Actions Reference

Actions specify what a mock function should do when invoked. This page lists the built-in actions provided by GoogleTest. All actions are defined in the ::testing namespace.

Returning a Value

Action	Description
`Return()`	Return from a `void` mock function.
`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 at the time the expectation is set, not when the action is executed.
`ReturnArg<N>()`	Return the `N`-th (0-based) argument.
`ReturnNew<T>(a1, ..., ak)`	Return `new T(a1, ..., ak)`; a different object is created each time.
`ReturnNull()`	Return a null pointer.
`ReturnPointee(ptr)`	Return the value pointed to by `ptr`.
`ReturnRef(variable)`	Return a reference to `variable`.
`ReturnRefOfCopy(value)`	Return a reference to a copy of `value`; the copy lives as long as the action.
`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.

Side Effects

Action	Description
`Assign(&variable, value)`	Assign `value` to variable.
`DeleteArg<N>()`	Delete the `N`-th (0-based) argument, which must be a pointer.
`SaveArg<N>(pointer)`	Save the `N`-th (0-based) argument to `*pointer`.
`SaveArgPointee<N>(pointer)`	Save the value pointed to by the `N`-th (0-based) argument to `*pointer`.
`SetArgReferee<N>(value)`	Assign `value` to the variable referenced by the `N`-th (0-based) argument.
`SetArgPointee<N>(value)`	Assign `value` to the variable pointed by the `N`-th (0-based) argument.
`SetArgumentPointee<N>(value)`	Same as `SetArgPointee<N>(value)`. Deprecated. Will be removed in v1.7.0.
`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.
`SetErrnoAndReturn(error, value)`	Set `errno` to `error` and return `value`.
`Throw(exception)`	Throws the given exception, which can be any copyable value. Available since v1.1.0.

Using a Function, Functor, or Lambda as an Action

In the following, by “callable” we mean a free function, std::function, functor, or lambda.

Action	Description
`f`	Invoke `f` with the arguments passed to the mock function, where `f` is a callable.
`Invoke(f)`	Invoke `f` with the arguments passed to the mock function, where `f` can be a global/static function or a functor.
`Invoke(object_pointer, &class::method)`	Invoke the method on the object with the arguments passed to the mock function.
`InvokeWithoutArgs(f)`	Invoke `f`, which can be a global/static function or a functor. `f` must take no arguments.
`InvokeWithoutArgs(object_pointer, &class::method)`	Invoke the method on the object, which takes no arguments.
`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.

The return value of the invoked function is used as the return value of the action.

When defining a callable to be used with Invoke*(), you can declare any unused parameters as Unused:

using ::testing::Invoke;
double Distance(Unused, double x, double y) { return sqrt(x*x + y*y); }
...
EXPECT_CALL(mock, Foo("Hi", _, _)).WillOnce(Invoke(Distance));

Invoke(callback) and InvokeWithoutArgs(callback) take ownership of callback, which must be permanent. The type of callback must be a base callback type instead of a derived one, e.g.

  BlockingClosure* done = new BlockingClosure;
  ... Invoke(done) ...;  // This won't compile!

  Closure* done2 = new BlockingClosure;
  ... Invoke(done2) ...;  // This works.

In InvokeArgument<N>(...), if an argument needs to be passed by reference, wrap it inside std::ref(). For example,

using ::testing::InvokeArgument;
...
InvokeArgument<2>(5, string("Hi"), std::ref(foo))

calls the mock function’s #2 argument, passing to it 5 and string("Hi") by value, and foo by reference.

Default Action

Action	Description
`DoDefault()`	Do the default action (specified by `ON_CALL()` or the built-in one).

Note: due to technical reasons, DoDefault() cannot be used inside a composite action - trying to do so will result in a run-time error.

Composite Actions

Action	Description
`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.
`IgnoreResult(a)`	Perform action `a` and ignore its result. `a` must not return void.
`WithArg<N>(a)`	Pass the `N`-th (0-based) argument of the mock function to action `a` and perform it.
`WithArgs<N1, N2, ..., Nk>(a)`	Pass the selected (0-based) arguments of the mock function to action `a` and perform it.
`WithoutArgs(a)`	Perform action `a` without any arguments.

Defining Actions

Macro	Description
`ACTION(Sum) { return arg0 + arg1; }`	Defines an action `Sum()` to return the sum of the mock function’s argument #0 and #1.
`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`.
`ACTION_Pk(Foo, p1, ..., pk) { statements; }`	Defines a parameterized action `Foo(p1, ..., pk)` to execute the given `statements`.

The ACTION* macros cannot be used inside a function or class.