chore(python): Remove trailing spaces in glimpse output (#6037)

py-polars/polars/internals/dataframe/frame.py

@@ -2589,7 +2589,7 @@ def glimpse(self: DF) -> str:
         ...         "f": [date(2020, 1, 1), date(2021, 1, 2), date(2022, 1, 1)],
         ...     }
         ... )
-        >>> df.glimpse()  # doctest: +IGNORE_RESULT
+        >>> print(df.glimpse())
         Rows: 3
         Columns: 6
         $ a <Float64> 1.0, 2.8, 3.0
@@ -2623,18 +2623,19 @@ def _parse_column(col_name: str) -> tuple[str, str, str]:
         # limit the amount of data printed such that total width is fixed
         max_col_values = 100 - max_col_name - max_col_dtype
 
+        output = StringIO()
         # print header
-        output = f"Rows: {self.height}\nColumns: {self.width}\n"
+        output.write(f"Rows: {self.height}\nColumns: {self.width}\n")
 
         # print individual columns: one row per column
         for col_name, dtype_str, val_str in data:
-            output += (
+            output.write(
                 f"$ {col_name:<{max_col_name}}"
                 f" {dtype_str:>{max_col_dtype}}"
-                f" {val_str:<{max_col_values}}\n"
+                f" {val_str:<{min(len(val_str), max_col_values)}}\n"
             )
 
-        return output
+        return output.getvalue()
 
     def describe(self: DF) -> DF:
         """

py-polars/tests/unit/test_df.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import sys
+import textwrap
 import typing
 from datetime import date, datetime, timedelta
 from decimal import Decimal
@@ -2497,19 +2498,19 @@ def test_glimpse() -> None:
     )
     result = df.glimpse()
 
-    # Strip trailing whitespace for the purposes of this test
-    result_lines = [line.strip() for line in result.strip().split("\n")]
-    expected_lines = [
-        "Rows: 3",
-        "Columns: 6",
-        "$ a <Float64> 1.0, 2.8, 3.0",
-        "$ b   <Int64> 4, 5, None",
-        "$ c <Boolean> True, False, True",
-        "$ d    <Utf8> None, b, c",
-        "$ e    <Utf8> usd, eur, None",
-        "$ f    <Date> 2020-01-01, 2021-01-02, 2022-01-01",
-    ]
-    assert result_lines == expected_lines
+    expected = textwrap.dedent(
+        """\
+        Rows: 3
+        Columns: 6
+        $ a <Float64> 1.0, 2.8, 3.0
+        $ b   <Int64> 4, 5, None
+        $ c <Boolean> True, False, True
+        $ d    <Utf8> None, b, c
+        $ e    <Utf8> usd, eur, None
+        $ f    <Date> 2020-01-01, 2021-01-02, 2022-01-01
+        """
+    )
+    assert result == expected
 
 
 def test_item() -> None: