def test_concat_str() -> None:
df = pl.DataFrame({"a": ["a", "b", "c"], "b": [1, 2, 3]})
out = df[[pl.concat_str(["a", "b"], sep="-")]]
assert out["a"] == ["a-1", "a-2", "a-3"]
out = df.select([pl.format("foo_{}_bar_{}", pl.col("a"), "b").alias("fmt")])
assert out["fmt"].to_list() == ["foo_a_bar_1", "foo_b_bar_2", "foo_c_bar_3"]
def test_wildcard_expansion() -> None:
# one function requires wildcard expansion the other need
# this tests the nested behavior
# see: #2867
df = pl.DataFrame({"a": ["x", "Y", "z"], "b": ["S", "o", "S"]})
assert df.select(
pl.concat_str(pl.all()).str.to_lowercase()
).to_series().to_list() == ["xs", "yo", "zs"]
def test_concat_str():
df = pl.DataFrame({"a": ["a", "b", "c"], "b": [1, 2, 3]})
out = df[[pl.concat_str(["a", "b"], delimiter="-")]]
assert out["a"] == ["a-1", "a-2", "a-3"]
import polars as pl
df = pl.DataFrame({"a": ["a", "b", "c"], "b": [1, 2, 3]})
out = df[[pl.concat_str(["a", "b"])]]