Support doc link for the sklearn module. (#10287)

tests/python/test_basic.py

@@ -9,6 +9,7 @@ import pytest
 
 import xgboost as xgb
 from xgboost import testing as tm
+from xgboost.core import _parse_version
 
 dpath = "demo/data/"
 rng = np.random.RandomState(1994)
@@ -315,3 +316,14 @@ class TestBasicPathLike:
         """An invalid model_file path should raise XGBoostError."""
         with pytest.raises(xgb.core.XGBoostError):
             xgb.Booster(model_file=Path("invalidpath"))
+
+
+def test_parse_ver() -> None:
+    (major, minor, patch), post = _parse_version("2.1.0")
+    assert post == ""
+    (major, minor, patch), post = _parse_version("2.1.0-dev")
+    assert post == "dev"
+    (major, minor, patch), post = _parse_version("2.1.0rc1")
+    assert post == "rc1"
+    (major, minor, patch), post = _parse_version("2.1.0.post1")
+    assert post == "post1"

tests/python/test_with_sklearn.py

@@ -1484,3 +1484,16 @@ def test_tags() -> None:
 
     tags = xgb.XGBRanker()._more_tags()
     assert "multioutput" not in tags
+
+
+def test_doc_link() -> None:
+    for est in [
+        xgb.XGBRegressor(),
+        xgb.XGBClassifier(),
+        xgb.XGBRanker(),
+        xgb.XGBRFRegressor(),
+        xgb.XGBRFClassifier(),
+    ]:
+        name = est.__class__.__name__
+        link = est._get_doc_link()
+        assert f"xgboost.{name}" in link