ceph/src/googletest/googlemock/docs/v1_7/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](http://code.google.com/p/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 DefaultValue<T>::Set(value);  // Sets the default value to be returned.
 113 // ... use the mocks ...
 114 DefaultValue<T>::Clear();     // Resets the default value.
 115 ```
 116
 117 To customize the default action for a particular method, use `ON_CALL()`:
 118 ```
 119 ON_CALL(mock_object, method(matchers))
 120     .With(multi_argument_matcher)  ?
 121     .WillByDefault(action);
 122 ```
 123
 124 # Setting Expectations #
 125
 126 `EXPECT_CALL()` sets **expectations** on a mock method (How will it be
 127 called? What will it do?):
 128 ```
 129 EXPECT_CALL(mock_object, method(matchers))
 130     .With(multi_argument_matcher)  ?
 131     .Times(cardinality)            ?
 132     .InSequence(sequences)         *
 133     .After(expectations)           *
 134     .WillOnce(action)              *
 135     .WillRepeatedly(action)        ?
 136     .RetiresOnSaturation();        ?
 137 ```
 138
 139 If `Times()` is omitted, the cardinality is assumed to be:
 140
 141   * `Times(1)` when there is neither `WillOnce()` nor `WillRepeatedly()`;
 142   * `Times(n)` when there are `n WillOnce()`s but no `WillRepeatedly()`, where `n` >= 1; or
 143   * `Times(AtLeast(n))` when there are `n WillOnce()`s and a `WillRepeatedly()`, where `n` >= 0.
 144
 145 A method with no `EXPECT_CALL()` is free to be invoked _any number of times_, and the default action will be taken each time.
 146
 147 # Matchers #
 148
 149 A **matcher** matches a _single_ argument.  You can use it inside
 150 `ON_CALL()` or `EXPECT_CALL()`, or use it to validate a value
 151 directly:
 152
 153 | `EXPECT_THAT(value, matcher)` | Asserts that `value` matches `matcher`. |
 154 |:------------------------------|:----------------------------------------|
 155 | `ASSERT_THAT(value, matcher)` | The same as `EXPECT_THAT(value, matcher)`, except that it generates a **fatal** failure. |
 156
 157 Built-in matchers (where `argument` is the function argument) are
 158 divided into several categories:
 159
 160 ## Wildcard ##
 161 |`_`|`argument` can be any value of the correct type.|
 162 |:--|:-----------------------------------------------|
 163 |`A<type>()` or `An<type>()`|`argument` can be any value of type `type`.     |
 164
 165 ## Generic Comparison ##
 166
 167 |`Eq(value)` or `value`|`argument == value`|
 168 |:---------------------|:------------------|
 169 |`Ge(value)`           |`argument >= value`|
 170 |`Gt(value)`           |`argument > value` |
 171 |`Le(value)`           |`argument <= value`|
 172 |`Lt(value)`           |`argument < value` |
 173 |`Ne(value)`           |`argument != value`|
 174 |`IsNull()`            |`argument` is a `NULL` pointer (raw or smart).|
 175 |`NotNull()`           |`argument` is a non-null pointer (raw or smart).|
 176 |`Ref(variable)`       |`argument` is a reference to `variable`.|
 177 |`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.|
 178
 179 Except `Ref()`, these matchers make a _copy_ of `value` in case it's
 180 modified or destructed later. If the compiler complains that `value`
 181 doesn't have a public copy constructor, try wrap it in `ByRef()`,
 182 e.g. `Eq(ByRef(non_copyable_value))`. If you do that, make sure
 183 `non_copyable_value` is not changed afterwards, or the meaning of your
 184 matcher will be changed.
 185
 186 ## Floating-Point Matchers ##
 187
 188 |`DoubleEq(a_double)`|`argument` is a `double` value approximately equal to `a_double`, treating two NaNs as unequal.|
 189 |:-------------------|:----------------------------------------------------------------------------------------------|
 190 |`FloatEq(a_float)`  |`argument` is a `float` value approximately equal to `a_float`, treating two NaNs as unequal.  |
 191 |`NanSensitiveDoubleEq(a_double)`|`argument` is a `double` value approximately equal to `a_double`, treating two NaNs as equal.  |
 192 |`NanSensitiveFloatEq(a_float)`|`argument` is a `float` value approximately equal to `a_float`, treating two NaNs as equal.    |
 193
 194 The above matchers use ULP-based comparison (the same as used in
 195 [Google Test](http://code.google.com/p/googletest/)). They
 196 automatically pick a reasonable error bound based on the absolute
 197 value of the expected value.  `DoubleEq()` and `FloatEq()` conform to
 198 the IEEE standard, which requires comparing two NaNs for equality to
 199 return false. The `NanSensitive*` version instead treats two NaNs as
 200 equal, which is often what a user wants.
 201
 202 |`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.|
 203 |:------------------------------------|:--------------------------------------------------------------------------------------------------------------------|
 204 |`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.  |
 205 |`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.  |
 206 |`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.    |
 207
 208 ## String Matchers ##
 209
 210 The `argument` can be either a C string or a C++ string object:
 211
 212 |`ContainsRegex(string)`|`argument` matches the given regular expression.|
 213 |:----------------------|:-----------------------------------------------|
 214 |`EndsWith(suffix)`     |`argument` ends with string `suffix`.           |
 215 |`HasSubstr(string)`    |`argument` contains `string` as a sub-string.   |
 216 |`MatchesRegex(string)` |`argument` matches the given regular expression with the match starting at the first character and ending at the last character.|
 217 |`StartsWith(prefix)`   |`argument` starts with string `prefix`.         |
 218 |`StrCaseEq(string)`    |`argument` is equal to `string`, ignoring case. |
 219 |`StrCaseNe(string)`    |`argument` is not equal to `string`, ignoring case.|
 220 |`StrEq(string)`        |`argument` is equal to `string`.                |
 221 |`StrNe(string)`        |`argument` is not equal to `string`.            |
 222
 223 `ContainsRegex()` and `MatchesRegex()` use the regular expression
 224 syntax defined
 225 [here](http://code.google.com/p/googletest/wiki/AdvancedGuide#Regular_Expression_Syntax).
 226 `StrCaseEq()`, `StrCaseNe()`, `StrEq()`, and `StrNe()` work for wide
 227 strings as well.
 228
 229 ## Container Matchers ##
 230
 231 Most STL-style containers support `==`, so you can use
 232 `Eq(expected_container)` or simply `expected_container` to match a
 233 container exactly.   If you want to write the elements in-line,
 234 match them more flexibly, or get more informative messages, you can use:
 235
 236 | `ContainerEq(container)` | The same as `Eq(container)` except that the failure message also includes which elements are in one container but not the other. |
 237 |:-------------------------|:---------------------------------------------------------------------------------------------------------------------------------|
 238 | `Contains(e)`            | `argument` contains an element that matches `e`, which can be either a value or a matcher.                                       |
 239 | `Each(e)`                | `argument` is a container where _every_ element matches `e`, which can be either a value or a matcher.                           |
 240 | `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. |
 241 | `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, vector, or C-style array. |
 242 | `IsEmpty()`              | `argument` is an empty container (`container.empty()`).                                                                          |
 243 | `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. |
 244 | `SizeIs(m)`              | `argument` is a container whose size matches `m`. E.g. `SizeIs(2)` or `SizeIs(Lt(2))`.                                           |
 245 | `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. |
 246 | `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, vector, or C-style array. |
 247 | `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. |
 248 | `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))`. |
 249
 250 Notes:
 251
 252   * These matchers can also match:
 253     1. a native array passed by reference (e.g. in `Foo(const int (&a)[5])`), and
 254     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)).
 255   * The array being matched may be multi-dimensional (i.e. its elements can be arrays).
 256   * `m` in `Pointwise(m, ...)` should be a matcher for `std::tr1::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:
 257
 258 ```
 259 using ::std::tr1::get;
 260 MATCHER(FooEq, "") {
 261   return get<0>(arg).Equals(get<1>(arg));
 262 }
 263 ...
 264 EXPECT_THAT(actual_foos, Pointwise(FooEq(), expected_foos));
 265 ```
 266
 267 ## Member Matchers ##
 268
 269 |`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_.|
 270 |:------------------------|:---------------------------------------------------------------------------------------------------------------------------------------------|
 271 |`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`.|
 272 |`Pair(m1, m2)`           |`argument` is an `std::pair` whose `first` field matches `m1` and `second` field matches `m2`.                                                |
 273 |`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_.|
 274
 275 ## Matching the Result of a Function or Functor ##
 276
 277 |`ResultOf(f, m)`|`f(argument)` matches matcher `m`, where `f` is a function or functor.|
 278 |:---------------|:---------------------------------------------------------------------|
 279
 280 ## Pointer Matchers ##
 281
 282 |`Pointee(m)`|`argument` (either a smart pointer or a raw pointer) points to a value that matches matcher `m`.|
 283 |:-----------|:-----------------------------------------------------------------------------------------------|
 284
 285 ## Multiargument Matchers ##
 286
 287 Technically, all matchers match a _single_ value. A "multi-argument"
 288 matcher is just one that matches a _tuple_. The following matchers can
 289 be used to match a tuple `(x, y)`:
 290
 291 |`Eq()`|`x == y`|
 292 |:-----|:-------|
 293 |`Ge()`|`x >= y`|
 294 |`Gt()`|`x > y` |
 295 |`Le()`|`x <= y`|
 296 |`Lt()`|`x < y` |
 297 |`Ne()`|`x != y`|
 298
 299 You can use the following selectors to pick a subset of the arguments
 300 (or reorder them) to participate in the matching:
 301
 302 |`AllArgs(m)`|Equivalent to `m`. Useful as syntactic sugar in `.With(AllArgs(m))`.|
 303 |:-----------|:-------------------------------------------------------------------|
 304 |`Args<N1, N2, ..., Nk>(m)`|The tuple of the `k` selected (using 0-based indices) arguments matches `m`, e.g. `Args<1, 2>(Eq())`.|
 305
 306 ## Composite Matchers ##
 307
 308 You can make a matcher from one or more other matchers:
 309
 310 |`AllOf(m1, m2, ..., mn)`|`argument` matches all of the matchers `m1` to `mn`.|
 311 |:-----------------------|:---------------------------------------------------|
 312 |`AnyOf(m1, m2, ..., mn)`|`argument` matches at least one of the matchers `m1` to `mn`.|
 313 |`Not(m)`                |`argument` doesn't match matcher `m`.               |
 314
 315 ## Adapters for Matchers ##
 316
 317 |`MatcherCast<T>(m)`|casts matcher `m` to type `Matcher<T>`.|
 318 |:------------------|:--------------------------------------|
 319 |`SafeMatcherCast<T>(m)`| [safely casts](http://code.google.com/p/googlemock/wiki/V1_7_CookBook#Casting_Matchers) matcher `m` to type `Matcher<T>`. |
 320 |`Truly(predicate)` |`predicate(argument)` returns something considered by C++ to be true, where `predicate` is a function or functor.|
 321
 322 ## Matchers as Predicates ##
 323
 324 |`Matches(m)(value)`|evaluates to `true` if `value` matches `m`. You can use `Matches(m)` alone as a unary functor.|
 325 |:------------------|:---------------------------------------------------------------------------------------------|
 326 |`ExplainMatchResult(m, value, result_listener)`|evaluates to `true` if `value` matches `m`, explaining the result to `result_listener`.       |
 327 |`Value(value, m)`  |evaluates to `true` if `value` matches `m`.                                                   |
 328
 329 ## Defining Matchers ##
 330
 331 | `MATCHER(IsEven, "") { return (arg % 2) == 0; }` | Defines a matcher `IsEven()` to match an even number. |
 332 |:-------------------------------------------------|:------------------------------------------------------|
 333 | `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`. |
 334 | `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`]. |
 335
 336 **Notes:**
 337
 338   1. The `MATCHER*` macros cannot be used inside a function or class.
 339   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).
 340   1. You can use `PrintToString(x)` to convert a value `x` of any type to a string.
 341
 342 ## Matchers as Test Assertions ##
 343
 344 |`ASSERT_THAT(expression, m)`|Generates a [fatal failure](http://code.google.com/p/googletest/wiki/Primer#Assertions) if the value of `expression` doesn't match matcher `m`.|
 345 |:---------------------------|:----------------------------------------------------------------------------------------------------------------------------------------------|
 346 |`EXPECT_THAT(expression, m)`|Generates a non-fatal failure if the value of `expression` doesn't match matcher `m`.                                                          |
 347
 348 # Actions #
 349
 350 **Actions** specify what a mock function should do when invoked.
 351
 352 ## Returning a Value ##
 353
 354 |`Return()`|Return from a `void` mock function.|
 355 |:---------|:----------------------------------|
 356 |`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.|
 357 |`ReturnArg<N>()`|Return the `N`-th (0-based) argument.|
 358 |`ReturnNew<T>(a1, ..., ak)`|Return `new T(a1, ..., ak)`; a different object is created each time.|
 359 |`ReturnNull()`|Return a null pointer.             |
 360 |`ReturnPointee(ptr)`|Return the value pointed to by `ptr`.|
 361 |`ReturnRef(variable)`|Return a reference to `variable`.  |
 362 |`ReturnRefOfCopy(value)`|Return a reference to a copy of `value`; the copy lives as long as the action.|
 363
 364 ## Side Effects ##
 365
 366 |`Assign(&variable, value)`|Assign `value` to variable.|
 367 |:-------------------------|:--------------------------|
 368 | `DeleteArg<N>()`         | Delete the `N`-th (0-based) argument, which must be a pointer. |
 369 | `SaveArg<N>(pointer)`    | Save the `N`-th (0-based) argument to `*pointer`. |
 370 | `SaveArgPointee<N>(pointer)` | Save the value pointed to by the `N`-th (0-based) argument to `*pointer`. |
 371 | `SetArgReferee<N>(value)` |   Assign value to the variable referenced by the `N`-th (0-based) argument. |
 372 |`SetArgPointee<N>(value)` |Assign `value` to the variable pointed by the `N`-th (0-based) argument.|
 373 |`SetArgumentPointee<N>(value)`|Same as `SetArgPointee<N>(value)`. Deprecated. Will be removed in v1.7.0.|
 374 |`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.|
 375 |`SetErrnoAndReturn(error, value)`|Set `errno` to `error` and return `value`.|
 376 |`Throw(exception)`        |Throws the given exception, which can be any copyable value. Available since v1.1.0.|
 377
 378 ## Using a Function or a Functor as an Action ##
 379
 380 |`Invoke(f)`|Invoke `f` with the arguments passed to the mock function, where `f` can be a global/static function or a functor.|
 381 |:----------|:-----------------------------------------------------------------------------------------------------------------|
 382 |`Invoke(object_pointer, &class::method)`|Invoke the {method on the object with the arguments passed to the mock function.                                  |
 383 |`InvokeWithoutArgs(f)`|Invoke `f`, which can be a global/static function or a functor. `f` must take no arguments.                       |
 384 |`InvokeWithoutArgs(object_pointer, &class::method)`|Invoke the method on the object, which takes no arguments.                                                        |
 385 |`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.|
 386
 387 The return value of the invoked function is used as the return value
 388 of the action.
 389
 390 When defining a function or functor to be used with `Invoke*()`, you can declare any unused parameters as `Unused`:
 391 ```
 392   double Distance(Unused, double x, double y) { return sqrt(x*x + y*y); }
 393   ...
 394   EXPECT_CALL(mock, Foo("Hi", _, _)).WillOnce(Invoke(Distance));
 395 ```
 396
 397 In `InvokeArgument<N>(...)`, if an argument needs to be passed by reference, wrap it inside `ByRef()`. For example,
 398 ```
 399   InvokeArgument<2>(5, string("Hi"), ByRef(foo))
 400 ```
 401 calls the mock function's #2 argument, passing to it `5` and `string("Hi")` by value, and `foo` by reference.
 402
 403 ## Default Action ##
 404
 405 |`DoDefault()`|Do the default action (specified by `ON_CALL()` or the built-in one).|
 406 |:------------|:--------------------------------------------------------------------|
 407
 408 **Note:** due to technical reasons, `DoDefault()` cannot be used inside  a composite action - trying to do so will result in a run-time error.
 409
 410 ## Composite Actions ##
 411
 412 |`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. |
 413 |:-----------------------|:-----------------------------------------------------------------------------------------------------------------------------|
 414 |`IgnoreResult(a)`       |Perform action `a` and ignore its result. `a` must not return void.                                                           |
 415 |`WithArg<N>(a)`         |Pass the `N`-th (0-based) argument of the mock function to action `a` and perform it.                                         |
 416 |`WithArgs<N1, N2, ..., Nk>(a)`|Pass the selected (0-based) arguments of the mock function to action `a` and perform it.                                      |
 417 |`WithoutArgs(a)`        |Perform action `a` without any arguments.                                                                                     |
 418
 419 ## Defining Actions ##
 420
 421 | `ACTION(Sum) { return arg0 + arg1; }` | Defines an action `Sum()` to return the sum of the mock function's argument #0 and #1. |
 422 |:--------------------------------------|:---------------------------------------------------------------------------------------|
 423 | `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`. |
 424 | `ACTION_Pk(Foo, p1, ..., pk) { statements; }` | Defines a parameterized action `Foo(p1, ..., pk)` to execute the given `statements`.   |
 425
 426 The `ACTION*` macros cannot be used inside a function or class.
 427
 428 # Cardinalities #
 429
 430 These are used in `Times()` to specify how many times a mock function will be called:
 431
 432 |`AnyNumber()`|The function can be called any number of times.|
 433 |:------------|:----------------------------------------------|
 434 |`AtLeast(n)` |The call is expected at least `n` times.       |
 435 |`AtMost(n)`  |The call is expected at most `n` times.        |
 436 |`Between(m, n)`|The call is expected between `m` and `n` (inclusive) times.|
 437 |`Exactly(n) or n`|The call is expected exactly `n` times. In particular, the call should never happen when `n` is 0.|
 438
 439 # Expectation Order #
 440
 441 By default, the expectations can be matched in _any_ order.  If some
 442 or all expectations must be matched in a given order, there are two
 443 ways to specify it.  They can be used either independently or
 444 together.
 445
 446 ## The After Clause ##
 447
 448 ```
 449 using ::testing::Expectation;
 450 ...
 451 Expectation init_x = EXPECT_CALL(foo, InitX());
 452 Expectation init_y = EXPECT_CALL(foo, InitY());
 453 EXPECT_CALL(foo, Bar())
 454     .After(init_x, init_y);
 455 ```
 456 says that `Bar()` can be called only after both `InitX()` and
 457 `InitY()` have been called.
 458
 459 If you don't know how many pre-requisites an expectation has when you
 460 write it, you can use an `ExpectationSet` to collect them:
 461
 462 ```
 463 using ::testing::ExpectationSet;
 464 ...
 465 ExpectationSet all_inits;
 466 for (int i = 0; i < element_count; i++) {
 467   all_inits += EXPECT_CALL(foo, InitElement(i));
 468 }
 469 EXPECT_CALL(foo, Bar())
 470     .After(all_inits);
 471 ```
 472 says that `Bar()` can be called only after all elements have been
 473 initialized (but we don't care about which elements get initialized
 474 before the others).
 475
 476 Modifying an `ExpectationSet` after using it in an `.After()` doesn't
 477 affect the meaning of the `.After()`.
 478
 479 ## Sequences ##
 480
 481 When you have a long chain of sequential expectations, it's easier to
 482 specify the order using **sequences**, which don't require you to given
 483 each expectation in the chain a different name.  <i>All expected<br>
 484 calls</i> in the same sequence must occur in the order they are
 485 specified.
 486
 487 ```
 488 using ::testing::Sequence;
 489 Sequence s1, s2;
 490 ...
 491 EXPECT_CALL(foo, Reset())
 492     .InSequence(s1, s2)
 493     .WillOnce(Return(true));
 494 EXPECT_CALL(foo, GetSize())
 495     .InSequence(s1)
 496     .WillOnce(Return(1));
 497 EXPECT_CALL(foo, Describe(A<const char*>()))
 498     .InSequence(s2)
 499     .WillOnce(Return("dummy"));
 500 ```
 501 says that `Reset()` must be called before _both_ `GetSize()` _and_
 502 `Describe()`, and the latter two can occur in any order.
 503
 504 To put many expectations in a sequence conveniently:
 505 ```
 506 using ::testing::InSequence;
 507 {
 508   InSequence dummy;
 509
 510   EXPECT_CALL(...)...;
 511   EXPECT_CALL(...)...;
 512   ...
 513   EXPECT_CALL(...)...;
 514 }
 515 ```
 516 says that all expected calls in the scope of `dummy` must occur in
 517 strict order. The name `dummy` is irrelevant.)
 518
 519 # Verifying and Resetting a Mock #
 520
 521 Google Mock will verify the expectations on a mock object when it is destructed, or you can do it earlier:
 522 ```
 523 using ::testing::Mock;
 524 ...
 525 // Verifies and removes the expectations on mock_obj;
 526 // returns true iff successful.
 527 Mock::VerifyAndClearExpectations(&mock_obj);
 528 ...
 529 // Verifies and removes the expectations on mock_obj;
 530 // also removes the default actions set by ON_CALL();
 531 // returns true iff successful.
 532 Mock::VerifyAndClear(&mock_obj);
 533 ```
 534
 535 You can also tell Google Mock that a mock object can be leaked and doesn't
 536 need to be verified:
 537 ```
 538 Mock::AllowLeak(&mock_obj);
 539 ```
 540
 541 # Mock Classes #
 542
 543 Google Mock defines a convenient mock class template
 544 ```
 545 class MockFunction<R(A1, ..., An)> {
 546  public:
 547   MOCK_METHODn(Call, R(A1, ..., An));
 548 };
 549 ```
 550 See this [recipe](http://code.google.com/p/googlemock/wiki/V1_7_CookBook#Using_Check_Points) for one application of it.
 551
 552 # Flags #
 553
 554 | `--gmock_catch_leaked_mocks=0` | Don't report leaked mock objects as failures. |
 555 |:-------------------------------|:----------------------------------------------|
 556 | `--gmock_verbose=LEVEL`        | Sets the default verbosity level (`info`, `warning`, or `error`) of Google Mock messages. |