Ensure audb.Repository is hashable (#491)

* Ensure audb.Repository is hashable

* Update tests/test_repository.py

Co-authored-by: sourcery-ai[bot] <58596630+sourcery-ai[bot]@users.noreply.github.com>

* Add missing return type

* Extend test docstring

---------

Co-authored-by: sourcery-ai[bot] <58596630+sourcery-ai[bot]@users.noreply.github.com>

audb/core/repository.py

@@ -71,6 +71,15 @@ def __eq__(self, other) -> bool:
         """
         return str(self) == str(other)
 
+    def __hash__(self) -> int:
+        """Hash of repository.
+
+        Returns:
+            hash of repository
+
+        """
+        return hash(str(self))
+
     def __repr__(self):  # noqa: D105
         return (
             f"Repository("

tests/test_repository.py

@@ -43,6 +43,67 @@ def test_repository_eq(repository1, repository2, expected):
     assert (repository1 == repository2) == expected
 
 
+@pytest.mark.parametrize(
+    "repo1, repo2, should_have_same_hash",
+    [
+        # Same repositories should have same hash
+        (
+            audb.Repository("repo", "host", "file-system"),
+            audb.Repository("repo", "host", "file-system"),
+            True,
+        ),
+        # Different attributes should have different hashes
+        (
+            audb.Repository("repo1", "host", "file-system"),
+            audb.Repository("repo2", "host", "file-system"),
+            False,
+        ),
+        (
+            audb.Repository("repo", "host1", "file-system"),
+            audb.Repository("repo", "host2", "file-system"),
+            False,
+        ),
+        (
+            audb.Repository("repo", "host", "file-system"),
+            audb.Repository("repo", "host", "s3"),
+            False,
+        ),
+    ],
+)
+def test_repository_hash(repo1, repo2, should_have_same_hash):
+    """Test Repository object hash behavior.
+
+    Tests that:
+    - Repository objects are hashable
+    - Equal repositories have same hash
+    - Different repositories have different hashes
+
+    Args:
+        repo1: repository object
+        repo2: repository object
+        should_have_same_hash: if ``True``,
+            expects ``repo1`` and ``repo2``
+            to be the same object
+
+    """
+    # Verify objects are hashable
+    assert isinstance(hash(repo1), int)
+    assert isinstance(hash(repo2), int)
+
+    # Test hash equality matches object equality
+    if should_have_same_hash:
+        assert hash(repo1) == hash(repo2)
+        assert repo1 == repo2
+    else:
+        assert hash(repo1) != hash(repo2)
+        assert repo1 != repo2
+
+    # Verify can be used in sets
+    test_set = {repo1, repo2}
+    expected_len = 1 if should_have_same_hash else 2
+    assert len(test_set) == expected_len
+
+
 @pytest.mark.parametrize(
     "backend, host, repo, expected",
     [