Fix byte{s,array}.join

tests/snippets/bytearray.py

@@ -271,6 +271,9 @@ assert bytearray(b"").join(
 ) == bytearray(b"jiljlkmoomkaaaa")
 with assert_raises(TypeError):
     bytearray(b"").join((b"km", "kl"))
+assert bytearray(b"abc").join((
+    bytearray(b"123"), bytearray(b"xyz")
+)) == bytearray(b"123abcxyz")
 
 
 # endswith startswith

tests/snippets/bytes.py

@@ -270,6 +270,8 @@ assert (
 with assert_raises(TypeError):
     b"".join((b"km", "kl"))
 
+assert b"abc".join((b"123", b"xyz")) == b"123abcxyz"
+
 
 # endswith startswith
 assert b"abcde".endswith(b"de")

vm/src/obj/objbytearray.rs

@@ -290,7 +290,7 @@ impl PyByteArrayRef {
     }
 
     #[pymethod(name = "join")]
-    fn join(self, iter: PyIterable, vm: &VirtualMachine) -> PyResult {
+    fn join(self, iter: PyIterable<PyByteInner>, vm: &VirtualMachine) -> PyResult {
         self.inner.borrow().join(iter, vm)
     }
 

vm/src/obj/objbyteinner.rs

@@ -826,11 +826,14 @@ impl PyByteInner {
         Ok(total)
     }
 
-    pub fn join(&self, iter: PyIterable, vm: &VirtualMachine) -> PyResult {
+    pub fn join(&self, iter: PyIterable<PyByteInner>, vm: &VirtualMachine) -> PyResult {
         let mut refs = vec![];
         for v in iter.iter(vm)? {
             let v = v?;
-            refs.extend(PyByteInner::try_from_object(vm, v)?.elements)
+            if !refs.is_empty() {
+                refs.extend(&self.elements);
+            }
+            refs.extend(v.elements);
         }
 
         Ok(vm.ctx.new_bytes(refs))

vm/src/obj/objbytes.rs

@@ -263,7 +263,7 @@ impl PyBytesRef {
     }
 
     #[pymethod(name = "join")]
-    fn join(self, iter: PyIterable, vm: &VirtualMachine) -> PyResult {
+    fn join(self, iter: PyIterable<PyByteInner>, vm: &VirtualMachine) -> PyResult {
         self.inner.join(iter, vm)
     }