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diff --git a/googlemock/docs/cheat_sheet.md b/googlemock/docs/cheat_sheet.md new file mode 100644 index 0000000..239a4c6 --- /dev/null +++ b/googlemock/docs/cheat_sheet.md @@ -0,0 +1,770 @@ +## gMock Cheat Sheet + +<!-- GOOGLETEST_CM0019 DO NOT DELETE --> + +<!-- GOOGLETEST_CM0033 DO NOT DELETE --> + +### Defining a Mock Class + +#### Mocking a Normal Class {#MockClass} + +Given + +```cpp +class Foo { + ... + virtual ~Foo(); + virtual int GetSize() const = 0; + virtual string Describe(const char* name) = 0; + virtual string Describe(int type) = 0; + virtual bool Process(Bar elem, int count) = 0; +}; +``` + +(note that `~Foo()` **must** be virtual) we can define its mock as + +```cpp +#include "gmock/gmock.h" + +class MockFoo : public Foo { + ... + MOCK_METHOD(int, GetSize, (), (const, override)); + MOCK_METHOD(string, Describe, (const char* name), (override)); + MOCK_METHOD(string, Describe, (int type), (override)); + MOCK_METHOD(bool, Process, (Bar elem, int count), (override)); +}; +``` + +To create a "nice" mock, which ignores all uninteresting calls, a "naggy" mock, +which warns on all uninteresting calls, or a "strict" mock, which treats them as +failures: + +```cpp +using ::testing::NiceMock; +using ::testing::NaggyMock; +using ::testing::StrictMock; + +NiceMock<MockFoo> nice_foo; // The type is a subclass of MockFoo. +NaggyMock<MockFoo> naggy_foo; // The type is a subclass of MockFoo. +StrictMock<MockFoo> strict_foo; // The type is a subclass of MockFoo. +``` + +**Note:** A mock object is currently naggy by default. We may make it nice by +default in the future. + +#### Mocking a Class Template {#MockTemplate} + +Class templates can be mocked just like any class. + +To mock + +```cpp +template <typename Elem> +class StackInterface { + ... + virtual ~StackInterface(); + virtual int GetSize() const = 0; + virtual void Push(const Elem& x) = 0; +}; +``` + +(note that all member functions that are mocked, including `~StackInterface()` +**must** be virtual). + +```cpp +template <typename Elem> +class MockStack : public StackInterface<Elem> { + ... + MOCK_METHOD(int, GetSize, (), (const, override)); + MOCK_METHOD(void, Push, (const Elem& x), (override)); +}; +``` + +#### Specifying Calling Conventions for Mock Functions + +If your mock function doesn't use the default calling convention, you can +specify it by adding `Calltype(convention)` to `MOCK_METHOD`'s 4th parameter. +For example, + +```cpp + MOCK_METHOD(bool, Foo, (int n), (Calltype(STDMETHODCALLTYPE))); + MOCK_METHOD(int, Bar, (double x, double y), + (const, Calltype(STDMETHODCALLTYPE))); +``` + +where `STDMETHODCALLTYPE` is defined by `<objbase.h>` on Windows. + +### Using Mocks in Tests {#UsingMocks} + +The typical work flow is: + +1. Import the gMock names you need to use. All gMock symbols are in the + `testing` namespace unless they are macros or otherwise noted. +2. Create the mock objects. +3. Optionally, set the default actions of the mock objects. +4. Set your expectations on the mock objects (How will they be called? What + will they do?). +5. Exercise code that uses the mock objects; if necessary, check the result + using googletest assertions. +6. When a mock object is destructed, gMock automatically verifies that all + expectations on it have been satisfied. + +Here's an example: + +```cpp +using ::testing::Return; // #1 + +TEST(BarTest, DoesThis) { + MockFoo foo; // #2 + + ON_CALL(foo, GetSize()) // #3 + .WillByDefault(Return(1)); + // ... other default actions ... + + EXPECT_CALL(foo, Describe(5)) // #4 + .Times(3) + .WillRepeatedly(Return("Category 5")); + // ... other expectations ... + + EXPECT_EQ("good", MyProductionFunction(&foo)); // #5 +} // #6 +``` + +### Setting Default Actions {#OnCall} + +gMock has a **built-in default action** for any function that returns `void`, +`bool`, a numeric value, or a pointer. In C++11, it will additionally returns +the default-constructed value, if one exists for the given type. + +To customize the default action for functions with return type *`T`*: + +```cpp +using ::testing::DefaultValue; + +// Sets the default value to be returned. T must be CopyConstructible. +DefaultValue<T>::Set(value); +// Sets a factory. Will be invoked on demand. T must be MoveConstructible. +// T MakeT(); +DefaultValue<T>::SetFactory(&MakeT); +// ... use the mocks ... +// Resets the default value. +DefaultValue<T>::Clear(); +``` + +Example usage: + +```cpp + // Sets the default action for return type std::unique_ptr<Buzz> to + // creating a new Buzz every time. + DefaultValue<std::unique_ptr<Buzz>>::SetFactory( + [] { return MakeUnique<Buzz>(AccessLevel::kInternal); }); + + // When this fires, the default action of MakeBuzz() will run, which + // will return a new Buzz object. + EXPECT_CALL(mock_buzzer_, MakeBuzz("hello")).Times(AnyNumber()); + + auto buzz1 = mock_buzzer_.MakeBuzz("hello"); + auto buzz2 = mock_buzzer_.MakeBuzz("hello"); + EXPECT_NE(nullptr, buzz1); + EXPECT_NE(nullptr, buzz2); + EXPECT_NE(buzz1, buzz2); + + // Resets the default action for return type std::unique_ptr<Buzz>, + // to avoid interfere with other tests. + DefaultValue<std::unique_ptr<Buzz>>::Clear(); +``` + +To customize the default action for a particular method of a specific mock +object, use `ON_CALL()`. `ON_CALL()` has a similar syntax to `EXPECT_CALL()`, +but it is used for setting default behaviors (when you do not require that the +mock method is called). See [here](cook_book.md#UseOnCall) for a more detailed +discussion. + +```cpp +ON_CALL(mock-object, method(matchers)) + .With(multi-argument-matcher) ? + .WillByDefault(action); +``` + +### Setting Expectations {#ExpectCall} + +`EXPECT_CALL()` sets **expectations** on a mock method (How will it be called? +What will it do?): + +```cpp +EXPECT_CALL(mock-object, method (matchers)?) + .With(multi-argument-matcher) ? + .Times(cardinality) ? + .InSequence(sequences) * + .After(expectations) * + .WillOnce(action) * + .WillRepeatedly(action) ? + .RetiresOnSaturation(); ? +``` + +If `(matchers)` is omitted, the expectation is the same as if the matchers were +set to anything matchers (for example, `(_, _, _, _)` for a four-arg method). + +If `Times()` is omitted, the cardinality is assumed to be: + +* `Times(1)` when there is neither `WillOnce()` nor `WillRepeatedly()`; +* `Times(n)` when there are `n` `WillOnce()`s but no `WillRepeatedly()`, where + `n` >= 1; or +* `Times(AtLeast(n))` when there are `n` `WillOnce()`s and a + `WillRepeatedly()`, where `n` >= 0. + +A method with no `EXPECT_CALL()` is free to be invoked *any number of times*, +and the default action will be taken each time. + +### Matchers {#MatcherList} + +<!-- GOOGLETEST_CM0020 DO NOT DELETE --> + +A **matcher** matches a *single* argument. You can use it inside `ON_CALL()` or +`EXPECT_CALL()`, or use it to validate a value directly: + +<!-- mdformat off(github rendering does not support multiline tables) --> +| Matcher | Description | +| :----------------------------------- | :------------------------------------ | +| `EXPECT_THAT(actual_value, matcher)` | Asserts that `actual_value` matches `matcher`. | +| `ASSERT_THAT(actual_value, matcher)` | The same as `EXPECT_THAT(actual_value, matcher)`, except that it generates a **fatal** failure. | +<!-- mdformat on --> + +Built-in matchers (where `argument` is the function argument) are divided into +several categories: + +#### Wildcard + +Matcher | Description +:-------------------------- | :----------------------------------------------- +`_` | `argument` can be any value of the correct type. +`A<type>()` or `An<type>()` | `argument` can be any value of type `type`. + +#### Generic Comparison + +<!-- mdformat off(no multiline tables) --> +| Matcher | Description | +| :--------------------- | :-------------------------------------------------- | +| `Eq(value)` or `value` | `argument == value` | +| `Ge(value)` | `argument >= value` | +| `Gt(value)` | `argument > value` | +| `Le(value)` | `argument <= value` | +| `Lt(value)` | `argument < value` | +| `Ne(value)` | `argument != value` | +| `IsNull()` | `argument` is a `NULL` pointer (raw or smart). | +| `NotNull()` | `argument` is a non-null pointer (raw or smart). | +| `Optional(m)` | `argument` is `optional<>` that contains a value matching `m`. | +| `VariantWith<T>(m)` | `argument` is `variant<>` that holds the alternative of type T with a value matching `m`. | +| `Ref(variable)` | `argument` is a reference to `variable`. | +| `TypedEq<type>(value)` | `argument` has type `type` and is equal to `value`. You may need to use this instead of `Eq(value)` when the mock function is overloaded. | +<!-- mdformat on --> + +Except `Ref()`, these matchers make a *copy* of `value` in case it's modified or +destructed later. If the compiler complains that `value` doesn't have a public +copy constructor, try wrap it in `ByRef()`, e.g. +`Eq(ByRef(non_copyable_value))`. If you do that, make sure `non_copyable_value` +is not changed afterwards, or the meaning of your matcher will be changed. + +#### Floating-Point Matchers {#FpMatchers} + +<!-- mdformat off(no multiline tables) --> +| Matcher | Description | +| :------------------------------- | :--------------------------------- | +| `DoubleEq(a_double)` | `argument` is a `double` value approximately equal to `a_double`, treating two NaNs as unequal. | +| `FloatEq(a_float)` | `argument` is a `float` value approximately equal to `a_float`, treating two NaNs as unequal. | +| `NanSensitiveDoubleEq(a_double)` | `argument` is a `double` value approximately equal to `a_double`, treating two NaNs as equal. | +| `NanSensitiveFloatEq(a_float)` | `argument` is a `float` value approximately equal to `a_float`, treating two NaNs as equal. | +<!-- mdformat on --> + +The above matchers use ULP-based comparison (the same as used in googletest). +They automatically pick a reasonable error bound based on the absolute value of +the expected value. `DoubleEq()` and `FloatEq()` conform to the IEEE standard, +which requires comparing two NaNs for equality to return false. The +`NanSensitive*` version instead treats two NaNs as equal, which is often what a +user wants. + +<!-- mdformat off(no multiline tables) --> +| Matcher | Description | +| :------------------------------------------------ | :----------------------- | +| `DoubleNear(a_double, max_abs_error)` | `argument` is a `double` value close to `a_double` (absolute error <= `max_abs_error`), treating two NaNs as unequal. | +| `FloatNear(a_float, max_abs_error)` | `argument` is a `float` value close to `a_float` (absolute error <= `max_abs_error`), treating two NaNs as unequal. | +| `NanSensitiveDoubleNear(a_double, max_abs_error)` | `argument` is a `double` value close to `a_double` (absolute error <= `max_abs_error`), treating two NaNs as equal. | +| `NanSensitiveFloatNear(a_float, max_abs_error)` | `argument` is a `float` value close to `a_float` (absolute error <= `max_abs_error`), treating two NaNs as equal. | +<!-- mdformat on --> + +#### String Matchers + +The `argument` can be either a C string or a C++ string object: + +<!-- mdformat off(no multiline tables) --> +| Matcher | Description | +| :---------------------- | :------------------------------------------------- | +| `ContainsRegex(string)` | `argument` matches the given regular expression. | +| `EndsWith(suffix)` | `argument` ends with string `suffix`. | +| `HasSubstr(string)` | `argument` contains `string` as a sub-string. | +| `MatchesRegex(string)` | `argument` matches the given regular expression with the match starting at the first character and ending at the last character. | +| `StartsWith(prefix)` | `argument` starts with string `prefix`. | +| `StrCaseEq(string)` | `argument` is equal to `string`, ignoring case. | +| `StrCaseNe(string)` | `argument` is not equal to `string`, ignoring case. | +| `StrEq(string)` | `argument` is equal to `string`. | +| `StrNe(string)` | `argument` is not equal to `string`. | +<!-- mdformat on --> + +`ContainsRegex()` and `MatchesRegex()` take ownership of the `RE` object. They +use the regular expression syntax defined +[here](../../googletest/docs/advanced.md#regular-expression-syntax). +`StrCaseEq()`, `StrCaseNe()`, `StrEq()`, and `StrNe()` work for wide strings as +well. + +#### Container Matchers + +Most STL-style containers support `==`, so you can use `Eq(expected_container)` +or simply `expected_container` to match a container exactly. If you want to +write the elements in-line, match them more flexibly, or get more informative +messages, you can use: + +<!-- mdformat off(no multiline tables) --> +| Matcher | Description | +| :---------------------------------------- | :------------------------------- | +| `BeginEndDistanceIs(m)` | `argument` is a container whose `begin()` and `end()` iterators are separated by a number of increments matching `m`. E.g. `BeginEndDistanceIs(2)` or `BeginEndDistanceIs(Lt(2))`. For containers that define a `size()` method, `SizeIs(m)` may be more efficient. | +| `ContainerEq(container)` | The same as `Eq(container)` except that the failure message also includes which elements are in one container but not the other. | +| `Contains(e)` | `argument` contains an element that matches `e`, which can be either a value or a matcher. | +| `Each(e)` | `argument` is a container where *every* element matches `e`, which can be either a value or a matcher. | +| `ElementsAre(e0, e1, ..., en)` | `argument` has `n + 1` elements, where the *i*-th element matches `ei`, which can be a value or a matcher. | +| `ElementsAreArray({e0, e1, ..., en})`, `ElementsAreArray(a_container)`, `ElementsAreArray(begin, end)`, `ElementsAreArray(array)`, or `ElementsAreArray(array, count)` | The same as `ElementsAre()` except that the expected element values/matchers come from an initializer list, STL-style container, iterator range, or C-style array. | +| `IsEmpty()` | `argument` is an empty container (`container.empty()`). | +| `IsFalse()` | `argument` evaluates to `false` in a Boolean context. | +| `IsSubsetOf({e0, e1, ..., en})`, `IsSubsetOf(a_container)`, `IsSubsetOf(begin, end)`, `IsSubsetOf(array)`, or `IsSubsetOf(array, count)` | `argument` matches `UnorderedElementsAre(x0, x1, ..., xk)` for some subset `{x0, x1, ..., xk}` of the expected matchers. | +| `IsSupersetOf({e0, e1, ..., en})`, `IsSupersetOf(a_container)`, `IsSupersetOf(begin, end)`, `IsSupersetOf(array)`, or `IsSupersetOf(array, count)` | Some subset of `argument` matches `UnorderedElementsAre(`expected matchers`)`. | +| `IsTrue()` | `argument` evaluates to `true` in a Boolean context. | +| `Pointwise(m, container)`, `Pointwise(m, {e0, e1, ..., en})` | `argument` contains the same number of elements as in `container`, and for all i, (the i-th element in `argument`, the i-th element in `container`) match `m`, which is a matcher on 2-tuples. E.g. `Pointwise(Le(), upper_bounds)` verifies that each element in `argument` doesn't exceed the corresponding element in `upper_bounds`. See more detail below. | +| `SizeIs(m)` | `argument` is a container whose size matches `m`. E.g. `SizeIs(2)` or `SizeIs(Lt(2))`. | +| `UnorderedElementsAre(e0, e1, ..., en)` | `argument` has `n + 1` elements, and under *some* permutation of the elements, each element matches an `ei` (for a different `i`), which can be a value or a matcher. | +| `UnorderedElementsAreArray({e0, e1, ..., en})`, `UnorderedElementsAreArray(a_container)`, `UnorderedElementsAreArray(begin, end)`, `UnorderedElementsAreArray(array)`, or `UnorderedElementsAreArray(array, count)` | The same as `UnorderedElementsAre()` except that the expected element values/matchers come from an initializer list, STL-style container, iterator range, or C-style array. | +| `UnorderedPointwise(m, container)`, `UnorderedPointwise(m, {e0, e1, ..., en})` | Like `Pointwise(m, container)`, but ignores the order of elements. | +| `WhenSorted(m)` | When `argument` is sorted using the `<` operator, it matches container matcher `m`. E.g. `WhenSorted(ElementsAre(1, 2, 3))` verifies that `argument` contains elements 1, 2, and 3, ignoring order. | +| `WhenSortedBy(comparator, m)` | The same as `WhenSorted(m)`, except that the given comparator instead of `<` is used to sort `argument`. E.g. `WhenSortedBy(std::greater(), ElementsAre(3, 2, 1))`. | +<!-- mdformat on --> + +**Notes:** + +* These matchers can also match: + 1. a native array passed by reference (e.g. in `Foo(const int (&a)[5])`), + and + 2. an array passed as a pointer and a count (e.g. in `Bar(const T* buffer, + int len)` -- see [Multi-argument Matchers](#MultiArgMatchers)). +* The array being matched may be multi-dimensional (i.e. its elements can be + arrays). +* `m` in `Pointwise(m, ...)` should be a matcher for `::std::tuple<T, U>` + where `T` and `U` are the element type of the actual container and the + expected container, respectively. For example, to compare two `Foo` + containers where `Foo` doesn't support `operator==`, one might write: + + ```cpp + using ::std::get; + MATCHER(FooEq, "") { + return std::get<0>(arg).Equals(std::get<1>(arg)); + } + ... + EXPECT_THAT(actual_foos, Pointwise(FooEq(), expected_foos)); + ``` + +#### Member Matchers + +<!-- mdformat off(no multiline tables) --> +| Matcher | Description | +| :------------------------------ | :----------------------------------------- | +| `Field(&class::field, m)` | `argument.field` (or `argument->field` when `argument` is a plain pointer) matches matcher `m`, where `argument` is an object of type _class_. | +| `Key(e)` | `argument.first` matches `e`, which can be either a value or a matcher. E.g. `Contains(Key(Le(5)))` can verify that a `map` contains a key `<= 5`. | +| `Pair(m1, m2)` | `argument` is an `std::pair` whose `first` field matches `m1` and `second` field matches `m2`. | +| `Property(&class::property, m)` | `argument.property()` (or `argument->property()` when `argument` is a plain pointer) matches matcher `m`, where `argument` is an object of type _class_. | +<!-- mdformat on --> + +#### Matching the Result of a Function, Functor, or Callback + +<!-- mdformat off(no multiline tables) --> +| Matcher | Description | +| :--------------- | :------------------------------------------------ | +| `ResultOf(f, m)` | `f(argument)` matches matcher `m`, where `f` is a function or functor. | +<!-- mdformat on --> + +#### Pointer Matchers + +<!-- mdformat off(no multiline tables) --> +| Matcher | Description | +| :------------------------ | :---------------------------------------------- | +| `Pointee(m)` | `argument` (either a smart pointer or a raw pointer) points to a value that matches matcher `m`. | +| `WhenDynamicCastTo<T>(m)` | when `argument` is passed through `dynamic_cast<T>()`, it matches matcher `m`. | +<!-- mdformat on --> + +<!-- GOOGLETEST_CM0026 DO NOT DELETE --> + +<!-- GOOGLETEST_CM0027 DO NOT DELETE --> + +#### Multi-argument Matchers {#MultiArgMatchers} + +Technically, all matchers match a *single* value. A "multi-argument" matcher is +just one that matches a *tuple*. The following matchers can be used to match a +tuple `(x, y)`: + +Matcher | Description +:------ | :---------- +`Eq()` | `x == y` +`Ge()` | `x >= y` +`Gt()` | `x > y` +`Le()` | `x <= y` +`Lt()` | `x < y` +`Ne()` | `x != y` + +You can use the following selectors to pick a subset of the arguments (or +reorder them) to participate in the matching: + +<!-- mdformat off(no multiline tables) --> +| Matcher | Description | +| :------------------------- | :---------------------------------------------- | +| `AllArgs(m)` | Equivalent to `m`. Useful as syntactic sugar in `.With(AllArgs(m))`. | +| `Args<N1, N2, ..., Nk>(m)` | The tuple of the `k` selected (using 0-based indices) arguments matches `m`, e.g. `Args<1, 2>(Eq())`. | +<!-- mdformat on --> + +#### Composite Matchers + +You can make a matcher from one or more other matchers: + +<!-- mdformat off(no multiline tables) --> +| Matcher | Description | +| :------------------------------- | :-------------------------------------- | +| `AllOf(m1, m2, ..., mn)` | `argument` matches all of the matchers `m1` to `mn`. | +| `AllOfArray({m0, m1, ..., mn})`, `AllOfArray(a_container)`, `AllOfArray(begin, end)`, `AllOfArray(array)`, or `AllOfArray(array, count)` | The same as `AllOf()` except that the matchers come from an initializer list, STL-style container, iterator range, or C-style array. | +| `AnyOf(m1, m2, ..., mn)` | `argument` matches at least one of the matchers `m1` to `mn`. | +| `AnyOfArray({m0, m1, ..., mn})`, `AnyOfArray(a_container)`, `AnyOfArray(begin, end)`, `AnyOfArray(array)`, or `AnyOfArray(array, count)` | The same as `AnyOf()` except that the matchers come from an initializer list, STL-style container, iterator range, or C-style array. | +| `Not(m)` | `argument` doesn't match matcher `m`. | +<!-- mdformat on --> + +<!-- GOOGLETEST_CM0028 DO NOT DELETE --> + +#### Adapters for Matchers + +<!-- mdformat off(no multiline tables) --> +| Matcher | Description | +| :---------------------- | :------------------------------------ | +| `MatcherCast<T>(m)` | casts matcher `m` to type `Matcher<T>`. | +| `SafeMatcherCast<T>(m)` | [safely casts](cook_book.md#casting-matchers) matcher `m` to type `Matcher<T>`. | +| `Truly(predicate)` | `predicate(argument)` returns something considered by C++ to be true, where `predicate` is a function or functor. | +<!-- mdformat on --> + +`AddressSatisfies(callback)` and `Truly(callback)` take ownership of `callback`, +which must be a permanent callback. + +#### Using Matchers as Predicates {#MatchersAsPredicatesCheat} + +<!-- mdformat off(no multiline tables) --> +| Matcher | Description | +| :---------------------------- | :------------------------------------------ | +| `Matches(m)(value)` | evaluates to `true` if `value` matches `m`. You can use `Matches(m)` alone as a unary functor. | +| `ExplainMatchResult(m, value, result_listener)` | evaluates to `true` if `value` matches `m`, explaining the result to `result_listener`. | +| `Value(value, m)` | evaluates to `true` if `value` matches `m`. | +<!-- mdformat on --> + +#### Defining Matchers + +<!-- mdformat off(no multiline tables) --> +| Matcher | Description | +| :----------------------------------- | :------------------------------------ | +| `MATCHER(IsEven, "") { return (arg % 2) == 0; }` | Defines a matcher `IsEven()` to match an even number. | +| `MATCHER_P(IsDivisibleBy, n, "") { *result_listener << "where the remainder is " << (arg % n); return (arg % n) == 0; }` | Defines a macher `IsDivisibleBy(n)` to match a number divisible by `n`. | +| `MATCHER_P2(IsBetween, a, b, std::string(negation ? "isn't" : "is") + " between " + PrintToString(a) + " and " + PrintToString(b)) { return a <= arg && arg <= b; }` | Defines a matcher `IsBetween(a, b)` to match a value in the range [`a`, `b`]. | +<!-- mdformat on --> + +**Notes:** + +1. The `MATCHER*` macros cannot be used inside a function or class. +2. The matcher body must be *purely functional* (i.e. it cannot have any side + effect, and the result must not depend on anything other than the value + being matched and the matcher parameters). +3. You can use `PrintToString(x)` to convert a value `x` of any type to a + string. + +### Actions {#ActionList} + +**Actions** specify what a mock function should do when invoked. + +#### Returning a Value + +<!-- mdformat off(no multiline tables) --> +| | | +| :-------------------------- | :-------------------------------------------- | +| `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 <i>at the time the expectation is set</i>, 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. | +<!-- mdformat on --> + +#### Side Effects + +<!-- mdformat off(no multiline tables) --> +| | | +| :--------------------------------- | :-------------------------------------- | +| `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. | +<!-- mdformat on --> + +#### Using a Function, Functor, or Lambda as an Action + +In the following, by "callable" we mean a free function, `std::function`, +functor, or lambda. + +<!-- mdformat off(no multiline tables) --> +| | | +| :---------------------------------- | :------------------------------------- | +| `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. | +<!-- mdformat on --> + +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`: + +```cpp +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. + +```cpp + 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 `ByRef()`. For example, + +```cpp +using ::testing::ByRef; +using ::testing::InvokeArgument; +... +InvokeArgument<2>(5, string("Hi"), ByRef(foo)) +``` + +calls the mock function's #2 argument, passing to it `5` and `string("Hi")` by +value, and `foo` by reference. + +#### Default Action + +<!-- mdformat off(no multiline tables) --> +| Matcher | Description | +| :------------ | :----------------------------------------------------- | +| `DoDefault()` | Do the default action (specified by `ON_CALL()` or the built-in one). | +<!-- mdformat on --> + +**Note:** due to technical reasons, `DoDefault()` cannot be used inside a +composite action - trying to do so will result in a run-time error. + +<!-- GOOGLETEST_CM0032 DO NOT DELETE --> + +#### Composite Actions + +<!-- mdformat off(no multiline tables) --> +| | | +| :----------------------------- | :------------------------------------------ | +| `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. | +| `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. | +<!-- mdformat on --> + +#### Defining Actions + +<table border="1" cellspacing="0" cellpadding="1"> + <tr> + <td>`struct SumAction {` <br> +  `template <typename T>` <br> +  `T operator()(T x, Ty) { return x + y; }` <br> + `};` + </td> + <td> Defines a generic functor that can be used as an action summing its + arguments. </td> </tr> + <tr> + </tr> +</table> + +<!-- mdformat off(no multiline tables) --> +| | | +| :--------------------------------- | :-------------------------------------- | +| `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`. | +<!-- mdformat on --> + +The `ACTION*` macros cannot be used inside a function or class. + +### Cardinalities {#CardinalityList} + +These are used in `Times()` to specify how many times a mock function will be +called: + +<!-- mdformat off(no multiline tables) --> +| | | +| :---------------- | :----------------------------------------------------- | +| `AnyNumber()` | The function can be called any number of times. | +| `AtLeast(n)` | The call is expected at least `n` times. | +| `AtMost(n)` | The call is expected at most `n` times. | +| `Between(m, n)` | The call is expected between `m` and `n` (inclusive) times. | +| `Exactly(n) or n` | The call is expected exactly `n` times. In particular, the call should never happen when `n` is 0. | +<!-- mdformat on --> + +### Expectation Order + +By default, the expectations can be matched in *any* order. If some or all +expectations must be matched in a given order, there are two ways to specify it. +They can be used either independently or together. + +#### The After Clause {#AfterClause} + +```cpp +using ::testing::Expectation; +... +Expectation init_x = EXPECT_CALL(foo, InitX()); +Expectation init_y = EXPECT_CALL(foo, InitY()); +EXPECT_CALL(foo, Bar()) + .After(init_x, init_y); +``` + +says that `Bar()` can be called only after both `InitX()` and `InitY()` have +been called. + +If you don't know how many pre-requisites an expectation has when you write it, +you can use an `ExpectationSet` to collect them: + +```cpp +using ::testing::ExpectationSet; +... +ExpectationSet all_inits; +for (int i = 0; i < element_count; i++) { + all_inits += EXPECT_CALL(foo, InitElement(i)); +} +EXPECT_CALL(foo, Bar()) + .After(all_inits); +``` + +says that `Bar()` can be called only after all elements have been initialized +(but we don't care about which elements get initialized before the others). + +Modifying an `ExpectationSet` after using it in an `.After()` doesn't affect the +meaning of the `.After()`. + +#### Sequences {#UsingSequences} + +When you have a long chain of sequential expectations, it's easier to specify +the order using **sequences**, which don't require you to given each expectation +in the chain a different name. *All expected calls* in the same sequence must +occur in the order they are specified. + +```cpp +using ::testing::Return; +using ::testing::Sequence; +Sequence s1, s2; +... +EXPECT_CALL(foo, Reset()) + .InSequence(s1, s2) + .WillOnce(Return(true)); +EXPECT_CALL(foo, GetSize()) + .InSequence(s1) + .WillOnce(Return(1)); +EXPECT_CALL(foo, Describe(A<const char*>())) + .InSequence(s2) + .WillOnce(Return("dummy")); +``` + +says that `Reset()` must be called before *both* `GetSize()` *and* `Describe()`, +and the latter two can occur in any order. + +To put many expectations in a sequence conveniently: + +```cpp +using ::testing::InSequence; +{ + InSequence seq; + + EXPECT_CALL(...)...; + EXPECT_CALL(...)...; + ... + EXPECT_CALL(...)...; +} +``` + +says that all expected calls in the scope of `seq` must occur in strict order. +The name `seq` is irrelevant. + +### Verifying and Resetting a Mock + +gMock will verify the expectations on a mock object when it is destructed, or +you can do it earlier: + +```cpp +using ::testing::Mock; +... +// Verifies and removes the expectations on mock_obj; +// returns true if successful. +Mock::VerifyAndClearExpectations(&mock_obj); +... +// Verifies and removes the expectations on mock_obj; +// also removes the default actions set by ON_CALL(); +// returns true if successful. +Mock::VerifyAndClear(&mock_obj); +``` + +You can also tell gMock that a mock object can be leaked and doesn't need to be +verified: + +```cpp +Mock::AllowLeak(&mock_obj); +``` + +### Mock Classes + +gMock defines a convenient mock class template + +```cpp +class MockFunction<R(A1, ..., An)> { + public: + MOCK_METHOD(R, Call, (A1, ..., An)); +}; +``` + +See this [recipe](cook_book.md#using-check-points) for one application of it. + +### Flags + +<!-- mdformat off(no multiline tables) --> +| Flag | Description | +| :----------------------------- | :---------------------------------------- | +| `--gmock_catch_leaked_mocks=0` | Don't report leaked mock objects as failures. | +| `--gmock_verbose=LEVEL` | Sets the default verbosity level (`info`, `warning`, or `error`) of Google Mock messages. | +<!-- mdformat on --> |