Merge pull request RustPython#3988 from jeffwang0516/starmap-reduce

Add `itertools.starmap.__reduce__`

Author: youknowone

Lib/test/test_itertools.py

@@ -1226,8 +1226,6 @@ def test_map(self):
             c = map(tupleize, 'abc', count())
             self.pickletest(proto, c)
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_starmap(self):
         self.assertEqual(list(starmap(operator.pow, zip(range(3), range(1,7)))),
                          [0**1, 1**2, 2**3])

vm/src/stdlib/itertools.rs

@@ -404,7 +404,15 @@ mod decl {
     }
 
     #[pyimpl(with(IterNext, Constructor), flags(BASETYPE))]
-    impl PyItertoolsStarmap {}
+    impl PyItertoolsStarmap {
+        #[pymethod(magic)]
+        fn reduce(zelf: PyRef<Self>) -> (PyTypeRef, (PyObjectRef, PyIter)) {
+            (
+                zelf.class().clone(),
+                (zelf.function.clone(), zelf.iterable.clone()),
+            )
+        }
+    }
     impl IterNextIterable for PyItertoolsStarmap {}
     impl IterNext for PyItertoolsStarmap {
         fn next(zelf: &Py<Self>, vm: &VirtualMachine) -> PyResult<PyIterReturn> {