Googletest export

Add a matcher `testing::ReturnRoundRobin` which, on each call, returns the next element in the sequence, restarting at the beginning once it has reached the end.

PiperOrigin-RevId: 276312136

googlemock/include/gmock/gmock-actions.h

@@ -716,6 +716,36 @@ class ReturnRefOfCopyAction {
   GTEST_DISALLOW_ASSIGN_(ReturnRefOfCopyAction);
 };
 
+// Implements the polymorphic ReturnRoundRobin(v) action, which can be
+// used in any function that returns the element_type of v.
+template <typename T>
+class ReturnRoundRobinAction {
+ public:
+  explicit ReturnRoundRobinAction(std::vector<T> values) {
+    GTEST_CHECK_(!values.empty())
+        << "ReturnRoundRobin requires at least one element.";
+    state_->values = std::move(values);
+  }
+
+  template <typename... Args>
+  T operator()(Args&&...) const {
+     return state_->Next();
+  }
+
+ private:
+  struct State {
+    T Next() {
+      T ret_val = values[i++];
+      if (i == values.size()) i = 0;
+      return ret_val;
+    }
+
+    std::vector<T> values;
+    size_t i = 0;
+  };
+  std::shared_ptr<State> state_ = std::make_shared<State>();
+};
+
 // Implements the polymorphic DoDefault() action.
 class DoDefaultAction {
  public:
@@ -1039,6 +1069,23 @@ internal::ByMoveWrapper<R> ByMove(R x) {
   return internal::ByMoveWrapper<R>(std::move(x));
 }
 
+// Creates an action that returns an element of `vals`. Calling this action will
+// repeatedly return the next value from `vals` until it reaches the end and
+// will restart from the beginning.
+template <typename T>
+internal::ReturnRoundRobinAction<T> ReturnRoundRobin(std::vector<T> vals) {
+  return internal::ReturnRoundRobinAction<T>(std::move(vals));
+}
+
+// Creates an action that returns an element of `vals`. Calling this action will
+// repeatedly return the next value from `vals` until it reaches the end and
+// will restart from the beginning.
+template <typename T>
+internal::ReturnRoundRobinAction<T> ReturnRoundRobin(
+    std::initializer_list<T> vals) {
+  return internal::ReturnRoundRobinAction<T>(std::vector<T>(vals));
+}
+
 // Creates an action that does the default action for the give mock function.
 inline internal::DoDefaultAction DoDefault() {
   return internal::DoDefaultAction();