Added additional test

py/server/tests/test_parquet.py

@@ -391,6 +391,32 @@ def test_dates_and_time(self):
         self.assert_table_equals(dh_table.select(["someDateColumn", "someTimeColumn"]),
                                  from_disk_pandas.select(["someDateColumn", "someTimeColumn"]))
 
+    def test_time_with_different_units(self):
+        """ Test that we can write and read time columns with different units """
+        dh_table = empty_table(20000).update(formulas=[
+            "someTimeColumn = i % 10 == 0 ? null : java.time.LocalTime.of(i%24, i%60, (i+10)%60)"
+        ])
+        write(dh_table, "data_from_dh.parquet")
+        table = pyarrow.parquet.read_table('data_from_dh.parquet')
+
+        def time_test_helper(pa_table, new_schema, dest):
+            # Write the provided pyarrow table type-casted to the new schema
+            pyarrow.parquet.write_table(pa_table.cast(new_schema), dest)
+            from_disk = read(dest)
+            df_from_disk = to_pandas(from_disk)
+            original_df = pa_table.to_pandas()
+            # Compare the dataframes as strings
+            print((df_from_disk.astype(str) == original_df.astype(str)).all().values.all())
+
+        # Test for nanoseconds, microseconds, and milliseconds
+        schema_nsec = table.schema.set(0, pyarrow.field('someTimeColumn', pyarrow.time64('ns')))
+        time_test_helper(table, schema_nsec, "data_from_pq_nsec.parquet")
+
+        schema_usec = table.schema.set(0, pyarrow.field('someTimeColumn', pyarrow.time64('us')))
+        time_test_helper(table, schema_usec, "data_from_pq_usec.parquet")
+
+        schema_msec = table.schema.set(0, pyarrow.field('someTimeColumn', pyarrow.time32('ms')))
+        time_test_helper(table, schema_msec, "data_from_pq_msec.parquet")
 
 if __name__ == '__main__':
     unittest.main()