robin-sparkless 4.3.0

"""
Regression test for issue #1386: sql.show_databases parity.

PySpark scenario (from the issue):

    def scenario_sql_show_databases(session):
        return session.sql("SHOW DATABASES")

This test exercises the same scenario against sparkless, ensuring that:

- ``session.sql("SHOW DATABASES")`` does not raise.
- The resulting schema's ``simpleString()`` matches the current struct form.
- The data includes both ``default`` and ``global_temp`` databases.
- ``explain()`` returns a non-empty plan string (no blank UI).
"""

from sparkless.sql import SparkSession


def test_issue_1386_sql_show_databases_schema_data_and_explain() -> None:
    """sql.show_databases: schema, data, and explain behavior (issue #1386)."""
    spark = SparkSession.builder.appName("issue_1386").getOrCreate()
    try:
        df = spark.sql("SHOW DATABASES")

        # Schema simpleString should match the current struct representation.
        schema_str = df.schema.simpleString()
        assert schema_str == "struct<databaseName:string>"

        # Data should include both default and global_temp namespaces.
        rows = df.collect()
        names = [row["databaseName"] for row in rows]
        assert "default" in names
        assert "global_temp" in names

        # explain() should produce a non-empty plan string.
        plan = df.explain()
        assert isinstance(plan, str)
        assert plan.strip() != ""
    finally:
        spark.stop()