Implement Queue.__hash__.

Refs: #50

src/lib.rs

@@ -1,3 +1,4 @@
+use std::collections::hash_map::DefaultHasher;
 use std::hash::{Hash, Hasher};
 
 use pyo3::exceptions::PyIndexError;
@@ -1129,6 +1130,16 @@ impl QueuePy {
                 .all(|r| r.unwrap_or(false))
     }
 
+    fn __hash__(&self, py: Python<'_>) -> PyResult<u64> {
+        let hash = PyModule::import(py, "builtins")?.getattr("hash")?;
+        let mut hasher = DefaultHasher::new();
+        for each in &self.inner {
+            let n: i64 = hash.call1((each.into_py(py),))?.extract()?;
+            hasher.write_i64(n);
+        }
+        Ok(hasher.finish())
+    }
+
     fn __ne__(&self, other: &Self, py: Python<'_>) -> bool {
         (self.inner.len() != other.inner.len())
             || self

tests/test_queue.py

@@ -89,12 +89,6 @@ def test_repr():
     assert str(Queue([1, 2, 3])) in "Queue([1, 2, 3])"
 
 
-@pytest.mark.xfail(reason=HASH_MSG)
-def test_hashing():
-    assert hash(Queue([1, 2])) == hash(Queue([1, 2]))
-    assert hash(Queue([1, 2])) != hash(Queue([2, 1]))
-
-
 def test_sequence():
     m = Queue("asdf")
     assert m == Queue(["a", "s", "d", "f"])
@@ -131,3 +125,15 @@ def test_more_eq():
     assert not (Queue([o, o]) != Queue([o, o]))
     assert not (Queue([o]) != Queue([o]))
     assert not (Queue() != Queue([]))
+
+
+def test_hashing():
+    assert hash(Queue([1, 2])) == hash(Queue([1, 2]))
+    assert hash(Queue([1, 2])) != hash(Queue([2, 1]))
+    assert len({Queue([1, 2]), Queue([1, 2])}) == 1
+
+
+def test_unhashable_contents():
+    q = Queue([1, {1}])
+    with pytest.raises(TypeError):
+        hash(q)