1# Actions Reference 2 3[**Actions**](../gmock_for_dummies.md#actions-what-should-it-do) specify what a 4mock function should do when invoked. This page lists the built-in actions 5provided by GoogleTest. All actions are defined in the `::testing` namespace. 6 7## Returning a Value 8 9| Action | Description | 10| :-------------------------------- | :-------------------------------------------- | 11| `Return()` | Return from a `void` mock function. | 12| `Return(value)` | Return `value`. If the type of `value` is different to the mock function's return type, `value` is converted to the latter type <i>at the time the expectation is set</i>, not when the action is executed. | 13| `ReturnArg<N>()` | Return the `N`-th (0-based) argument. | 14| `ReturnNew<T>(a1, ..., ak)` | Return `new T(a1, ..., ak)`; a different object is created each time. | 15| `ReturnNull()` | Return a null pointer. | 16| `ReturnPointee(ptr)` | Return the value pointed to by `ptr`. | 17| `ReturnRef(variable)` | Return a reference to `variable`. | 18| `ReturnRefOfCopy(value)` | Return a reference to a copy of `value`; the copy lives as long as the action. | 19| `ReturnRoundRobin({a1, ..., ak})` | Each call will return the next `ai` in the list, starting at the beginning when the end of the list is reached. | 20 21## Side Effects 22 23| Action | Description | 24| :--------------------------------- | :-------------------------------------- | 25| `Assign(&variable, value)` | Assign `value` to variable. | 26| `DeleteArg<N>()` | Delete the `N`-th (0-based) argument, which must be a pointer. | 27| `SaveArg<N>(pointer)` | Save the `N`-th (0-based) argument to `*pointer`. | 28| `SaveArgPointee<N>(pointer)` | Save the value pointed to by the `N`-th (0-based) argument to `*pointer`. | 29| `SetArgReferee<N>(value)` | Assign `value` to the variable referenced by the `N`-th (0-based) argument. | 30| `SetArgPointee<N>(value)` | Assign `value` to the variable pointed by the `N`-th (0-based) argument. | 31| `SetArgumentPointee<N>(value)` | Same as `SetArgPointee<N>(value)`. Deprecated. Will be removed in v1.7.0. | 32| `SetArrayArgument<N>(first, last)` | Copies the elements in source range [`first`, `last`) to the array pointed to by the `N`-th (0-based) argument, which can be either a pointer or an iterator. The action does not take ownership of the elements in the source range. | 33| `SetErrnoAndReturn(error, value)` | Set `errno` to `error` and return `value`. | 34| `Throw(exception)` | Throws the given exception, which can be any copyable value. Available since v1.1.0. | 35 36## Using a Function, Functor, or Lambda as an Action 37 38In the following, by "callable" we mean a free function, `std::function`, 39functor, or lambda. 40 41| Action | Description | 42| :---------------------------------- | :------------------------------------- | 43| `f` | Invoke `f` with the arguments passed to the mock function, where `f` is a callable. | 44| `Invoke(f)` | Invoke `f` with the arguments passed to the mock function, where `f` can be a global/static function or a functor. | 45| `Invoke(object_pointer, &class::method)` | Invoke the method on the object with the arguments passed to the mock function. | 46| `InvokeWithoutArgs(f)` | Invoke `f`, which can be a global/static function or a functor. `f` must take no arguments. | 47| `InvokeWithoutArgs(object_pointer, &class::method)` | Invoke the method on the object, which takes no arguments. | 48| `InvokeArgument<N>(arg1, arg2, ..., argk)` | Invoke the mock function's `N`-th (0-based) argument, which must be a function or a functor, with the `k` arguments. | 49 50The return value of the invoked function is used as the return value of the 51action. 52 53When defining a callable to be used with `Invoke*()`, you can declare any unused 54parameters as `Unused`: 55 56```cpp 57using ::testing::Invoke; 58double Distance(Unused, double x, double y) { return sqrt(x*x + y*y); } 59... 60EXPECT_CALL(mock, Foo("Hi", _, _)).WillOnce(Invoke(Distance)); 61``` 62 63`Invoke(callback)` and `InvokeWithoutArgs(callback)` take ownership of 64`callback`, which must be permanent. The type of `callback` must be a base 65callback type instead of a derived one, e.g. 66 67```cpp 68 BlockingClosure* done = new BlockingClosure; 69 ... Invoke(done) ...; // This won't compile! 70 71 Closure* done2 = new BlockingClosure; 72 ... Invoke(done2) ...; // This works. 73``` 74 75In `InvokeArgument<N>(...)`, if an argument needs to be passed by reference, 76wrap it inside `std::ref()`. For example, 77 78```cpp 79using ::testing::InvokeArgument; 80... 81InvokeArgument<2>(5, string("Hi"), std::ref(foo)) 82``` 83 84calls the mock function's #2 argument, passing to it `5` and `string("Hi")` by 85value, and `foo` by reference. 86 87## Default Action 88 89| Action | Description | 90| :------------ | :----------------------------------------------------- | 91| `DoDefault()` | Do the default action (specified by `ON_CALL()` or the built-in one). | 92 93{: .callout .note} 94**Note:** due to technical reasons, `DoDefault()` cannot be used inside a 95composite action - trying to do so will result in a run-time error. 96 97## Composite Actions 98 99| Action | Description | 100| :----------------------------- | :------------------------------------------ | 101| `DoAll(a1, a2, ..., an)` | Do all actions `a1` to `an` and return the result of `an` in each invocation. The first `n - 1` sub-actions must return void and will receive a readonly view of the arguments. | 102| `IgnoreResult(a)` | Perform action `a` and ignore its result. `a` must not return void. | 103| `WithArg<N>(a)` | Pass the `N`-th (0-based) argument of the mock function to action `a` and perform it. | 104| `WithArgs<N1, N2, ..., Nk>(a)` | Pass the selected (0-based) arguments of the mock function to action `a` and perform it. | 105| `WithoutArgs(a)` | Perform action `a` without any arguments. | 106 107## Defining Actions 108 109| Macro | Description | 110| :--------------------------------- | :-------------------------------------- | 111| `ACTION(Sum) { return arg0 + arg1; }` | Defines an action `Sum()` to return the sum of the mock function's argument #0 and #1. | 112| `ACTION_P(Plus, n) { return arg0 + n; }` | Defines an action `Plus(n)` to return the sum of the mock function's argument #0 and `n`. | 113| `ACTION_Pk(Foo, p1, ..., pk) { statements; }` | Defines a parameterized action `Foo(p1, ..., pk)` to execute the given `statements`. | 114 115The `ACTION*` macros cannot be used inside a function or class. 116