add tests

py-polars/tests/unit/namespaces/test_string.py

@@ -537,6 +537,39 @@ def test_extract_all_many() -> None:
     assert df["foo"].str.extract_all(df["re"]).to_list() == [["a"], ["bc"], ["abc"]]
 
 
+def test_extract_groups() -> None:
+    def _named_groups_builder(pattern: str, groups: dict[str, str]) -> str:
+        return pattern.format(
+            **{name: f"(?<{name}>{value})" for name, value in groups.items()}
+        )
+
+    expected = {
+        "authority": ["ISO", "ISO/IEC/IEEE"],
+        "spec_num": ["80000", "29148"],
+        "part_num": ["1", None],
+        "revision_year": ["2009", "2018"],
+    }
+
+    pattern = _named_groups_builder(
+        r"{authority}\s{spec_num}(?:-{part_num})?(?::{revision_year})",
+        {
+            "authority": r"^ISO(?:/[A-Z]+)*",
+            "spec_num": r"\d+",
+            "part_num": r"\d+",
+            "revision_year": r"\d{4}",
+        },
+    )
+
+    df = pl.DataFrame({"iso_code": ["ISO 80000-1:2009", "ISO/IEC/IEEE 29148:2018"]})
+
+    assert (
+        df.select(pl.col("iso_code").str.extract_groups(pattern))
+        .unnest("iso_code")
+        .to_dict(False)
+        == expected
+    )
+
+
 def test_zfill() -> None:
     df = pl.DataFrame(
         {