SERVER-35686 Add move assignment to promise.

Since `Promise` now can only be correctly created using
`makePromiseFuture`, we can now make `Promise` move assignable.

1 files changed, 14 insertions, 0 deletions

diff --git a/src/mongo/util/future_test_promise_int.cpp b/src/mongo/util/future_test_promise_int.cpp
index 144fae7ed5f..1145bb59e49 100644
--- a/src/mongo/util/future_test_promise_int.cpp
+++ b/src/mongo/util/future_test_promise_int.cpp
@@ -100,5 +100,19 @@ TEST(Promise, Fail_setWith_Future) {
     });
 }
 
+TEST(Promise, MoveAssignBreaksPromise) {
+    auto pf = makePromiseFuture<int>();
+    pf.promise = Promise<int>();  // This should break the promise.
+    ASSERT_THROWS_CODE(std::move(pf.future).get(), DBException, ErrorCodes::BrokenPromise);
+}
+
+TEST(Promise, MoveAssignedPromiseIsTheSameAsTheOldOne) {
+    const int kResult = 11;
+    auto pf = makePromiseFuture<int>();
+    auto promise = std::move(pf.promise);
+    promise.emplaceValue(kResult);
+    ASSERT_EQ(std::move(pf.future).get(), kResult);
+}
+
 }  // namespace
 }  // namespace mongo