robin-sparkless 0.11.4

PySpark-like DataFrame API in Rust on Polars; no JVM.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52

"""
Tests for issue #245: Column.desc_nulls_last() and nulls ordering methods not found.

With robin-sparkless 0.7.0, col("value").desc_nulls_last() and similar methods
(desc_nulls_first, asc_nulls_last, asc_nulls_first) were not available.
PySpark supports these for controlling null placement in orderBy.
"""

from __future__ import annotations

import robin_sparkless as rs


def test_column_has_desc_nulls_last() -> None:
    """Column has desc_nulls_last method (PySpark parity)."""
    c = rs.col("value")
    assert hasattr(c, "desc_nulls_last")
    assert hasattr(c, "desc_nulls_first")
    assert hasattr(c, "asc_nulls_last")
    assert hasattr(c, "asc_nulls_first")


def test_order_by_desc_nulls_last() -> None:
    """order_by_exprs with col().desc_nulls_last() puts nulls last."""
    spark = rs.SparkSession.builder().app_name("nulls_order").get_or_create()
    data = [{"value": "A"}, {"value": "B"}, {"value": None}, {"value": "C"}]
    schema = [("value", "string")]
    df = spark.createDataFrame(data, schema)
    out = df.order_by_exprs([rs.col("value").desc_nulls_last()]).collect()
    assert len(out) == 4
    # Desc with nulls last: C, B, A, null
    values = [r["value"] for r in out]
    assert values[0] == "C"
    assert values[1] == "B"
    assert values[2] == "A"
    assert values[3] is None


def test_order_by_asc_nulls_first() -> None:
    """order_by_exprs with col().asc_nulls_first() puts nulls first."""
    spark = rs.SparkSession.builder().app_name("nulls_order").get_or_create()
    data = [{"value": "A"}, {"value": "B"}, {"value": None}, {"value": "C"}]
    schema = [("value", "string")]
    df = spark.createDataFrame(data, schema)
    out = df.order_by_exprs([rs.col("value").asc_nulls_first()]).collect()
    assert len(out) == 4
    # Asc with nulls first: null, A, B, C
    values = [r["value"] for r in out]
    assert values[0] is None
    assert values[1] == "A"
    assert values[2] == "B"
    assert values[3] == "C"