feat: Support df.info() with null index

Author: TrevorBergeron

bigframes/core/blocks.py

@@ -252,6 +252,10 @@ def from_local(
                 pass
         return block
 
+    @property
+    def has_index(self) -> bool:
+        return len(self._index_columns) > 0
+
     @property
     def index(self) -> BlockIndexProperties:
         """Row identities for values in the Block."""

bigframes/dataframe.py

@@ -489,7 +489,6 @@ def memory_usage(self, index: bool = True):
             column_sizes = pandas.concat([index_size, column_sizes])
         return column_sizes
 
-    @validations.requires_index
     def info(
         self,
         verbose: Optional[bool] = None,
@@ -512,12 +511,17 @@ def info(
 
         obuf.write(f"{type(self)}\n")
 
-        index_type = "MultiIndex" if self.index.nlevels > 1 else "Index"
+        if self._block.has_index:
+            index_type = "MultiIndex" if self.index.nlevels > 1 else "Index"
 
-        # These accessses are kind of expensive, maybe should try to skip?
-        first_indice = self.index[0]
-        last_indice = self.index[-1]
-        obuf.write(f"{index_type}: {n_rows} entries, {first_indice} to {last_indice}\n")
+            # These accessses are kind of expensive, maybe should try to skip?
+            first_indice = self.index[0]
+            last_indice = self.index[-1]
+            obuf.write(
+                f"{index_type}: {n_rows} entries, {first_indice} to {last_indice}\n"
+            )
+        else:
+            obuf.write("NullIndex\n")
 
         dtype_strings = self.dtypes.astype("string")
         if show_all_columns:

tests/system/small/test_null_index.py

@@ -13,6 +13,8 @@
 # limitations under the License.
 
 
+import io
+
 import pandas as pd
 import pytest
 
@@ -44,6 +46,38 @@ def test_null_index_materialize(scalars_df_null_index, scalars_pandas_df_default
     )
 
 
+def test_null_index_info(scalars_df_null_index):
+    expected = (
+        "<class 'bigframes.dataframe.DataFrame'>\n"
+        "NullIndex\n"
+        "Data columns (total 14 columns):\n"
+        "  #  Column         Non-Null Count    Dtype\n"
+        "---  -------------  ----------------  ------------------------------\n"
+        "  0  bool_col       8 non-null        boolean\n"
+        "  1  bytes_col      6 non-null        binary[pyarrow]\n"
+        "  2  date_col       7 non-null        date32[day][pyarrow]\n"
+        "  3  datetime_col   6 non-null        timestamp[us][pyarrow]\n"
+        "  4  geography_col  4 non-null        geometry\n"
+        "  5  int64_col      8 non-null        Int64\n"
+        "  6  int64_too      9 non-null        Int64\n"
+        "  7  numeric_col    6 non-null        decimal128(38, 9)[pyarrow]\n"
+        "  8  float64_col    7 non-null        Float64\n"
+        "  9  rowindex_2     9 non-null        Int64\n"
+        " 10  string_col     8 non-null        string\n"
+        " 11  time_col       6 non-null        time64[us][pyarrow]\n"
+        " 12  timestamp_col  6 non-null        timestamp[us, tz=UTC][pyarrow]\n"
+        " 13  duration_col   7 non-null        duration[us][pyarrow]\n"
+        "dtypes: Float64(1), Int64(3), binary[pyarrow](1), boolean(1), date32[day][pyarrow](1), decimal128(38, 9)[pyarrow](1), duration[us][pyarrow](1), geometry(1), string(1), time64[us][pyarrow](1), timestamp[us, tz=UTC][pyarrow](1), timestamp[us][pyarrow](1)\n"
+        "memory usage: 1269 bytes\n"
+    )
+
+    bf_result = io.StringIO()
+
+    scalars_df_null_index.drop(columns="rowindex").info(buf=bf_result)
+
+    assert expected == bf_result.getvalue()
+
+
 def test_null_index_series_repr(scalars_df_null_index, scalars_pandas_df_default_index):
     bf_result = scalars_df_null_index["int64_too"].head(5).__repr__()
     pd_result = (