diff --git a/tests/unit/test_repo_prs_helpers.py b/tests/unit/test_repo_prs_helpers.py
new file mode 100644
index 0000000..7dfa096
--- /dev/null
+++ b/tests/unit/test_repo_prs_helpers.py
@@ -0,0 +1,276 @@
+from __future__ import annotations
+
+import unittest
+
+from contribarena.tools.repo_prs import (
+    _assignees,
+    _from_gh,
+    _from_rest,
+    _labels,
+    _linked_issues,
+    _optional_str,
+)
+
+
+class LabelsTest(unittest.TestCase):
+    def test_empty_list(self) -> None:
+        self.assertEqual([], _labels([]))
+
+    def test_none_input(self) -> None:
+        self.assertEqual([], _labels(None))
+
+    def test_non_list_input(self) -> None:
+        self.assertEqual([], _labels("not a list"))
+        self.assertEqual([], _labels({}))
+        self.assertEqual([], _labels(123))
+
+    def test_dict_items_with_name(self) -> None:
+        raw = [{"name": "bug"}, {"name": "enhancement"}]
+        self.assertEqual(["bug", "enhancement"], _labels(raw))
+
+    def test_string_items(self) -> None:
+        raw = ["bug", "enhancement"]
+        self.assertEqual(["bug", "enhancement"], _labels(raw))
+
+    def test_mixed_dict_and_string(self) -> None:
+        raw = [{"name": "bug"}, "feature", {"name": "docs"}]
+        self.assertEqual(["bug", "feature", "docs"], _labels(raw))
+
+    def test_empty_name_filtered(self) -> None:
+        raw = [{"name": ""}, {"name": "bug"}]
+        self.assertEqual(["bug"], _labels(raw))
+
+    def test_none_name_filtered(self) -> None:
+        raw = [{"name": None}, {"name": "bug"}]
+        self.assertEqual(["bug"], _labels(raw))
+
+    def test_empty_string_filtered(self) -> None:
+        raw = ["", "bug"]
+        self.assertEqual(["bug"], _labels(raw))
+
+    def test_dict_without_name_key(self) -> None:
+        raw = [{"label": "bug"}, {"name": "feature"}]
+        self.assertEqual(["feature"], _labels(raw))
+
+
+class LinkedIssuesTest(unittest.TestCase):
+    def test_empty_list(self) -> None:
+        self.assertEqual([], _linked_issues([]))
+
+    def test_none_input(self) -> None:
+        self.assertEqual([], _linked_issues(None))
+
+    def test_non_list_input(self) -> None:
+        self.assertEqual([], _linked_issues("not a list"))
+        self.assertEqual([], _linked_issues({}))
+
+    def test_dict_items_with_number(self) -> None:
+        raw = [{"number": 42}, {"number": 123}]
+        self.assertEqual([42, 123], _linked_issues(raw))
+
+    def test_string_number_converted(self) -> None:
+        raw = [{"number": "42"}, {"number": "123"}]
+        self.assertEqual([42, 123], _linked_issues(raw))
+
+    def test_missing_number_filtered(self) -> None:
+        raw = [{}, {"number": 42}]
+        self.assertEqual([42], _linked_issues(raw))
+
+    def test_zero_number_filtered(self) -> None:
+        raw = [{"number": 0}, {"number": 42}]
+        self.assertEqual([42], _linked_issues(raw))
+
+    def test_none_number_filtered(self) -> None:
+        raw = [{"number": None}, {"number": 42}]
+        self.assertEqual([42], _linked_issues(raw))
+
+    def test_non_dict_item_skipped(self) -> None:
+        raw = ["not a dict", {"number": 42}]
+        self.assertEqual([42], _linked_issues(raw))
+
+
+class AssigneesTest(unittest.TestCase):
+    def test_empty_assignees(self) -> None:
+        self.assertEqual([], _assignees({}))
+
+    def test_no_assignees_key(self) -> None:
+        self.assertEqual([], _assignees({"title": "issue"}))
+
+    def test_assignees_not_list(self) -> None:
+        self.assertEqual([], _assignees({"assignees": "not a list"}))
+        self.assertEqual([], _assignees({"assignees": None}))
+
+    def test_single_assignee(self) -> None:
+        item = {"assignees": [{"login": "alice"}]}
+        self.assertEqual(["alice"], _assignees(item))
+
+    def test_multiple_assignees(self) -> None:
+        item = {"assignees": [{"login": "alice"}, {"login": "bob"}]}
+        self.assertEqual(["alice", "bob"], _assignees(item))
+
+    def test_empty_login_returns_empty_string(self) -> None:
+        item = {"assignees": [{"login": ""}, {"login": "alice"}]}
+        self.assertEqual(["", "alice"], _assignees(item))
+
+    def test_none_login_returns_empty_string(self) -> None:
+        item = {"assignees": [{"login": None}, {"login": "alice"}]}
+        self.assertEqual(["", "alice"], _assignees(item))
+
+    def test_non_dict_item_skipped(self) -> None:
+        item = {"assignees": ["not a dict", {"login": "alice"}]}
+        self.assertEqual(["alice"], _assignees(item))
+
+
+class OptionalStrTest(unittest.TestCase):
+    def test_none_returns_none(self) -> None:
+        self.assertIsNone(_optional_str(None))
+
+    def test_empty_string_returns_none(self) -> None:
+        self.assertIsNone(_optional_str(""))
+
+    def test_string_value(self) -> None:
+        self.assertEqual("2026-05-31T00:00:00Z", _optional_str("2026-05-31T00:00:00Z"))
+
+    def test_non_string_converted(self) -> None:
+        self.assertEqual("42", _optional_str(42))
+        self.assertEqual("True", _optional_str(True))
+
+    def test_zero_returns_none(self) -> None:
+        self.assertIsNone(_optional_str(0))
+
+    def test_false_returns_none(self) -> None:
+        self.assertIsNone(_optional_str(False))
+
+
+class FromGhTest(unittest.TestCase):
+    def test_minimal_item(self) -> None:
+        item = {"number": 1}
+        pr = _from_gh(item)
+        self.assertEqual(1, pr.number)
+        self.assertEqual("", pr.title)
+        self.assertEqual("", pr.url)
+        self.assertEqual("", pr.state)
+        self.assertEqual("", pr.author)
+        self.assertEqual("", pr.body)
+        self.assertEqual([], pr.labels)
+        self.assertIsNone(pr.created_at)
+        self.assertIsNone(pr.updated_at)
+        self.assertIsNone(pr.merged_at)
+        self.assertFalse(pr.draft)
+        self.assertEqual([], pr.linked_issues)
+
+    def test_full_item(self) -> None:
+        item = {
+            "number": 42,
+            "title": "Add feature",
+            "url": "https://github.com/owner/repo/pull/42",
+            "state": "OPEN",
+            "author": {"login": "alice"},
+            "body": "Description",
+            "labels": [{"name": "enhancement"}],
+            "createdAt": "2026-05-31T00:00:00Z",
+            "updatedAt": "2026-05-31T01:00:00Z",
+            "mergedAt": "2026-05-31T02:00:00Z",
+            "isDraft": False,
+            "closingIssuesReferences": [{"number": 123}],
+        }
+        pr = _from_gh(item)
+        self.assertEqual(42, pr.number)
+        self.assertEqual("Add feature", pr.title)
+        self.assertEqual("https://github.com/owner/repo/pull/42", pr.url)
+        self.assertEqual("OPEN", pr.state)
+        self.assertEqual("alice", pr.author)
+        self.assertEqual("Description", pr.body)
+        self.assertEqual(["enhancement"], pr.labels)
+        self.assertEqual("2026-05-31T00:00:00Z", pr.created_at)
+        self.assertEqual("2026-05-31T01:00:00Z", pr.updated_at)
+        self.assertEqual("2026-05-31T02:00:00Z", pr.merged_at)
+        self.assertFalse(pr.draft)
+        self.assertEqual([123], pr.linked_issues)
+
+    def test_author_not_dict(self) -> None:
+        item = {"number": 1, "author": "alice"}
+        pr = _from_gh(item)
+        self.assertEqual("alice", pr.author)
+
+    def test_author_none(self) -> None:
+        item = {"number": 1, "author": None}
+        pr = _from_gh(item)
+        self.assertEqual("", pr.author)
+
+    def test_draft_true(self) -> None:
+        item = {"number": 1, "isDraft": True}
+        pr = _from_gh(item)
+        self.assertTrue(pr.draft)
+
+    def test_number_as_string(self) -> None:
+        item = {"number": "42"}
+        pr = _from_gh(item)
+        self.assertEqual(42, pr.number)
+
+
+class FromRestTest(unittest.TestCase):
+    def test_minimal_item(self) -> None:
+        item = {"number": 1}
+        pr = _from_rest(item)
+        self.assertEqual(1, pr.number)
+        self.assertEqual("", pr.title)
+        self.assertEqual("", pr.url)
+        self.assertEqual("", pr.state)
+        self.assertEqual("", pr.author)
+        self.assertEqual("", pr.body)
+        self.assertEqual([], pr.labels)
+        self.assertIsNone(pr.created_at)
+        self.assertIsNone(pr.updated_at)
+        self.assertIsNone(pr.merged_at)
+        self.assertFalse(pr.draft)
+
+    def test_full_item(self) -> None:
+        item = {
+            "number": 42,
+            "title": "Add feature",
+            "html_url": "https://github.com/owner/repo/pull/42",
+            "state": "open",
+            "user": {"login": "alice"},
+            "body": "Description",
+            "created_at": "2026-05-31T00:00:00Z",
+            "updated_at": "2026-05-31T01:00:00Z",
+            "merged_at": "2026-05-31T02:00:00Z",
+            "draft": False,
+        }
+        pr = _from_rest(item)
+        self.assertEqual(42, pr.number)
+        self.assertEqual("Add feature", pr.title)
+        self.assertEqual("https://github.com/owner/repo/pull/42", pr.url)
+        self.assertEqual("open", pr.state)
+        self.assertEqual("alice", pr.author)
+        self.assertEqual("Description", pr.body)
+        self.assertEqual([], pr.labels)  # REST does not include labels
+        self.assertEqual("2026-05-31T00:00:00Z", pr.created_at)
+        self.assertEqual("2026-05-31T01:00:00Z", pr.updated_at)
+        self.assertEqual("2026-05-31T02:00:00Z", pr.merged_at)
+        self.assertFalse(pr.draft)
+
+    def test_user_not_dict(self) -> None:
+        item = {"number": 1, "user": "alice"}
+        pr = _from_rest(item)
+        self.assertEqual("", pr.author)
+
+    def test_user_none(self) -> None:
+        item = {"number": 1, "user": None}
+        pr = _from_rest(item)
+        self.assertEqual("", pr.author)
+
+    def test_draft_true(self) -> None:
+        item = {"number": 1, "draft": True}
+        pr = _from_rest(item)
+        self.assertTrue(pr.draft)
+
+    def test_labels_always_empty(self) -> None:
+        item = {"number": 1, "labels": [{"name": "bug"}]}
+        pr = _from_rest(item)
+        self.assertEqual([], pr.labels)
+
+
+if __name__ == "__main__":
+    unittest.main()