 
     if exploded_rows:
-        exploded_df = pd.DataFrame(exploded_rows)
+        # Reconstruct the DataFrame to maintain original column order
+        exploded_df = pd.DataFrame(exploded_rows)[dataframe.columns]
         for col in exploded_df.columns:
             # After explosion, object columns that are all-numeric (except for NAs)
             # should be converted to a numeric dtype for proper alignment.