1
2
3# Defining a Mock Class #
4
5## Mocking a Normal Class ##
6
7Given
8```
9class 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
22class 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
30To create a "nice" mock object which ignores all uninteresting calls,
31or a "strict" mock object, which treats them as failures:
32```
33NiceMock<MockFoo> nice_foo;     // The type is a subclass of MockFoo.
34StrictMock<MockFoo> strict_foo; // The type is a subclass of MockFoo.
35```
36
37## Mocking a Class Template ##
38
39To mock
40```
41template <typename Elem>
42class 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```
52template <typename Elem>
53class 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
63If your mock function doesn't use the default calling convention, you
64can specify it by appending `_WITH_CALLTYPE` to any of the macros
65described in the previous two sections and supplying the calling
66convention 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```
71where `STDMETHODCALLTYPE` is defined by `<objbase.h>` on Windows.
72
73# Using Mocks in Tests #
74
75The 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
83Here is an example:
84```
85using ::testing::Return;                            // #1
86
87TEST(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
105Google Mock has a **built-in default action** for any function that
106returns `void`, `bool`, a numeric value, or a pointer.
107
108To customize the default action for functions with return type `T` globally:
109```
110using ::testing::DefaultValue;
111
112DefaultValue<T>::Set(value);  // Sets the default value to be returned.
113// ... use the mocks ...
114DefaultValue<T>::Clear();     // Resets the default value.
115```
116
117To customize the default action for a particular method, use `ON_CALL()`:
118```
119ON_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
127called? What will it do?):
128```
129EXPECT_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
139If `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
145A 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
149A **matcher** matches a _single_ argument.  You can use it inside
150`ON_CALL()` or `EXPECT_CALL()`, or use it to validate a value
151directly:
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
157Built-in matchers (where `argument` is the function argument) are
158divided 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
179Except `Ref()`, these matchers make a _copy_ of `value` in case it's
180modified or destructed later. If the compiler complains that `value`
181doesn't have a public copy constructor, try wrap it in `ByRef()`,
182e.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
184matcher 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
194The above matchers use ULP-based comparison (the same as used in
195[Google Test](http://code.google.com/p/googletest/)). They
196automatically pick a reasonable error bound based on the absolute
197value of the expected value.  `DoubleEq()` and `FloatEq()` conform to
198the IEEE standard, which requires comparing two NaNs for equality to
199return false. The `NanSensitive*` version instead treats two NaNs as
200equal, 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
210The `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
224syntax defined
225[here](http://code.google.com/p/googletest/wiki/AdvancedGuide#Regular_Expression_Syntax).
226`StrCaseEq()`, `StrCaseNe()`, `StrEq()`, and `StrNe()` work for wide
227strings as well.
228
229## Container Matchers ##
230
231Most STL-style containers support `==`, so you can use
232`Eq(expected_container)` or simply `expected_container` to match a
233container exactly.   If you want to write the elements in-line,
234match 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
250Notes:
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```
259using ::std::tr1::get;
260MATCHER(FooEq, "") {
261  return get<0>(arg).Equals(get<1>(arg));
262}
263...
264EXPECT_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
287Technically, all matchers match a _single_ value. A "multi-argument"
288matcher is just one that matches a _tuple_. The following matchers can
289be 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
299You 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
308You 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
387The return value of the invoked function is used as the return value
388of the action.
389
390When 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
397In `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```
401calls 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
426The `ACTION*` macros cannot be used inside a function or class.
427
428# Cardinalities #
429
430These 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
441By default, the expectations can be matched in _any_ order.  If some
442or all expectations must be matched in a given order, there are two
443ways to specify it.  They can be used either independently or
444together.
445
446## The After Clause ##
447
448```
449using ::testing::Expectation;
450...
451Expectation init_x = EXPECT_CALL(foo, InitX());
452Expectation init_y = EXPECT_CALL(foo, InitY());
453EXPECT_CALL(foo, Bar())
454    .After(init_x, init_y);
455```
456says that `Bar()` can be called only after both `InitX()` and
457`InitY()` have been called.
458
459If you don't know how many pre-requisites an expectation has when you
460write it, you can use an `ExpectationSet` to collect them:
461
462```
463using ::testing::ExpectationSet;
464...
465ExpectationSet all_inits;
466for (int i = 0; i < element_count; i++) {
467  all_inits += EXPECT_CALL(foo, InitElement(i));
468}
469EXPECT_CALL(foo, Bar())
470    .After(all_inits);
471```
472says that `Bar()` can be called only after all elements have been
473initialized (but we don't care about which elements get initialized
474before the others).
475
476Modifying an `ExpectationSet` after using it in an `.After()` doesn't
477affect the meaning of the `.After()`.
478
479## Sequences ##
480
481When you have a long chain of sequential expectations, it's easier to
482specify the order using **sequences**, which don't require you to given
483each expectation in the chain a different name.  <i>All expected<br>
484calls</i> in the same sequence must occur in the order they are
485specified.
486
487```
488using ::testing::Sequence;
489Sequence s1, s2;
490...
491EXPECT_CALL(foo, Reset())
492    .InSequence(s1, s2)
493    .WillOnce(Return(true));
494EXPECT_CALL(foo, GetSize())
495    .InSequence(s1)
496    .WillOnce(Return(1));
497EXPECT_CALL(foo, Describe(A<const char*>()))
498    .InSequence(s2)
499    .WillOnce(Return("dummy"));
500```
501says that `Reset()` must be called before _both_ `GetSize()` _and_
502`Describe()`, and the latter two can occur in any order.
503
504To put many expectations in a sequence conveniently:
505```
506using ::testing::InSequence;
507{
508  InSequence dummy;
509
510  EXPECT_CALL(...)...;
511  EXPECT_CALL(...)...;
512  ...
513  EXPECT_CALL(...)...;
514}
515```
516says that all expected calls in the scope of `dummy` must occur in
517strict order. The name `dummy` is irrelevant.)
518
519# Verifying and Resetting a Mock #
520
521Google Mock will verify the expectations on a mock object when it is destructed, or you can do it earlier:
522```
523using ::testing::Mock;
524...
525// Verifies and removes the expectations on mock_obj;
526// returns true iff successful.
527Mock::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.
532Mock::VerifyAndClear(&mock_obj);
533```
534
535You can also tell Google Mock that a mock object can be leaked and doesn't
536need to be verified:
537```
538Mock::AllowLeak(&mock_obj);
539```
540
541# Mock Classes #
542
543Google Mock defines a convenient mock class template
544```
545class MockFunction<R(A1, ..., An)> {
546 public:
547  MOCK_METHODn(Call, R(A1, ..., An));
548};
549```
550See 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. |