1## gMock Cheat Sheet 2 3<!-- GOOGLETEST_CM0019 DO NOT DELETE --> 4 5<!-- GOOGLETEST_CM0033 DO NOT DELETE --> 6 7### Defining a Mock Class 8 9#### Mocking a Normal Class {#MockClass} 10 11Given 12 13```cpp 14class Foo { 15 ... 16 virtual ~Foo(); 17 virtual int GetSize() const = 0; 18 virtual string Describe(const char* name) = 0; 19 virtual string Describe(int type) = 0; 20 virtual bool Process(Bar elem, int count) = 0; 21}; 22``` 23 24(note that `~Foo()` **must** be virtual) we can define its mock as 25 26```cpp 27#include "gmock/gmock.h" 28 29class MockFoo : public Foo { 30 ... 31 MOCK_METHOD(int, GetSize, (), (const, override)); 32 MOCK_METHOD(string, Describe, (const char* name), (override)); 33 MOCK_METHOD(string, Describe, (int type), (override)); 34 MOCK_METHOD(bool, Process, (Bar elem, int count), (override)); 35}; 36``` 37 38To create a "nice" mock, which ignores all uninteresting calls, a "naggy" mock, 39which warns on all uninteresting calls, or a "strict" mock, which treats them as 40failures: 41 42```cpp 43using ::testing::NiceMock; 44using ::testing::NaggyMock; 45using ::testing::StrictMock; 46 47NiceMock<MockFoo> nice_foo; // The type is a subclass of MockFoo. 48NaggyMock<MockFoo> naggy_foo; // The type is a subclass of MockFoo. 49StrictMock<MockFoo> strict_foo; // The type is a subclass of MockFoo. 50``` 51 52**Note:** A mock object is currently naggy by default. We may make it nice by 53default in the future. 54 55#### Mocking a Class Template {#MockTemplate} 56 57Class templates can be mocked just like any class. 58 59To mock 60 61```cpp 62template <typename Elem> 63class StackInterface { 64 ... 65 virtual ~StackInterface(); 66 virtual int GetSize() const = 0; 67 virtual void Push(const Elem& x) = 0; 68}; 69``` 70 71(note that all member functions that are mocked, including `~StackInterface()` 72**must** be virtual). 73 74```cpp 75template <typename Elem> 76class MockStack : public StackInterface<Elem> { 77 ... 78 MOCK_METHOD(int, GetSize, (), (const, override)); 79 MOCK_METHOD(void, Push, (const Elem& x), (override)); 80}; 81``` 82 83#### Specifying Calling Conventions for Mock Functions 84 85If your mock function doesn't use the default calling convention, you can 86specify it by adding `Calltype(convention)` to `MOCK_METHOD`'s 4th parameter. 87For example, 88 89```cpp 90 MOCK_METHOD(bool, Foo, (int n), (Calltype(STDMETHODCALLTYPE))); 91 MOCK_METHOD(int, Bar, (double x, double y), 92 (const, Calltype(STDMETHODCALLTYPE))); 93``` 94 95where `STDMETHODCALLTYPE` is defined by `<objbase.h>` on Windows. 96 97### Using Mocks in Tests {#UsingMocks} 98 99The typical work flow is: 100 1011. Import the gMock names you need to use. All gMock symbols are in the 102 `testing` namespace unless they are macros or otherwise noted. 1032. Create the mock objects. 1043. Optionally, set the default actions of the mock objects. 1054. Set your expectations on the mock objects (How will they be called? What 106 will they do?). 1075. Exercise code that uses the mock objects; if necessary, check the result 108 using googletest assertions. 1096. When a mock object is destructed, gMock automatically verifies that all 110 expectations on it have been satisfied. 111 112Here's an example: 113 114```cpp 115using ::testing::Return; // #1 116 117TEST(BarTest, DoesThis) { 118 MockFoo foo; // #2 119 120 ON_CALL(foo, GetSize()) // #3 121 .WillByDefault(Return(1)); 122 // ... other default actions ... 123 124 EXPECT_CALL(foo, Describe(5)) // #4 125 .Times(3) 126 .WillRepeatedly(Return("Category 5")); 127 // ... other expectations ... 128 129 EXPECT_EQ("good", MyProductionFunction(&foo)); // #5 130} // #6 131``` 132 133### Setting Default Actions {#OnCall} 134 135gMock has a **built-in default action** for any function that returns `void`, 136`bool`, a numeric value, or a pointer. In C++11, it will additionally returns 137the default-constructed value, if one exists for the given type. 138 139To customize the default action for functions with return type *`T`*: 140 141```cpp 142using ::testing::DefaultValue; 143 144// Sets the default value to be returned. T must be CopyConstructible. 145DefaultValue<T>::Set(value); 146// Sets a factory. Will be invoked on demand. T must be MoveConstructible. 147// T MakeT(); 148DefaultValue<T>::SetFactory(&MakeT); 149// ... use the mocks ... 150// Resets the default value. 151DefaultValue<T>::Clear(); 152``` 153 154Example usage: 155 156```cpp 157 // Sets the default action for return type std::unique_ptr<Buzz> to 158 // creating a new Buzz every time. 159 DefaultValue<std::unique_ptr<Buzz>>::SetFactory( 160 [] { return MakeUnique<Buzz>(AccessLevel::kInternal); }); 161 162 // When this fires, the default action of MakeBuzz() will run, which 163 // will return a new Buzz object. 164 EXPECT_CALL(mock_buzzer_, MakeBuzz("hello")).Times(AnyNumber()); 165 166 auto buzz1 = mock_buzzer_.MakeBuzz("hello"); 167 auto buzz2 = mock_buzzer_.MakeBuzz("hello"); 168 EXPECT_NE(nullptr, buzz1); 169 EXPECT_NE(nullptr, buzz2); 170 EXPECT_NE(buzz1, buzz2); 171 172 // Resets the default action for return type std::unique_ptr<Buzz>, 173 // to avoid interfere with other tests. 174 DefaultValue<std::unique_ptr<Buzz>>::Clear(); 175``` 176 177To customize the default action for a particular method of a specific mock 178object, use `ON_CALL()`. `ON_CALL()` has a similar syntax to `EXPECT_CALL()`, 179but it is used for setting default behaviors (when you do not require that the 180mock method is called). See [here](cook_book.md#UseOnCall) for a more detailed 181discussion. 182 183```cpp 184ON_CALL(mock-object, method(matchers)) 185 .With(multi-argument-matcher) ? 186 .WillByDefault(action); 187``` 188 189### Setting Expectations {#ExpectCall} 190 191`EXPECT_CALL()` sets **expectations** on a mock method (How will it be called? 192What will it do?): 193 194```cpp 195EXPECT_CALL(mock-object, method (matchers)?) 196 .With(multi-argument-matcher) ? 197 .Times(cardinality) ? 198 .InSequence(sequences) * 199 .After(expectations) * 200 .WillOnce(action) * 201 .WillRepeatedly(action) ? 202 .RetiresOnSaturation(); ? 203``` 204 205For each item above, `?` means it can be used at most once, while `*` means it 206can be used any number of times. 207 208In order to pass, `EXPECT_CALL` must be used before the calls are actually made. 209 210The `(matchers)` is a comma-separated list of matchers that correspond to each 211of the arguments of `method`, and sets the expectation only for calls of 212`method` that matches all of the matchers. 213 214If `(matchers)` is omitted, the expectation is the same as if the matchers were 215set to anything matchers (for example, `(_, _, _, _)` for a four-arg method). 216 217If `Times()` is omitted, the cardinality is assumed to be: 218 219* `Times(1)` when there is neither `WillOnce()` nor `WillRepeatedly()`; 220* `Times(n)` when there are `n` `WillOnce()`s but no `WillRepeatedly()`, where 221 `n` >= 1; or 222* `Times(AtLeast(n))` when there are `n` `WillOnce()`s and a 223 `WillRepeatedly()`, where `n` >= 0. 224 225A method with no `EXPECT_CALL()` is free to be invoked *any number of times*, 226and the default action will be taken each time. 227 228### Matchers {#MatcherList} 229 230<!-- GOOGLETEST_CM0020 DO NOT DELETE --> 231 232A **matcher** matches a *single* argument. You can use it inside `ON_CALL()` or 233`EXPECT_CALL()`, or use it to validate a value directly using two macros: 234 235<!-- mdformat off(github rendering does not support multiline tables) --> 236| Macro | Description | 237| :----------------------------------- | :------------------------------------ | 238| `EXPECT_THAT(actual_value, matcher)` | Asserts that `actual_value` matches `matcher`. | 239| `ASSERT_THAT(actual_value, matcher)` | The same as `EXPECT_THAT(actual_value, matcher)`, except that it generates a **fatal** failure. | 240<!-- mdformat on --> 241 242Built-in matchers (where `argument` is the function argument, e.g. 243`actual_value` in the example above, or when used in the context of 244`EXPECT_CALL(mock_object, method(matchers))`, the arguments of `method`) are 245divided into several categories: 246 247#### Wildcard 248 249Matcher | Description 250:-------------------------- | :----------------------------------------------- 251`_` | `argument` can be any value of the correct type. 252`A<type>()` or `An<type>()` | `argument` can be any value of type `type`. 253 254#### Generic Comparison 255 256<!-- mdformat off(no multiline tables) --> 257| Matcher | Description | 258| :--------------------- | :-------------------------------------------------- | 259| `Eq(value)` or `value` | `argument == value` | 260| `Ge(value)` | `argument >= value` | 261| `Gt(value)` | `argument > value` | 262| `Le(value)` | `argument <= value` | 263| `Lt(value)` | `argument < value` | 264| `Ne(value)` | `argument != value` | 265| `IsFalse()` | `argument` evaluates to `false` in a Boolean context. | 266| `IsTrue()` | `argument` evaluates to `true` in a Boolean context. | 267| `IsNull()` | `argument` is a `NULL` pointer (raw or smart). | 268| `NotNull()` | `argument` is a non-null pointer (raw or smart). | 269| `Optional(m)` | `argument` is `optional<>` that contains a value matching `m`. (For testing whether an `optional<>` is set, check for equality with `nullopt`. You may need to use `Eq(nullopt)` if the inner type doesn't have `==`.)| 270| `VariantWith<T>(m)` | `argument` is `variant<>` that holds the alternative of type T with a value matching `m`. | 271| `Ref(variable)` | `argument` is a reference to `variable`. | 272| `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. | 273<!-- mdformat on --> 274 275Except `Ref()`, these matchers make a *copy* of `value` in case it's modified or 276destructed later. If the compiler complains that `value` doesn't have a public 277copy constructor, try wrap it in `ByRef()`, e.g. 278`Eq(ByRef(non_copyable_value))`. If you do that, make sure `non_copyable_value` 279is not changed afterwards, or the meaning of your matcher will be changed. 280 281`IsTrue` and `IsFalse` are useful when you need to use a matcher, or for types 282that can be explicitly converted to Boolean, but are not implicitly converted to 283Boolean. In other cases, you can use the basic 284[`EXPECT_TRUE` and `EXPECT_FALSE`](../../googletest/docs/primer#basic-assertions) 285assertions. 286 287#### Floating-Point Matchers {#FpMatchers} 288 289<!-- mdformat off(no multiline tables) --> 290| Matcher | Description | 291| :------------------------------- | :--------------------------------- | 292| `DoubleEq(a_double)` | `argument` is a `double` value approximately equal to `a_double`, treating two NaNs as unequal. | 293| `FloatEq(a_float)` | `argument` is a `float` value approximately equal to `a_float`, treating two NaNs as unequal. | 294| `NanSensitiveDoubleEq(a_double)` | `argument` is a `double` value approximately equal to `a_double`, treating two NaNs as equal. | 295| `NanSensitiveFloatEq(a_float)` | `argument` is a `float` value approximately equal to `a_float`, treating two NaNs as equal. | 296| `IsNan()` | `argument` is any floating-point type with a NaN value. | 297<!-- mdformat on --> 298 299The above matchers use ULP-based comparison (the same as used in googletest). 300They automatically pick a reasonable error bound based on the absolute value of 301the expected value. `DoubleEq()` and `FloatEq()` conform to the IEEE standard, 302which requires comparing two NaNs for equality to return false. The 303`NanSensitive*` version instead treats two NaNs as equal, which is often what a 304user wants. 305 306<!-- mdformat off(no multiline tables) --> 307| Matcher | Description | 308| :------------------------------------------------ | :----------------------- | 309| `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. | 310| `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. | 311| `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. | 312| `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. | 313<!-- mdformat on --> 314 315#### String Matchers 316 317The `argument` can be either a C string or a C++ string object: 318 319<!-- mdformat off(no multiline tables) --> 320| Matcher | Description | 321| :---------------------- | :------------------------------------------------- | 322| `ContainsRegex(string)` | `argument` matches the given regular expression. | 323| `EndsWith(suffix)` | `argument` ends with string `suffix`. | 324| `HasSubstr(string)` | `argument` contains `string` as a sub-string. | 325| `MatchesRegex(string)` | `argument` matches the given regular expression with the match starting at the first character and ending at the last character. | 326| `StartsWith(prefix)` | `argument` starts with string `prefix`. | 327| `StrCaseEq(string)` | `argument` is equal to `string`, ignoring case. | 328| `StrCaseNe(string)` | `argument` is not equal to `string`, ignoring case. | 329| `StrEq(string)` | `argument` is equal to `string`. | 330| `StrNe(string)` | `argument` is not equal to `string`. | 331<!-- mdformat on --> 332 333`ContainsRegex()` and `MatchesRegex()` take ownership of the `RE` object. They 334use the regular expression syntax defined 335[here](../../googletest/docs/advanced.md#regular-expression-syntax). All of 336these matchers, except `ContainsRegex()` and `MatchesRegex()` work for wide 337strings as well. 338 339#### Container Matchers 340 341Most STL-style containers support `==`, so you can use `Eq(expected_container)` 342or simply `expected_container` to match a container exactly. If you want to 343write the elements in-line, match them more flexibly, or get more informative 344messages, you can use: 345 346<!-- mdformat off(no multiline tables) --> 347| Matcher | Description | 348| :---------------------------------------- | :------------------------------- | 349| `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. | 350| `ContainerEq(container)` | The same as `Eq(container)` except that the failure message also includes which elements are in one container but not the other. | 351| `Contains(e)` | `argument` contains an element that matches `e`, which can be either a value or a matcher. | 352| `Each(e)` | `argument` is a container where *every* element matches `e`, which can be either a value or a matcher. | 353| `ElementsAre(e0, e1, ..., en)` | `argument` has `n + 1` elements, where the *i*-th element matches `ei`, which can be a value or a matcher. | 354| `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. | 355| `IsEmpty()` | `argument` is an empty container (`container.empty()`). | 356| `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. | 357| `IsSupersetOf({e0, e1, ..., en})`, `IsSupersetOf(a_container)`, `IsSupersetOf(begin, end)`, `IsSupersetOf(array)`, or `IsSupersetOf(array, count)` | Some subset of `argument` matches `UnorderedElementsAre(`expected matchers`)`. | 358| `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. | 359| `SizeIs(m)` | `argument` is a container whose size matches `m`. E.g. `SizeIs(2)` or `SizeIs(Lt(2))`. | 360| `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. | 361| `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. | 362| `UnorderedPointwise(m, container)`, `UnorderedPointwise(m, {e0, e1, ..., en})` | Like `Pointwise(m, container)`, but ignores the order of elements. | 363| `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. | 364| `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))`. | 365<!-- mdformat on --> 366 367**Notes:** 368 369* These matchers can also match: 370 1. a native array passed by reference (e.g. in `Foo(const int (&a)[5])`), 371 and 372 2. an array passed as a pointer and a count (e.g. in `Bar(const T* buffer, 373 int len)` -- see [Multi-argument Matchers](#MultiArgMatchers)). 374* The array being matched may be multi-dimensional (i.e. its elements can be 375 arrays). 376* `m` in `Pointwise(m, ...)` should be a matcher for `::std::tuple<T, U>` 377 where `T` and `U` are the element type of the actual container and the 378 expected container, respectively. For example, to compare two `Foo` 379 containers where `Foo` doesn't support `operator==`, one might write: 380 381 ```cpp 382 using ::std::get; 383 MATCHER(FooEq, "") { 384 return std::get<0>(arg).Equals(std::get<1>(arg)); 385 } 386 ... 387 EXPECT_THAT(actual_foos, Pointwise(FooEq(), expected_foos)); 388 ``` 389 390#### Member Matchers 391 392<!-- mdformat off(no multiline tables) --> 393| Matcher | Description | 394| :------------------------------ | :----------------------------------------- | 395| `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_. | 396| `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`. | 397| `Pair(m1, m2)` | `argument` is an `std::pair` whose `first` field matches `m1` and `second` field matches `m2`. | 398| `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_. | 399<!-- mdformat on --> 400 401#### Matching the Result of a Function, Functor, or Callback 402 403<!-- mdformat off(no multiline tables) --> 404| Matcher | Description | 405| :--------------- | :------------------------------------------------ | 406| `ResultOf(f, m)` | `f(argument)` matches matcher `m`, where `f` is a function or functor. | 407<!-- mdformat on --> 408 409#### Pointer Matchers 410 411<!-- mdformat off(no multiline tables) --> 412| Matcher | Description | 413| :------------------------ | :---------------------------------------------- | 414| `Pointee(m)` | `argument` (either a smart pointer or a raw pointer) points to a value that matches matcher `m`. | 415| `WhenDynamicCastTo<T>(m)` | when `argument` is passed through `dynamic_cast<T>()`, it matches matcher `m`. | 416<!-- mdformat on --> 417 418<!-- GOOGLETEST_CM0026 DO NOT DELETE --> 419 420<!-- GOOGLETEST_CM0027 DO NOT DELETE --> 421 422#### Multi-argument Matchers {#MultiArgMatchers} 423 424Technically, all matchers match a *single* value. A "multi-argument" matcher is 425just one that matches a *tuple*. The following matchers can be used to match a 426tuple `(x, y)`: 427 428Matcher | Description 429:------ | :---------- 430`Eq()` | `x == y` 431`Ge()` | `x >= y` 432`Gt()` | `x > y` 433`Le()` | `x <= y` 434`Lt()` | `x < y` 435`Ne()` | `x != y` 436 437You can use the following selectors to pick a subset of the arguments (or 438reorder them) to participate in the matching: 439 440<!-- mdformat off(no multiline tables) --> 441| Matcher | Description | 442| :------------------------- | :---------------------------------------------- | 443| `AllArgs(m)` | Equivalent to `m`. Useful as syntactic sugar in `.With(AllArgs(m))`. | 444| `Args<N1, N2, ..., Nk>(m)` | The tuple of the `k` selected (using 0-based indices) arguments matches `m`, e.g. `Args<1, 2>(Eq())`. | 445<!-- mdformat on --> 446 447#### Composite Matchers 448 449You can make a matcher from one or more other matchers: 450 451<!-- mdformat off(no multiline tables) --> 452| Matcher | Description | 453| :------------------------------- | :-------------------------------------- | 454| `AllOf(m1, m2, ..., mn)` | `argument` matches all of the matchers `m1` to `mn`. | 455| `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. | 456| `AnyOf(m1, m2, ..., mn)` | `argument` matches at least one of the matchers `m1` to `mn`. | 457| `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. | 458| `Not(m)` | `argument` doesn't match matcher `m`. | 459<!-- mdformat on --> 460 461<!-- GOOGLETEST_CM0028 DO NOT DELETE --> 462 463#### Adapters for Matchers 464 465<!-- mdformat off(no multiline tables) --> 466| Matcher | Description | 467| :---------------------- | :------------------------------------ | 468| `MatcherCast<T>(m)` | casts matcher `m` to type `Matcher<T>`. | 469| `SafeMatcherCast<T>(m)` | [safely casts](cook_book.md#casting-matchers) matcher `m` to type `Matcher<T>`. | 470| `Truly(predicate)` | `predicate(argument)` returns something considered by C++ to be true, where `predicate` is a function or functor. | 471<!-- mdformat on --> 472 473`AddressSatisfies(callback)` and `Truly(callback)` take ownership of `callback`, 474which must be a permanent callback. 475 476#### Using Matchers as Predicates {#MatchersAsPredicatesCheat} 477 478<!-- mdformat off(no multiline tables) --> 479| Matcher | Description | 480| :---------------------------- | :------------------------------------------ | 481| `Matches(m)(value)` | evaluates to `true` if `value` matches `m`. You can use `Matches(m)` alone as a unary functor. | 482| `ExplainMatchResult(m, value, result_listener)` | evaluates to `true` if `value` matches `m`, explaining the result to `result_listener`. | 483| `Value(value, m)` | evaluates to `true` if `value` matches `m`. | 484<!-- mdformat on --> 485 486#### Defining Matchers 487 488<!-- mdformat off(no multiline tables) --> 489| Matcher | Description | 490| :----------------------------------- | :------------------------------------ | 491| `MATCHER(IsEven, "") { return (arg % 2) == 0; }` | Defines a matcher `IsEven()` to match an even number. | 492| `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`. | 493| `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`]. | 494<!-- mdformat on --> 495 496**Notes:** 497 4981. The `MATCHER*` macros cannot be used inside a function or class. 4992. The matcher body must be *purely functional* (i.e. it cannot have any side 500 effect, and the result must not depend on anything other than the value 501 being matched and the matcher parameters). 5023. You can use `PrintToString(x)` to convert a value `x` of any type to a 503 string. 504 505### Actions {#ActionList} 506 507**Actions** specify what a mock function should do when invoked. 508 509#### Returning a Value 510 511<!-- mdformat off(no multiline tables) --> 512| | | 513| :-------------------------------- | :-------------------------------------------- | 514| `Return()` | Return from a `void` mock function. | 515| `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. | 516| `ReturnArg<N>()` | Return the `N`-th (0-based) argument. | 517| `ReturnNew<T>(a1, ..., ak)` | Return `new T(a1, ..., ak)`; a different object is created each time. | 518| `ReturnNull()` | Return a null pointer. | 519| `ReturnPointee(ptr)` | Return the value pointed to by `ptr`. | 520| `ReturnRef(variable)` | Return a reference to `variable`. | 521| `ReturnRefOfCopy(value)` | Return a reference to a copy of `value`; the copy lives as long as the action. | 522| `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. | 523<!-- mdformat on --> 524 525#### Side Effects 526 527<!-- mdformat off(no multiline tables) --> 528| | | 529| :--------------------------------- | :-------------------------------------- | 530| `Assign(&variable, value)` | Assign `value` to variable. | 531| `DeleteArg<N>()` | Delete the `N`-th (0-based) argument, which must be a pointer. | 532| `SaveArg<N>(pointer)` | Save the `N`-th (0-based) argument to `*pointer`. | 533| `SaveArgPointee<N>(pointer)` | Save the value pointed to by the `N`-th (0-based) argument to `*pointer`. | 534| `SetArgReferee<N>(value)` | Assign value to the variable referenced by the `N`-th (0-based) argument. | 535| `SetArgPointee<N>(value)` | Assign `value` to the variable pointed by the `N`-th (0-based) argument. | 536| `SetArgumentPointee<N>(value)` | Same as `SetArgPointee<N>(value)`. Deprecated. Will be removed in v1.7.0. | 537| `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. | 538| `SetErrnoAndReturn(error, value)` | Set `errno` to `error` and return `value`. | 539| `Throw(exception)` | Throws the given exception, which can be any copyable value. Available since v1.1.0. | 540<!-- mdformat on --> 541 542#### Using a Function, Functor, or Lambda as an Action 543 544In the following, by "callable" we mean a free function, `std::function`, 545functor, or lambda. 546 547<!-- mdformat off(no multiline tables) --> 548| | | 549| :---------------------------------- | :------------------------------------- | 550| `f` | Invoke f with the arguments passed to the mock function, where f is a callable. | 551| `Invoke(f)` | Invoke `f` with the arguments passed to the mock function, where `f` can be a global/static function or a functor. | 552| `Invoke(object_pointer, &class::method)` | Invoke the method on the object with the arguments passed to the mock function. | 553| `InvokeWithoutArgs(f)` | Invoke `f`, which can be a global/static function or a functor. `f` must take no arguments. | 554| `InvokeWithoutArgs(object_pointer, &class::method)` | Invoke the method on the object, which takes no arguments. | 555| `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. | 556<!-- mdformat on --> 557 558The return value of the invoked function is used as the return value of the 559action. 560 561When defining a callable to be used with `Invoke*()`, you can declare any unused 562parameters as `Unused`: 563 564```cpp 565using ::testing::Invoke; 566double Distance(Unused, double x, double y) { return sqrt(x*x + y*y); } 567... 568EXPECT_CALL(mock, Foo("Hi", _, _)).WillOnce(Invoke(Distance)); 569``` 570 571`Invoke(callback)` and `InvokeWithoutArgs(callback)` take ownership of 572`callback`, which must be permanent. The type of `callback` must be a base 573callback type instead of a derived one, e.g. 574 575```cpp 576 BlockingClosure* done = new BlockingClosure; 577 ... Invoke(done) ...; // This won't compile! 578 579 Closure* done2 = new BlockingClosure; 580 ... Invoke(done2) ...; // This works. 581``` 582 583In `InvokeArgument<N>(...)`, if an argument needs to be passed by reference, 584wrap it inside `ByRef()`. For example, 585 586```cpp 587using ::testing::ByRef; 588using ::testing::InvokeArgument; 589... 590InvokeArgument<2>(5, string("Hi"), ByRef(foo)) 591``` 592 593calls the mock function's #2 argument, passing to it `5` and `string("Hi")` by 594value, and `foo` by reference. 595 596#### Default Action 597 598<!-- mdformat off(no multiline tables) --> 599| Matcher | Description | 600| :------------ | :----------------------------------------------------- | 601| `DoDefault()` | Do the default action (specified by `ON_CALL()` or the built-in one). | 602<!-- mdformat on --> 603 604**Note:** due to technical reasons, `DoDefault()` cannot be used inside a 605composite action - trying to do so will result in a run-time error. 606 607<!-- GOOGLETEST_CM0032 DO NOT DELETE --> 608 609#### Composite Actions 610 611<!-- mdformat off(no multiline tables) --> 612| | | 613| :----------------------------- | :------------------------------------------ | 614| `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. | 615| `IgnoreResult(a)` | Perform action `a` and ignore its result. `a` must not return void. | 616| `WithArg<N>(a)` | Pass the `N`-th (0-based) argument of the mock function to action `a` and perform it. | 617| `WithArgs<N1, N2, ..., Nk>(a)` | Pass the selected (0-based) arguments of the mock function to action `a` and perform it. | 618| `WithoutArgs(a)` | Perform action `a` without any arguments. | 619<!-- mdformat on --> 620 621#### Defining Actions 622 623<!-- mdformat off(no multiline tables) --> 624| | | 625| :--------------------------------- | :-------------------------------------- | 626| `ACTION(Sum) { return arg0 + arg1; }` | Defines an action `Sum()` to return the sum of the mock function's argument #0 and #1. | 627| `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`. | 628| `ACTION_Pk(Foo, p1, ..., pk) { statements; }` | Defines a parameterized action `Foo(p1, ..., pk)` to execute the given `statements`. | 629<!-- mdformat on --> 630 631The `ACTION*` macros cannot be used inside a function or class. 632 633### Cardinalities {#CardinalityList} 634 635These are used in `Times()` to specify how many times a mock function will be 636called: 637 638<!-- mdformat off(no multiline tables) --> 639| | | 640| :---------------- | :----------------------------------------------------- | 641| `AnyNumber()` | The function can be called any number of times. | 642| `AtLeast(n)` | The call is expected at least `n` times. | 643| `AtMost(n)` | The call is expected at most `n` times. | 644| `Between(m, n)` | The call is expected between `m` and `n` (inclusive) times. | 645| `Exactly(n) or n` | The call is expected exactly `n` times. In particular, the call should never happen when `n` is 0. | 646<!-- mdformat on --> 647 648### Expectation Order 649 650By default, the expectations can be matched in *any* order. If some or all 651expectations must be matched in a given order, there are two ways to specify it. 652They can be used either independently or together. 653 654#### The After Clause {#AfterClause} 655 656```cpp 657using ::testing::Expectation; 658... 659Expectation init_x = EXPECT_CALL(foo, InitX()); 660Expectation init_y = EXPECT_CALL(foo, InitY()); 661EXPECT_CALL(foo, Bar()) 662 .After(init_x, init_y); 663``` 664 665says that `Bar()` can be called only after both `InitX()` and `InitY()` have 666been called. 667 668If you don't know how many pre-requisites an expectation has when you write it, 669you can use an `ExpectationSet` to collect them: 670 671```cpp 672using ::testing::ExpectationSet; 673... 674ExpectationSet all_inits; 675for (int i = 0; i < element_count; i++) { 676 all_inits += EXPECT_CALL(foo, InitElement(i)); 677} 678EXPECT_CALL(foo, Bar()) 679 .After(all_inits); 680``` 681 682says that `Bar()` can be called only after all elements have been initialized 683(but we don't care about which elements get initialized before the others). 684 685Modifying an `ExpectationSet` after using it in an `.After()` doesn't affect the 686meaning of the `.After()`. 687 688#### Sequences {#UsingSequences} 689 690When you have a long chain of sequential expectations, it's easier to specify 691the order using **sequences**, which don't require you to given each expectation 692in the chain a different name. *All expected calls* in the same sequence must 693occur in the order they are specified. 694 695```cpp 696using ::testing::Return; 697using ::testing::Sequence; 698Sequence s1, s2; 699... 700EXPECT_CALL(foo, Reset()) 701 .InSequence(s1, s2) 702 .WillOnce(Return(true)); 703EXPECT_CALL(foo, GetSize()) 704 .InSequence(s1) 705 .WillOnce(Return(1)); 706EXPECT_CALL(foo, Describe(A<const char*>())) 707 .InSequence(s2) 708 .WillOnce(Return("dummy")); 709``` 710 711says that `Reset()` must be called before *both* `GetSize()` *and* `Describe()`, 712and the latter two can occur in any order. 713 714To put many expectations in a sequence conveniently: 715 716```cpp 717using ::testing::InSequence; 718{ 719 InSequence seq; 720 721 EXPECT_CALL(...)...; 722 EXPECT_CALL(...)...; 723 ... 724 EXPECT_CALL(...)...; 725} 726``` 727 728says that all expected calls in the scope of `seq` must occur in strict order. 729The name `seq` is irrelevant. 730 731### Verifying and Resetting a Mock 732 733gMock will verify the expectations on a mock object when it is destructed, or 734you can do it earlier: 735 736```cpp 737using ::testing::Mock; 738... 739// Verifies and removes the expectations on mock_obj; 740// returns true if and only if successful. 741Mock::VerifyAndClearExpectations(&mock_obj); 742... 743// Verifies and removes the expectations on mock_obj; 744// also removes the default actions set by ON_CALL(); 745// returns true if and only if successful. 746Mock::VerifyAndClear(&mock_obj); 747``` 748 749You can also tell gMock that a mock object can be leaked and doesn't need to be 750verified: 751 752```cpp 753Mock::AllowLeak(&mock_obj); 754``` 755 756### Mock Classes 757 758gMock defines a convenient mock class template 759 760```cpp 761class MockFunction<R(A1, ..., An)> { 762 public: 763 MOCK_METHOD(R, Call, (A1, ..., An)); 764}; 765``` 766 767See this [recipe](cook_book.md#using-check-points) for one application of it. 768 769### Flags 770 771<!-- mdformat off(no multiline tables) --> 772| Flag | Description | 773| :----------------------------- | :---------------------------------------- | 774| `--gmock_catch_leaked_mocks=0` | Don't report leaked mock objects as failures. | 775| `--gmock_verbose=LEVEL` | Sets the default verbosity level (`info`, `warning`, or `error`) of Google Mock messages. | 776<!-- mdformat on --> 777