Google Cheat Sheets For La Feria ISD students Thank you to Ben Cogswell. Free DMV Practice Tests. Getting ready for your driving test can be an intense process. In the time leading up to the test a person will be given a lot of information that they are supposed to remember for the test.
Mocking Cheat Sheet References. Testing FAQ Mocking FAQ. Sets the default verbosity level (info, warning, or error) of Google Mock messages.
Defining a Mock Class¶
Mocking a Normal Class {#MockClass}¶
Given
(note that
~Foo()
must be virtual) we can define its mock asTo create a 'nice' mock, which ignores all uninteresting calls, a 'naggy' mock,which warns on all uninteresting calls, or a 'strict' mock, which treats them asfailures:
Note: A mock object is currently naggy by default. We may make it nice bydefault in the future.
Mocking a Class Template {#MockTemplate}¶
Class templates can be mocked just like any class.
To mock
(note that all member functions that are mocked, including
~StackInterface()
must be virtual).Specifying Calling Conventions for Mock Functions¶
If your mock function doesn't use the default calling convention, you canspecify it by adding
Calltype(convention)
to MOCK_METHOD
's 4th parameter.For example,where
STDMETHODCALLTYPE
is defined by <objbase.h>
on Windows.Using Mocks in Tests {#UsingMocks}¶
The typical work flow is:
- Import the gMock names you need to use. All gMock symbols are in the
testing
namespace unless they are macros or otherwise noted. - Create the mock objects.
- Optionally, set the default actions of the mock objects.
- Set your expectations on the mock objects (How will they be called? What will they do?).
- Exercise code that uses the mock objects; if necessary, check the result using googletest assertions.
- When a mock object is destructed, gMock automatically verifies that all expectations on it have been satisfied.
Here's an example:
Setting Default Actions {#OnCall}¶
gMock has a built-in default action for any function that returns
void
,bool
, a numeric value, or a pointer. In C++11, it will additionally returnsthe default-constructed value, if one exists for the given type.To customize the default action for functions with return type
T
:Example usage:
To customize the default action for a particular method of a specific mockobject, use
ON_CALL()
. ON_CALL()
has a similar syntax to EXPECT_CALL()
,but it is used for setting default behaviors (when you do not require that themock method is called). See here for a more detaileddiscussion.Setting Expectations {#ExpectCall}¶
EXPECT_CALL()
sets expectations on a mock method (How will it be called?What will it do?):For each item above,
?
means it can be used at most once, while *
means itcan be used any number of times.In order to pass,
EXPECT_CALL
must be used before the calls are actually made.The
(matchers)
is a comma-separated list of matchers that correspond to eachof the arguments of method
, and sets the expectation only for calls ofmethod
that matches all of the matchers.If
(matchers)
is omitted, the expectation is the same as if the matchers wereset to anything matchers (for example, (_, _, _, _)
for a four-arg method).If
Times()
is omitted, the cardinality is assumed to be:Times(1)
when there is neitherWillOnce()
norWillRepeatedly()
;Times(n)
when there aren
WillOnce()
s but noWillRepeatedly()
, wheren
>= 1; orTimes(AtLeast(n))
when there aren
WillOnce()
s and aWillRepeatedly()
, wheren
>= 0.
A method with no
EXPECT_CALL()
is free to be invoked any number of times,and the default action will be taken each time.Matchers {#MatcherList}¶
A matcher matches a single argument. You can use it inside
ON_CALL()
orEXPECT_CALL()
, or use it to validate a value directly using two macros:Macro | Description |
---|---|
EXPECT_THAT(actual_value, matcher) | Asserts that actual_value matches matcher . |
ASSERT_THAT(actual_value, matcher) | The same as EXPECT_THAT(actual_value, matcher) , except that it generates a fatal failure. |
Note: Although equality matching via
EXPECT_THAT(actual_value,expected_value)
is supported, prefer to make the comparison explicit viaEXPECT_THAT(actual_value, Eq(expected_value))
or EXPECT_EQ(actual_value,expected_value)
.Built-in matchers (where
argument
is the function argument, e.g.actual_value
in the example above, or when used in the context ofEXPECT_CALL(mock_object, method(matchers))
, the arguments of method
) aredivided into several categories:Wildcard¶
Matcher | Description |
---|---|
_ | argument can be any value of the correct type. |
A<type>() or An<type>() | argument can be any value of type type . |
Generic Comparison¶
Matcher | Description |
---|---|
Eq(value) or value | argument value |
Ge(value) | argument >= value |
Gt(value) | argument > value |
Le(value) | argument <= value |
Lt(value) | argument < value |
Ne(value) | argument != value |
IsFalse() | argument evaluates to false in a Boolean context. |
IsTrue() | argument evaluates to true in a Boolean context. |
IsNull() | argument is a NULL pointer (raw or smart). |
NotNull() | argument is a non-null pointer (raw or smart). |
Optional(m) | argument is optional<> that contains a value matching m . (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 .) |
VariantWith<T>(m) | argument is variant<> that holds the alternative of type T with a value matching m . |
Ref(variable) | argument is a reference to variable . |
TypedEq<type>(value) | argument has type type and is equal to value . You may need to use this instead of Eq(value) when the mock function is overloaded. |
Except
Ref()
, these matchers make a copy of value
in case it's modified ordestructed later. If the compiler complains that value
doesn't have a publiccopy constructor, try wrap it in std::ref()
, e.g.Eq(std::ref(non_copyable_value))
. If you do that, make surenon_copyable_value
is not changed afterwards, or the meaning of your matcherwill be changed.IsTrue
and IsFalse
are useful when you need to use a matcher, or for typesthat can be explicitly converted to Boolean, but are not implicitly converted toBoolean. In other cases, you can use the basicEXPECT_TRUE
and EXPECT_FALSE
assertions.Floating-Point Matchers {#FpMatchers}¶
Matcher | Description |
---|---|
DoubleEq(a_double) | argument is a double value approximately equal to a_double , treating two NaNs as unequal. |
FloatEq(a_float) | argument is a float value approximately equal to a_float , treating two NaNs as unequal. |
NanSensitiveDoubleEq(a_double) | argument is a double value approximately equal to a_double , treating two NaNs as equal. |
NanSensitiveFloatEq(a_float) | argument is a float value approximately equal to a_float , treating two NaNs as equal. |
IsNan() | argument is any floating-point type with a NaN value. |
The above matchers use ULP-based comparison (the same as used in googletest).They automatically pick a reasonable error bound based on the absolute value ofthe expected value.
DoubleEq()
and FloatEq()
conform to the IEEE standard,which requires comparing two NaNs for equality to return false. TheNanSensitive*
version instead treats two NaNs as equal, which is often what auser wants.Matcher | Description |
---|---|
DoubleNear(a_double, max_abs_error) | argument is a double value close to a_double (absolute error <= max_abs_error ), treating two NaNs as unequal. |
FloatNear(a_float, max_abs_error) | argument is a float value close to a_float (absolute error <= max_abs_error ), treating two NaNs as unequal. |
NanSensitiveDoubleNear(a_double, max_abs_error) | argument is a double value close to a_double (absolute error <= max_abs_error ), treating two NaNs as equal. |
NanSensitiveFloatNear(a_float, max_abs_error) | argument is a float value close to a_float (absolute error <= max_abs_error ), treating two NaNs as equal. |
String Matchers¶
The
argument
can be either a C string or a C++ string object:Matcher | Description |
---|---|
ContainsRegex(string) | argument matches the given regular expression. |
EndsWith(suffix) | argument ends with string suffix . |
HasSubstr(string) | argument contains string as a sub-string. |
MatchesRegex(string) | argument matches the given regular expression with the match starting at the first character and ending at the last character. |
StartsWith(prefix) | argument starts with string prefix . |
StrCaseEq(string) | argument is equal to string , ignoring case. |
StrCaseNe(string) | argument is not equal to string , ignoring case. |
StrEq(string) | argument is equal to string . |
StrNe(string) | argument is not equal to string . |
ContainsRegex()
and MatchesRegex()
take ownership of the RE
object. Theyuse the regular expression syntax definedhere. All ofthese matchers, except ContainsRegex()
and MatchesRegex()
work for widestrings as well.Container Matchers¶
Most STL-style containers support , so you can use
Eq(expected_container)
or simply expected_container
to match a container exactly. If you want towrite the elements in-line, match them more flexibly, or get more informativemessages, you can use:Matcher | Description |
---|---|
BeginEndDistanceIs(m) | argument is a container whose begin() and end() iterators are separated by a number of increments matching m . E.g. BeginEndDistanceIs(2) or BeginEndDistanceIs(Lt(2)) . For containers that define a size() method, SizeIs(m) may be more efficient. |
ContainerEq(container) | The same as Eq(container) except that the failure message also includes which elements are in one container but not the other. |
Contains(e) | argument contains an element that matches e , which can be either a value or a matcher. |
Each(e) | argument is a container where every element matches e , which can be either a value or a matcher. |
ElementsAre(e0, e1, ..., en) | argument has n + 1 elements, where the i-th element matches ei , which can be a value or a matcher. |
ElementsAreArray({e0, e1, ..., en}) , ElementsAreArray(a_container) , ElementsAreArray(begin, end) , ElementsAreArray(array) , or ElementsAreArray(array, count) | The same as ElementsAre() except that the expected element values/matchers come from an initializer list, STL-style container, iterator range, or C-style array. |
IsEmpty() | argument is an empty container (container.empty() ). |
IsSubsetOf({e0, e1, ..., en}) , IsSubsetOf(a_container) , IsSubsetOf(begin, end) , IsSubsetOf(array) , or IsSubsetOf(array, count) | argument matches UnorderedElementsAre(x0, x1, ..., xk) for some subset {x0, x1, ..., xk} of the expected matchers. |
IsSupersetOf({e0, e1, ..., en}) , IsSupersetOf(a_container) , IsSupersetOf(begin, end) , IsSupersetOf(array) , or IsSupersetOf(array, count) | Some subset of argument matches UnorderedElementsAre( expected matchers) . |
Pointwise(m, container) , Pointwise(m, {e0, e1, ..., en}) | argument contains the same number of elements as in container , and for all i, (the i-th element in argument , the i-th element in container ) match m , which is a matcher on 2-tuples. E.g. Pointwise(Le(), upper_bounds) verifies that each element in argument doesn't exceed the corresponding element in upper_bounds . See more detail below. |
SizeIs(m) | argument is a container whose size matches m . E.g. SizeIs(2) or SizeIs(Lt(2)) . |
UnorderedElementsAre(e0, e1, ..., en) | argument has n + 1 elements, and under some permutation of the elements, each element matches an ei (for a different i ), which can be a value or a matcher. |
UnorderedElementsAreArray({e0, e1, ..., en}) , UnorderedElementsAreArray(a_container) , UnorderedElementsAreArray(begin, end) , UnorderedElementsAreArray(array) , or UnorderedElementsAreArray(array, count) | The same as UnorderedElementsAre() except that the expected element values/matchers come from an initializer list, STL-style container, iterator range, or C-style array. |
UnorderedPointwise(m, container) , UnorderedPointwise(m, {e0, e1, ..., en}) | Like Pointwise(m, container) , but ignores the order of elements. |
WhenSorted(m) | When argument is sorted using the < operator, it matches container matcher m . E.g. WhenSorted(ElementsAre(1, 2, 3)) verifies that argument contains elements 1, 2, and 3, ignoring order. |
WhenSortedBy(comparator, m) | The same as WhenSorted(m) , except that the given comparator instead of < is used to sort argument . E.g. WhenSortedBy(std::greater(), ElementsAre(3, 2, 1)) . |
Notes:
- These matchers can also match:
- a native array passed by reference (e.g. in
Foo(const int (&a)[5])
), and - an array passed as a pointer and a count (e.g. in
Bar(const T* buffer, int len)
-- see Multi-argument Matchers).
- a native array passed by reference (e.g. in
- The array being matched may be multi-dimensional (i.e. its elements can be arrays).
m
inPointwise(m, ...)
should be a matcher for::std::tuple<T, U>
whereT
andU
are the element type of the actual container and the expected container, respectively. For example, to compare twoFoo
containers whereFoo
doesn't supportoperator
, one might write:cppusing ::std::get;MATCHER(FooEq, ') { return std::get<0>(arg).Equals(std::get<1>(arg));}...EXPECT_THAT(actual_foos, Pointwise(FooEq(), expected_foos));
Member Matchers¶
Matcher | Description |
---|---|
Field(&class::field, m) | argument.field (or argument->field when argument is a plain pointer) matches matcher m , where argument is an object of type class. |
Key(e) | argument.first matches e , which can be either a value or a matcher. E.g. Contains(Key(Le(5))) can verify that a map contains a key <= 5 . |
Pair(m1, m2) | argument is an std::pair whose first field matches m1 and second field matches m2 . |
Property(&class::property, m) | argument.property() (or argument->property() when argument is a plain pointer) matches matcher m , where argument is an object of type class. |
Matching the Result of a Function, Functor, or Callback¶
Matcher | Description |
---|---|
ResultOf(f, m) | f(argument) matches matcher m , where f is a function or functor. |
Pointer Matchers¶
Matcher | Description |
---|---|
Pointee(m) | argument (either a smart pointer or a raw pointer) points to a value that matches matcher m . |
WhenDynamicCastTo<T>(m) | when argument is passed through dynamic_cast<T>() , it matches matcher m . |
Multi-argument Matchers {#MultiArgMatchers}¶
Technically, all matchers match a single value. A 'multi-argument' matcher isjust one that matches a tuple. The following matchers can be used to match atuple
(x, y)
:Matcher | Description |
---|---|
Eq() | x y |
Ge() | x >= y |
Gt() | x > y |
Le() | x <= y |
Lt() | x < y |
Ne() | x != y |
You can use the following selectors to pick a subset of the arguments (orreorder them) to participate in the matching:
Matcher | Description |
---|---|
AllArgs(m) | Equivalent to m . Useful as syntactic sugar in .With(AllArgs(m)) . |
Args<N1, N2, ..., Nk>(m) | The tuple of the k selected (using 0-based indices) arguments matches m , e.g. Args<1, 2>(Eq()) . |
Composite Matchers¶
You can make a matcher from one or more other matchers:
Gmock Cheat Sheet
Matcher | Description |
---|---|
AllOf(m1, m2, ..., mn) | argument matches all of the matchers m1 to mn . |
AllOfArray({m0, m1, ..., mn}) , AllOfArray(a_container) , AllOfArray(begin, end) , AllOfArray(array) , or AllOfArray(array, count) | The same as AllOf() except that the matchers come from an initializer list, STL-style container, iterator range, or C-style array. |
AnyOf(m1, m2, ..., mn) | argument matches at least one of the matchers m1 to mn . |
AnyOfArray({m0, m1, ..., mn}) , AnyOfArray(a_container) , AnyOfArray(begin, end) , AnyOfArray(array) , or AnyOfArray(array, count) | The same as AnyOf() except that the matchers come from an initializer list, STL-style container, iterator range, or C-style array. |
Not(m) | argument doesn't match matcher m . |
Adapters for Matchers¶
Matcher | Description |
---|---|
MatcherCast<T>(m) | casts matcher m to type Matcher<T> . |
SafeMatcherCast<T>(m) | safely casts matcher m to type Matcher<T> . |
Truly(predicate) | predicate(argument) returns something considered by C++ to be true, where predicate is a function or functor. |
AddressSatisfies(callback)
and Truly(callback)
take ownership of callback
,which must be a permanent callback.Using Matchers as Predicates {#MatchersAsPredicatesCheat}¶
Google Mock Matcher
Matcher | Description |
---|---|
Matches(m)(value) | evaluates to true if value matches m . You can use Matches(m) alone as a unary functor. |
ExplainMatchResult(m, value, result_listener) | evaluates to true if value matches m , explaining the result to result_listener . |
Value(value, m) | evaluates to true if value matches m . |
Defining Matchers¶
Matcher | Description |
---|---|
MATCHER(IsEven, ') { return (arg % 2) 0; } | Defines a matcher IsEven() to match an even number. |
MATCHER_P(IsDivisibleBy, n, ') { *result_listener << 'where the remainder is ' << (arg % n); return (arg % n) 0; } | Defines a matcher IsDivisibleBy(n) to match a number divisible by n . |
MATCHER_P2(IsBetween, a, b, std::string(negation ? 'isn't' : 'is') + ' between ' + PrintToString(a) + ' and ' + PrintToString(b)) { return a <= arg && arg <= b; } | Defines a matcher IsBetween(a, b) to match a value in the range [a , b ]. |
Notes:
- The
MATCHER*
macros cannot be used inside a function or class. - 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).
- You can use
PrintToString(x)
to convert a valuex
of any type to a string.
Actions {#ActionList}¶
Actions specify what a mock function should do when invoked.
Returning a Value¶
Return() | Return from a void mock function. |
Return(value) | Return value . If the type of value is different to the mock function's return type, value is converted to the latter type at the time the expectation is set, not when the action is executed. |
ReturnArg<N>() | Return the N -th (0-based) argument. |
ReturnNew<T>(a1, ..., ak) | Return new T(a1, ..., ak) ; a different object is created each time. |
ReturnNull() | Return a null pointer. |
ReturnPointee(ptr) | Return the value pointed to by ptr . |
ReturnRef(variable) | Return a reference to variable . |
ReturnRefOfCopy(value) | Return a reference to a copy of value ; the copy lives as long as the action. |
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. |
Side Effects¶
Assign(&variable, value) | Assign value to variable. |
DeleteArg<N>() | Delete the N -th (0-based) argument, which must be a pointer. |
SaveArg<N>(pointer) | Save the N -th (0-based) argument to *pointer . |
SaveArgPointee<N>(pointer) | Save the value pointed to by the N -th (0-based) argument to *pointer . |
SetArgReferee<N>(value) | Assign value to the variable referenced by the N -th (0-based) argument. |
SetArgPointee<N>(value) | Assign value to the variable pointed by the N -th (0-based) argument. |
SetArgumentPointee<N>(value) | Same as SetArgPointee<N>(value) . Deprecated. Will be removed in v1.7.0. |
SetArrayArgument<N>(first, last) | Copies the elements in source range [first , last ) to the array pointed to by the N -th (0-based) argument, which can be either a pointer or an iterator. The action does not take ownership of the elements in the source range. |
SetErrnoAndReturn(error, value) | Set errno to error and return value . |
Throw(exception) | Throws the given exception, which can be any copyable value. Available since v1.1.0. |
Using a Function, Functor, or Lambda as an Action¶
In the following, by 'callable' we mean a free function,
std::function
,functor, or lambda.f | Invoke f with the arguments passed to the mock function, where f is a callable. |
Invoke(f) | Invoke f with the arguments passed to the mock function, where f can be a global/static function or a functor. |
Invoke(object_pointer, &class::method) | Invoke the method on the object with the arguments passed to the mock function. |
InvokeWithoutArgs(f) | Invoke f , which can be a global/static function or a functor. f must take no arguments. |
InvokeWithoutArgs(object_pointer, &class::method) | Invoke the method on the object, which takes no arguments. |
InvokeArgument<N>(arg1, arg2, ..., argk) | Invoke the mock function's N -th (0-based) argument, which must be a function or a functor, with the k arguments. |
The return value of the invoked function is used as the return value of theaction.
When defining a callable to be used with
Invoke*()
, you can declare any unusedparameters as Unused
:Invoke(callback)
and InvokeWithoutArgs(callback)
take ownership ofcallback
, which must be permanent. The type of callback
must be a basecallback type instead of a derived one, e.g.In
InvokeArgument<N>(...)
, if an argument needs to be passed by reference,wrap it inside std::ref()
. For example,calls the mock function's #2 argument, passing to it
5
and string('Hi')
byvalue, and foo
by reference.Default Action¶
Matcher | Description |
---|---|
DoDefault() | Do the default action (specified by ON_CALL() or the built-in one). |
Note: due to technical reasons,
DoDefault()
cannot be used inside acomposite action - trying to do so will result in a run-time error.Composite Actions¶
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 and will receive a readonly view of the arguments. |
IgnoreResult(a) | Perform action a and ignore its result. a must not return void. |
WithArg<N>(a) | Pass the N -th (0-based) argument of the mock function to action a and perform it. |
WithArgs<N1, N2, ..., Nk>(a) | Pass the selected (0-based) arguments of the mock function to action a and perform it. |
WithoutArgs(a) | Perform action a without any arguments. |
Defining Actions¶
ACTION(Sum) { return arg0 + arg1; } | Defines an action Sum() to return the sum of the mock function's argument #0 and #1. |
ACTION_P(Plus, n) { return arg0 + n; } | Defines an action Plus(n) to return the sum of the mock function's argument #0 and n . |
ACTION_Pk(Foo, p1, ..., pk) { statements; } | Defines a parameterized action Foo(p1, ..., pk) to execute the given statements . |
The
ACTION*
macros cannot be used inside a function or class.Cardinalities {#CardinalityList}¶
These are used in
Times()
to specify how many times a mock function will becalled:AnyNumber() | The function can be called any number of times. |
AtLeast(n) | The call is expected at least n times. |
AtMost(n) | The call is expected at most n times. |
Between(m, n) | The call is expected between m and n (inclusive) times. |
Exactly(n) or n | The call is expected exactly n times. In particular, the call should never happen when n is 0. |
Expectation Order¶
By default, the expectations can be matched in any order. If some or allexpectations must be matched in a given order, there are two ways to specify it.They can be used either independently or together.
The After Clause {#AfterClause}¶
says that
Bar()
can be called only after both InitX()
and InitY()
havebeen called.Google Test Matcher
If you don't know how many pre-requisites an expectation has when you write it,you can use an
ExpectationSet
to collect them:says that
Bar()
can be called only after all elements have been initialized(but we don't care about which elements get initialized before the others).Modifying an
ExpectationSet
after using it in an .After()
doesn't affect themeaning of the .After()
.Sequences {#UsingSequences}¶
When you have a long chain of sequential expectations, it's easier to specifythe order using sequences, which don't require you to given each expectationin the chain a different name. All expected calls in the same sequence mustoccur in the order they are specified.
says that
Reset()
must be called before bothGetSize()
andDescribe()
,and the latter two can occur in any order.To put many expectations in a sequence conveniently:
says that all expected calls in the scope of
seq
must occur in strict order.The name seq
is irrelevant.Verifying and Resetting a Mock¶
gMock will verify the expectations on a mock object when it is destructed, oryou can do it earlier:
![Google mock tutorial Google mock tutorial](/uploads/1/1/7/7/117716975/623847532.png)
You can also tell gMock that a mock object can be leaked and doesn't need to beverified:
Mock Classes¶
gMock defines a convenient mock class template
See this recipe for one application of it.
Flags¶
Google Mock Tutorial
Flag | Description |
---|---|
--gmock_catch_leaked_mocks=0 | Don't report leaked mock objects as failures. |
--gmock_verbose=LEVEL | Sets the default verbosity level (info , warning , or error ) of Google Mock messages. |