add lint rule, PR title should include reference while hotfix (#26)

src/pr_lint/linter.py

@@ -1,7 +1,7 @@
 from github.Label import Label
 from github.PullRequest import PullRequest
 
-from .utils import get_owner
+from .utils import extract_reference_number, get_owner
 
 
 def lint(pr: PullRequest) -> None:
@@ -37,3 +37,10 @@ def lint(pr: PullRequest) -> None:
     assert len(impact_labels) == 1, "There should be exactly one Impact label"
 
     # TODO: check if the PR title is in the correct format (e.g. commitlint convention)
+
+    # Check the PR fit the hotfix format
+    # get the base branch name of the PR
+    base_branch = pr.base.ref
+    if base_branch.startswith("stable/"):
+        # it is a hotfix
+        assert extract_reference_number(pr.title), "Hotfix PR should have a reference number"

src/pr_lint/tests/test_utils.py

@@ -1,4 +1,4 @@
-from ..utils import collect_emojis_from_labels, extract_owner_from_title, extract_pure_title
+from ..utils import collect_emojis_from_labels, extract_owner_from_title, extract_pure_title, extract_reference_number
 
 
 def test_extract_owner_from_title() -> None:
@@ -9,6 +9,14 @@ def test_extract_owner_from_title() -> None:
     assert extract_owner_from_title(title) is None
 
 
+def test_extract_reference_number() -> None:
+    title = "This is a PR title (#123)"
+    assert extract_reference_number(title) == "123"
+
+    title = "This is a PR title #123"
+    assert extract_reference_number(title) is None
+
+
 def test_extract_pure_title() -> None:
     title = "🚀 This is a PR title @owner"
     assert extract_pure_title(title) == "This is a PR title"

src/pr_lint/utils.py

@@ -34,6 +34,23 @@ def extract_owner_from_title(title: str) -> str | None:
     return None
 
 
+def extract_reference_number(title: str) -> str | None:
+    """
+    Extract the reference number from the title.
+
+    Args:
+        title: The title of the pull request
+
+    Returns:
+        The reference number of the pull request
+    """
+    pr_number = re.findall(r"\(#(\d+)\)", title.strip())
+    if pr_number:
+        return pr_number[0]
+
+    return None
+
+
 def get_owner(pr: PullRequest) -> str | None:
     """
     Get the owner of a pull request.