ceph/src/googletest/googlemock/docs/CheatSheet.md

   1
   2
   3 # Defining a Mock Class #
   4
   5 ## Mocking a Normal Class ##
   6
   7 Given
   8 ```
   9 class Foo {
  10   ...
  11   virtual ~Foo();
  12   virtual int GetSize() const = 0;
  13   virtual string Describe(const char* name) = 0;
  14   virtual string Describe(int type) = 0;
  15   virtual bool Process(Bar elem, int count) = 0;
  16 };
  17 ```
  18 (note that `~Foo()` **must** be virtual) we can define its mock as
  19 ```
  20 #include "gmock/gmock.h"
  21
  22 class MockFoo : public Foo {
  23   MOCK_CONST_METHOD0(GetSize, int());
  24   MOCK_METHOD1(Describe, string(const char* name));
  25   MOCK_METHOD1(Describe, string(int type));
  26   MOCK_METHOD2(Process, bool(Bar elem, int count));
  27 };
  28 ```
  29
  30 To create a "nice" mock object which ignores all uninteresting calls,
  31 or a "strict" mock object, which treats them as failures:
  32 ```
  33 NiceMock<MockFoo> nice_foo;     // The type is a subclass of MockFoo.
  34 StrictMock<MockFoo> strict_foo; // The type is a subclass of MockFoo.
  35 ```
  36
  37 ## Mocking a Class Template ##
  38
  39 To mock
  40 ```
  41 template <typename Elem>
  42 class StackInterface {
  43  public:
  44   ...
  45   virtual ~StackInterface();
  46   virtual int GetSize() const = 0;
  47   virtual void Push(const Elem& x) = 0;
  48 };
  49 ```
  50 (note that `~StackInterface()` **must** be virtual) just append `_T` to the `MOCK_*` macros:
  51 ```
  52 template <typename Elem>
  53 class MockStack : public StackInterface<Elem> {
  54  public:
  55   ...
  56   MOCK_CONST_METHOD0_T(GetSize, int());
  57   MOCK_METHOD1_T(Push, void(const Elem& x));
  58 };
  59 ```
  60
  61 ## Specifying Calling Conventions for Mock Functions ##
  62
  63 If your mock function doesn't use the default calling convention, you
  64 can specify it by appending `_WITH_CALLTYPE` to any of the macros
  65 described in the previous two sections and supplying the calling
  66 convention as the first argument to the macro. For example,
  67 ```
  68   MOCK_METHOD_1_WITH_CALLTYPE(STDMETHODCALLTYPE, Foo, bool(int n));
  69   MOCK_CONST_METHOD2_WITH_CALLTYPE(STDMETHODCALLTYPE, Bar, int(double x, double y));
  70 ```
  71 where `STDMETHODCALLTYPE` is defined by `<objbase.h>` on Windows.
  72
  73 # Using Mocks in Tests #
  74
  75 The typical flow is:
  76   1. Import the Google Mock names you need to use. All Google Mock names are in the `testing` namespace unless they are macros or otherwise noted.
  77   1. Create the mock objects.
  78   1. Optionally, set the default actions of the mock objects.
  79   1. Set your expectations on the mock objects (How will they be called? What wil they do?).
  80   1. Exercise code that uses the mock objects; if necessary, check the result using [Google Test](../../googletest/) assertions.
  81   1. When a mock objects is destructed, Google Mock automatically verifies that all expectations on it have been satisfied.
  82
  83 Here is an example:
  84 ```
  85 using ::testing::Return;                            // #1
  86
  87 TEST(BarTest, DoesThis) {
  88   MockFoo foo;                                    // #2
  89
  90   ON_CALL(foo, GetSize())                         // #3
  91       .WillByDefault(Return(1));
  92   // ... other default actions ...
  93
  94   EXPECT_CALL(foo, Describe(5))                   // #4
  95       .Times(3)
  96       .WillRepeatedly(Return("Category 5"));
  97   // ... other expectations ...
  98
  99   EXPECT_EQ("good", MyProductionFunction(&foo));  // #5
 100 }                                                 // #6
 101 ```
 102
 103 # Setting Default Actions #
 104
 105 Google Mock has a **built-in default action** for any function that
 106 returns `void`, `bool`, a numeric value, or a pointer.
 107
 108 To customize the default action for functions with return type `T` globally:
 109 ```
 110 using ::testing::DefaultValue;
 111
 112 // Sets the default value to be returned. T must be CopyConstructible.
 113 DefaultValue<T>::Set(value);
 114 // Sets a factory. Will be invoked on demand. T must be MoveConstructible.
 115 //   T MakeT();
 116 DefaultValue<T>::SetFactory(&MakeT);
 117 // ... use the mocks ...
 118 // Resets the default value.
 119 DefaultValue<T>::Clear();
 120 ```
 121
 122 To customize the default action for a particular method, use `ON_CALL()`:
 123 ```
 124 ON_CALL(mock_object, method(matchers))
 125     .With(multi_argument_matcher)  ?
 126     .WillByDefault(action);
 127 ```
 128
 129 # Setting Expectations #
 130
 131 `EXPECT_CALL()` sets **expectations** on a mock method (How will it be
 132 called? What will it do?):
 133 ```
 134 EXPECT_CALL(mock_object, method(matchers))
 135     .With(multi_argument_matcher)  ?
 136     .Times(cardinality)            ?
 137     .InSequence(sequences)         *
 138     .After(expectations)           *
 139     .WillOnce(action)              *
 140     .WillRepeatedly(action)        ?
 141     .RetiresOnSaturation();        ?
 142 ```
 143
 144 If `Times()` is omitted, the cardinality is assumed to be:
 145
 146   * `Times(1)` when there is neither `WillOnce()` nor `WillRepeatedly()`;
 147   * `Times(n)` when there are `n WillOnce()`s but no `WillRepeatedly()`, where `n` >= 1; or
 148   * `Times(AtLeast(n))` when there are `n WillOnce()`s and a `WillRepeatedly()`, where `n` >= 0.
 149
 150 A method with no `EXPECT_CALL()` is free to be invoked _any number of times_, and the default action will be taken each time.
 151
 152 # Matchers #
 153
 154 A **matcher** matches a _single_ argument.  You can use it inside
 155 `ON_CALL()` or `EXPECT_CALL()`, or use it to validate a value
 156 directly:
 157
 158 | `EXPECT_THAT(value, matcher)` | Asserts that `value` matches `matcher`. |
 159 |:------------------------------|:----------------------------------------|
 160 | `ASSERT_THAT(value, matcher)` | The same as `EXPECT_THAT(value, matcher)`, except that it generates a **fatal** failure. |
 161
 162 Built-in matchers (where `argument` is the function argument) are
 163 divided into several categories:
 164
 165 ## Wildcard ##
 166 |`_`|`argument` can be any value of the correct type.|
 167 |:--|:-----------------------------------------------|
 168 |`A<type>()` or `An<type>()`|`argument` can be any value of type `type`.     |
 169
 170 ## Generic Comparison ##
 171
 172 |`Eq(value)` or `value`|`argument == value`|
 173 |:---------------------|:------------------|
 174 |`Ge(value)`           |`argument >= value`|
 175 |`Gt(value)`           |`argument > value` |
 176 |`Le(value)`           |`argument <= value`|
 177 |`Lt(value)`           |`argument < value` |
 178 |`Ne(value)`           |`argument != value`|
 179 |`IsNull()`            |`argument` is a `NULL` pointer (raw or smart).|
 180 |`NotNull()`           |`argument` is a non-null pointer (raw or smart).|
 181 |`Ref(variable)`       |`argument` is a reference to `variable`.|
 182 |`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.|
 183
 184 Except `Ref()`, these matchers make a _copy_ of `value` in case it's
 185 modified or destructed later. If the compiler complains that `value`
 186 doesn't have a public copy constructor, try wrap it in `ByRef()`,
 187 e.g. `Eq(ByRef(non_copyable_value))`. If you do that, make sure
 188 `non_copyable_value` is not changed afterwards, or the meaning of your
 189 matcher will be changed.
 190
 191 ## Floating-Point Matchers ##
 192
 193 |`DoubleEq(a_double)`|`argument` is a `double` value approximately equal to `a_double`, treating two NaNs as unequal.|
 194 |:-------------------|:----------------------------------------------------------------------------------------------|
 195 |`FloatEq(a_float)`  |`argument` is a `float` value approximately equal to `a_float`, treating two NaNs as unequal.  |
 196 |`NanSensitiveDoubleEq(a_double)`|`argument` is a `double` value approximately equal to `a_double`, treating two NaNs as equal.  |
 197 |`NanSensitiveFloatEq(a_float)`|`argument` is a `float` value approximately equal to `a_float`, treating two NaNs as equal.    |
 198
 199 The above matchers use ULP-based comparison (the same as used in
 200 [Google Test](../../googletest/)). They
 201 automatically pick a reasonable error bound based on the absolute
 202 value of the expected value.  `DoubleEq()` and `FloatEq()` conform to
 203 the IEEE standard, which requires comparing two NaNs for equality to
 204 return false. The `NanSensitive*` version instead treats two NaNs as
 205 equal, which is often what a user wants.
 206
 207 |`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.|
 208 |:------------------------------------|:--------------------------------------------------------------------------------------------------------------------|
 209 |`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.  |
 210 |`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.  |
 211 |`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.    |
 212
 213 ## String Matchers ##
 214
 215 The `argument` can be either a C string or a C++ string object:
 216
 217 |`ContainsRegex(string)`|`argument` matches the given regular expression.|
 218 |:----------------------|:-----------------------------------------------|
 219 |`EndsWith(suffix)`     |`argument` ends with string `suffix`.           |
 220 |`HasSubstr(string)`    |`argument` contains `string` as a sub-string.   |
 221 |`MatchesRegex(string)` |`argument` matches the given regular expression with the match starting at the first character and ending at the last character.|
 222 |`StartsWith(prefix)`   |`argument` starts with string `prefix`.         |
 223 |`StrCaseEq(string)`    |`argument` is equal to `string`, ignoring case. |
 224 |`StrCaseNe(string)`    |`argument` is not equal to `string`, ignoring case.|
 225 |`StrEq(string)`        |`argument` is equal to `string`.                |
 226 |`StrNe(string)`        |`argument` is not equal to `string`.            |
 227
 228 `ContainsRegex()` and `MatchesRegex()` use the regular expression
 229 syntax defined
 230 [here](../../googletest/docs/AdvancedGuide.md#regular-expression-syntax).
 231 `StrCaseEq()`, `StrCaseNe()`, `StrEq()`, and `StrNe()` work for wide
 232 strings as well.
 233
 234 ## Container Matchers ##
 235
 236 Most STL-style containers support `==`, so you can use
 237 `Eq(expected_container)` or simply `expected_container` to match a
 238 container exactly.   If you want to write the elements in-line,
 239 match them more flexibly, or get more informative messages, you can use:
 240
 241 | `ContainerEq(container)` | The same as `Eq(container)` except that the failure message also includes which elements are in one container but not the other. |
 242 |:-------------------------|:---------------------------------------------------------------------------------------------------------------------------------|
 243 | `Contains(e)`            | `argument` contains an element that matches `e`, which can be either a value or a matcher.                                       |
 244 | `Each(e)`                | `argument` is a container where _every_ element matches `e`, which can be either a value or a matcher.                           |
 245 | `ElementsAre(e0, e1, ..., en)` | `argument` has `n + 1` elements, where the i-th element matches `ei`, which can be a value or a matcher. 0 to 10 arguments are allowed. |
 246 | `ElementsAreArray({ e0, e1, ..., en })`, `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, or C-style array. |
 247 | `IsEmpty()`              | `argument` is an empty container (`container.empty()`).                                                                          |
 248 | `Pointwise(m, container)` | `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. |
 249 | `SizeIs(m)`              | `argument` is a container whose size matches `m`. E.g. `SizeIs(2)` or `SizeIs(Lt(2))`.                                           |
 250 | `UnorderedElementsAre(e0, e1, ..., en)` | `argument` has `n + 1` elements, and under some permutation each element matches an `ei` (for a different `i`), which can be a value or a matcher. 0 to 10 arguments are allowed. |
 251 | `UnorderedElementsAreArray({ e0, e1, ..., en })`, `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, or C-style array. |
 252 | `WhenSorted(m)`          | When `argument` is sorted using the `<` operator, it matches container matcher `m`. E.g. `WhenSorted(UnorderedElementsAre(1, 2, 3))` verifies that `argument` contains elements `1`, `2`, and `3`, ignoring order. |
 253 | `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<int>(), ElementsAre(3, 2, 1))`. |
 254
 255 Notes:
 256
 257   * These matchers can also match:
 258     1. a native array passed by reference (e.g. in `Foo(const int (&a)[5])`), and
 259     1. an array passed as a pointer and a count (e.g. in `Bar(const T* buffer, int len)` -- see [Multi-argument Matchers](#Multiargument_Matchers.md)).
 260   * The array being matched may be multi-dimensional (i.e. its elements can be arrays).
 261   * `m` in `Pointwise(m, ...)` should be a matcher for `::testing::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==` but has an `Equals()` method, one might write:
 262
 263 ```
 264 using ::testing::get;
 265 MATCHER(FooEq, "") {
 266   return get<0>(arg).Equals(get<1>(arg));
 267 }
 268 ...
 269 EXPECT_THAT(actual_foos, Pointwise(FooEq(), expected_foos));
 270 ```
 271
 272 ## Member Matchers ##
 273
 274 |`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_.|
 275 |:------------------------|:---------------------------------------------------------------------------------------------------------------------------------------------|
 276 |`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`.|
 277 |`Pair(m1, m2)`           |`argument` is an `std::pair` whose `first` field matches `m1` and `second` field matches `m2`.                                                |
 278 |`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_.|
 279
 280 ## Matching the Result of a Function or Functor ##
 281
 282 |`ResultOf(f, m)`|`f(argument)` matches matcher `m`, where `f` is a function or functor.|
 283 |:---------------|:---------------------------------------------------------------------|
 284
 285 ## Pointer Matchers ##
 286
 287 |`Pointee(m)`|`argument` (either a smart pointer or a raw pointer) points to a value that matches matcher `m`.|
 288 |:-----------|:-----------------------------------------------------------------------------------------------|
 289 |`WhenDynamicCastTo<T>(m)`| when `argument` is passed through `dynamic_cast<T>()`, it matches matcher `m`.                 |
 290
 291 ## Multiargument Matchers ##
 292
 293 Technically, all matchers match a _single_ value. A "multi-argument"
 294 matcher is just one that matches a _tuple_. The following matchers can
 295 be used to match a tuple `(x, y)`:
 296
 297 |`Eq()`|`x == y`|
 298 |:-----|:-------|
 299 |`Ge()`|`x >= y`|
 300 |`Gt()`|`x > y` |
 301 |`Le()`|`x <= y`|
 302 |`Lt()`|`x < y` |
 303 |`Ne()`|`x != y`|
 304
 305 You can use the following selectors to pick a subset of the arguments
 306 (or reorder them) to participate in the matching:
 307
 308 |`AllArgs(m)`|Equivalent to `m`. Useful as syntactic sugar in `.With(AllArgs(m))`.|
 309 |:-----------|:-------------------------------------------------------------------|
 310 |`Args<N1, N2, ..., Nk>(m)`|The tuple of the `k` selected (using 0-based indices) arguments matches `m`, e.g. `Args<1, 2>(Eq())`.|
 311
 312 ## Composite Matchers ##
 313
 314 You can make a matcher from one or more other matchers:
 315
 316 |`AllOf(m1, m2, ..., mn)`|`argument` matches all of the matchers `m1` to `mn`.|
 317 |:-----------------------|:---------------------------------------------------|
 318 |`AnyOf(m1, m2, ..., mn)`|`argument` matches at least one of the matchers `m1` to `mn`.|
 319 |`Not(m)`                |`argument` doesn't match matcher `m`.               |
 320
 321 ## Adapters for Matchers ##
 322
 323 |`MatcherCast<T>(m)`|casts matcher `m` to type `Matcher<T>`.|
 324 |:------------------|:--------------------------------------|
 325 |`SafeMatcherCast<T>(m)`| [safely casts](CookBook.md#casting-matchers) matcher `m` to type `Matcher<T>`. |
 326 |`Truly(predicate)` |`predicate(argument)` returns something considered by C++ to be true, where `predicate` is a function or functor.|
 327
 328 ## Matchers as Predicates ##
 329
 330 |`Matches(m)(value)`|evaluates to `true` if `value` matches `m`. You can use `Matches(m)` alone as a unary functor.|
 331 |:------------------|:---------------------------------------------------------------------------------------------|
 332 |`ExplainMatchResult(m, value, result_listener)`|evaluates to `true` if `value` matches `m`, explaining the result to `result_listener`.       |
 333 |`Value(value, m)`  |evaluates to `true` if `value` matches `m`.                                                   |
 334
 335 ## Defining Matchers ##
 336
 337 | `MATCHER(IsEven, "") { return (arg % 2) == 0; }` | Defines a matcher `IsEven()` to match an even number. |
 338 |:-------------------------------------------------|:------------------------------------------------------|
 339 | `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`. |
 340 | `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`]. |
 341
 342 **Notes:**
 343
 344   1. The `MATCHER*` macros cannot be used inside a function or class.
 345   1. 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).
 346   1. You can use `PrintToString(x)` to convert a value `x` of any type to a string.
 347
 348 ## Matchers as Test Assertions ##
 349
 350 |`ASSERT_THAT(expression, m)`|Generates a [fatal failure](../../googletest/docs/Primer.md#assertions) if the value of `expression` doesn't match matcher `m`.|
 351 |:---------------------------|:----------------------------------------------------------------------------------------------------------------------------------------------|
 352 |`EXPECT_THAT(expression, m)`|Generates a non-fatal failure if the value of `expression` doesn't match matcher `m`.                                                          |
 353
 354 # Actions #
 355
 356 **Actions** specify what a mock function should do when invoked.
 357
 358 ## Returning a Value ##
 359
 360 |`Return()`|Return from a `void` mock function.|
 361 |:---------|:----------------------------------|
 362 |`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.|
 363 |`ReturnArg<N>()`|Return the `N`-th (0-based) argument.|
 364 |`ReturnNew<T>(a1, ..., ak)`|Return `new T(a1, ..., ak)`; a different object is created each time.|
 365 |`ReturnNull()`|Return a null pointer.             |
 366 |`ReturnPointee(ptr)`|Return the value pointed to by `ptr`.|
 367 |`ReturnRef(variable)`|Return a reference to `variable`.  |
 368 |`ReturnRefOfCopy(value)`|Return a reference to a copy of `value`; the copy lives as long as the action.|
 369
 370 ## Side Effects ##
 371
 372 |`Assign(&variable, value)`|Assign `value` to variable.|
 373 |:-------------------------|:--------------------------|
 374 | `DeleteArg<N>()`         | Delete the `N`-th (0-based) argument, which must be a pointer. |
 375 | `SaveArg<N>(pointer)`    | Save the `N`-th (0-based) argument to `*pointer`. |
 376 | `SaveArgPointee<N>(pointer)` | Save the value pointed to by the `N`-th (0-based) argument to `*pointer`. |
 377 | `SetArgReferee<N>(value)` |   Assign value to the variable referenced by the `N`-th (0-based) argument. |
 378 |`SetArgPointee<N>(value)` |Assign `value` to the variable pointed by the `N`-th (0-based) argument.|
 379 |`SetArgumentPointee<N>(value)`|Same as `SetArgPointee<N>(value)`. Deprecated. Will be removed in v1.7.0.|
 380 |`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.|
 381 |`SetErrnoAndReturn(error, value)`|Set `errno` to `error` and return `value`.|
 382 |`Throw(exception)`        |Throws the given exception, which can be any copyable value. Available since v1.1.0.|
 383
 384 ## Using a Function or a Functor as an Action ##
 385
 386 |`Invoke(f)`|Invoke `f` with the arguments passed to the mock function, where `f` can be a global/static function or a functor.|
 387 |:----------|:-----------------------------------------------------------------------------------------------------------------|
 388 |`Invoke(object_pointer, &class::method)`|Invoke the {method on the object with the arguments passed to the mock function.                                  |
 389 |`InvokeWithoutArgs(f)`|Invoke `f`, which can be a global/static function or a functor. `f` must take no arguments.                       |
 390 |`InvokeWithoutArgs(object_pointer, &class::method)`|Invoke the method on the object, which takes no arguments.                                                        |
 391 |`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.|
 392
 393 The return value of the invoked function is used as the return value
 394 of the action.
 395
 396 When defining a function or functor to be used with `Invoke*()`, you can declare any unused parameters as `Unused`:
 397 ```
 398   double Distance(Unused, double x, double y) { return sqrt(x*x + y*y); }
 399   ...
 400   EXPECT_CALL(mock, Foo("Hi", _, _)).WillOnce(Invoke(Distance));
 401 ```
 402
 403 In `InvokeArgument<N>(...)`, if an argument needs to be passed by reference, wrap it inside `ByRef()`. For example,
 404 ```
 405   InvokeArgument<2>(5, string("Hi"), ByRef(foo))
 406 ```
 407 calls the mock function's #2 argument, passing to it `5` and `string("Hi")` by value, and `foo` by reference.
 408
 409 ## Default Action ##
 410
 411 |`DoDefault()`|Do the default action (specified by `ON_CALL()` or the built-in one).|
 412 |:------------|:--------------------------------------------------------------------|
 413
 414 **Note:** due to technical reasons, `DoDefault()` cannot be used inside  a composite action - trying to do so will result in a run-time error.
 415
 416 ## Composite Actions ##
 417
 418 |`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. |
 419 |:-----------------------|:-----------------------------------------------------------------------------------------------------------------------------|
 420 |`IgnoreResult(a)`       |Perform action `a` and ignore its result. `a` must not return void.                                                           |
 421 |`WithArg<N>(a)`         |Pass the `N`-th (0-based) argument of the mock function to action `a` and perform it.                                         |
 422 |`WithArgs<N1, N2, ..., Nk>(a)`|Pass the selected (0-based) arguments of the mock function to action `a` and perform it.                                      |
 423 |`WithoutArgs(a)`        |Perform action `a` without any arguments.                                                                                     |
 424
 425 ## Defining Actions ##
 426
 427 | `ACTION(Sum) { return arg0 + arg1; }` | Defines an action `Sum()` to return the sum of the mock function's argument #0 and #1. |
 428 |:--------------------------------------|:---------------------------------------------------------------------------------------|
 429 | `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`. |
 430 | `ACTION_Pk(Foo, p1, ..., pk) { statements; }` | Defines a parameterized action `Foo(p1, ..., pk)` to execute the given `statements`.   |
 431
 432 The `ACTION*` macros cannot be used inside a function or class.
 433
 434 # Cardinalities #
 435
 436 These are used in `Times()` to specify how many times a mock function will be called:
 437
 438 |`AnyNumber()`|The function can be called any number of times.|
 439 |:------------|:----------------------------------------------|
 440 |`AtLeast(n)` |The call is expected at least `n` times.       |
 441 |`AtMost(n)`  |The call is expected at most `n` times.        |
 442 |`Between(m, n)`|The call is expected between `m` and `n` (inclusive) times.|
 443 |`Exactly(n) or n`|The call is expected exactly `n` times. In particular, the call should never happen when `n` is 0.|
 444
 445 # Expectation Order #
 446
 447 By default, the expectations can be matched in _any_ order.  If some
 448 or all expectations must be matched in a given order, there are two
 449 ways to specify it.  They can be used either independently or
 450 together.
 451
 452 ## The After Clause ##
 453
 454 ```
 455 using ::testing::Expectation;
 456 ...
 457 Expectation init_x = EXPECT_CALL(foo, InitX());
 458 Expectation init_y = EXPECT_CALL(foo, InitY());
 459 EXPECT_CALL(foo, Bar())
 460     .After(init_x, init_y);
 461 ```
 462 says that `Bar()` can be called only after both `InitX()` and
 463 `InitY()` have been called.
 464
 465 If you don't know how many pre-requisites an expectation has when you
 466 write it, you can use an `ExpectationSet` to collect them:
 467
 468 ```
 469 using ::testing::ExpectationSet;
 470 ...
 471 ExpectationSet all_inits;
 472 for (int i = 0; i < element_count; i++) {
 473   all_inits += EXPECT_CALL(foo, InitElement(i));
 474 }
 475 EXPECT_CALL(foo, Bar())
 476     .After(all_inits);
 477 ```
 478 says that `Bar()` can be called only after all elements have been
 479 initialized (but we don't care about which elements get initialized
 480 before the others).
 481
 482 Modifying an `ExpectationSet` after using it in an `.After()` doesn't
 483 affect the meaning of the `.After()`.
 484
 485 ## Sequences ##
 486
 487 When you have a long chain of sequential expectations, it's easier to
 488 specify the order using **sequences**, which don't require you to given
 489 each expectation in the chain a different name.  <i>All expected<br>
 490 calls</i> in the same sequence must occur in the order they are
 491 specified.
 492
 493 ```
 494 using ::testing::Sequence;
 495 Sequence s1, s2;
 496 ...
 497 EXPECT_CALL(foo, Reset())
 498     .InSequence(s1, s2)
 499     .WillOnce(Return(true));
 500 EXPECT_CALL(foo, GetSize())
 501     .InSequence(s1)
 502     .WillOnce(Return(1));
 503 EXPECT_CALL(foo, Describe(A<const char*>()))
 504     .InSequence(s2)
 505     .WillOnce(Return("dummy"));
 506 ```
 507 says that `Reset()` must be called before _both_ `GetSize()` _and_
 508 `Describe()`, and the latter two can occur in any order.
 509
 510 To put many expectations in a sequence conveniently:
 511 ```
 512 using ::testing::InSequence;
 513 {
 514   InSequence dummy;
 515
 516   EXPECT_CALL(...)...;
 517   EXPECT_CALL(...)...;
 518   ...
 519   EXPECT_CALL(...)...;
 520 }
 521 ```
 522 says that all expected calls in the scope of `dummy` must occur in
 523 strict order. The name `dummy` is irrelevant.)
 524
 525 # Verifying and Resetting a Mock #
 526
 527 Google Mock will verify the expectations on a mock object when it is destructed, or you can do it earlier:
 528 ```
 529 using ::testing::Mock;
 530 ...
 531 // Verifies and removes the expectations on mock_obj;
 532 // returns true iff successful.
 533 Mock::VerifyAndClearExpectations(&mock_obj);
 534 ...
 535 // Verifies and removes the expectations on mock_obj;
 536 // also removes the default actions set by ON_CALL();
 537 // returns true iff successful.
 538 Mock::VerifyAndClear(&mock_obj);
 539 ```
 540
 541 You can also tell Google Mock that a mock object can be leaked and doesn't
 542 need to be verified:
 543 ```
 544 Mock::AllowLeak(&mock_obj);
 545 ```
 546
 547 # Mock Classes #
 548
 549 Google Mock defines a convenient mock class template
 550 ```
 551 class MockFunction<R(A1, ..., An)> {
 552  public:
 553   MOCK_METHODn(Call, R(A1, ..., An));
 554 };
 555 ```
 556 See this [recipe](CookBook.md#using-check-points) for one application of it.
 557
 558 # Flags #
 559
 560 | `--gmock_catch_leaked_mocks=0` | Don't report leaked mock objects as failures. |
 561 |:-------------------------------|:----------------------------------------------|
 562 | `--gmock_verbose=LEVEL`        | Sets the default verbosity level (`info`, `warning`, or `error`) of Google Mock messages. |