c++ - How to set a value to void * argument of a mock method in google mock testing?

C++ - How to set a value to void * argument of a mock method in google mock testing?

In Google Mock, if you need to set a value to a void* argument in a mock method, you can use the SetArgPointee function provided by the Google Mock framework. This allows you to specify a value that should be used when the mock method is called with a void* argument.

Here's a step-by-step guide to using SetArgPointee for a void* argument in Google Mock:

1. Include Necessary Headers

Make sure to include the headers for Google Mock and Google Test in your code:

#include <gtest/gtest.h> #include <gmock/gmock.h>

2. Define the Mock Class

Define a mock class using Google Mock. Suppose you have a function with a void* argument, and you want to set a value for that argument in your tests:

class MyClass { public: virtual void MyFunction(void* data) = 0; }; class MockMyClass : public MyClass { public: MOCK_METHOD(void, MyFunction, (void* data), (override)); };

3. Set Up the Test

In your test, use SetArgPointee to set the value of the void* argument. You will need to cast the void* to the appropriate type. Here's an example:

TEST(MyClassTest, MyFunctionSetsValue) { MockMyClass mock; // Define a value to be set int expectedValue = 42; // Set up the mock method to set the expected value to the void* argument EXPECT_CALL(mock, MyFunction(::testing::_)) .WillOnce(::testing::SetArgPointee<0>(&expectedValue)); // Call the function under test void* data = nullptr; mock.MyFunction(data); // Assert that the value was set correctly EXPECT_EQ(*static_cast<int*>(data), 42); }

Explanation

  1. Mock Definition: The MockMyClass class mocks MyFunction which takes a void* parameter.
  2. SetArgPointee Usage: The SetArgPointee<0>(&expectedValue) call sets the value of the void* argument. Here, 0 is the index of the argument in the method signature.
  3. Casting: You need to cast the void* back to its original type when asserting its value. In this case, we cast it to int*.

Additional Notes

  • Indexing: SetArgPointee<0>(...) uses zero-based indexing to specify which argument to modify. If the method had more arguments, you would adjust the index accordingly.
  • Type Safety: Ensure you cast the void* to the correct type when you use it. Incorrect casting can lead to undefined behavior.

Complete Example

Here is a complete example of a Google Mock test with void*:

#include <gtest/gtest.h> #include <gmock/gmock.h> class MyClass { public: virtual void MyFunction(void* data) = 0; }; class MockMyClass : public MyClass { public: MOCK_METHOD(void, MyFunction, (void* data), (override)); }; TEST(MyClassTest, MyFunctionSetsValue) { MockMyClass mock; // Define a value to be set int expectedValue = 42; // Set up the mock method to set the expected value to the void* argument EXPECT_CALL(mock, MyFunction(::testing::_)) .WillOnce(::testing::SetArgPointee<0>(&expectedValue)); // Call the function under test void* data = nullptr; mock.MyFunction(data); // Assert that the value was set correctly EXPECT_EQ(*static_cast<int*>(data), 42); }

By following these steps, you can effectively handle void* arguments in Google Mock and set their values as needed for your unit tests.

Examples

  1. c++ google mock set value for void* argument

    • Description: This query demonstrates how to set a value for a void* argument in a mock method and verify it.
    • Code:
      #include <gtest/gtest.h> #include <gmock/gmock.h> class MyClass { public: virtual void MyMethod(void* ptr) = 0; }; class MockMyClass : public MyClass { public: MOCK_METHOD(void, MyMethod, (void*), (override)); }; TEST(MockTest, SetVoidPointerValue) { MockMyClass mock; int testValue = 42; EXPECT_CALL(mock, MyMethod(testing::Pointee(testValue))) .Times(1); int value = 42; mock.MyMethod(&value); }
      Explanation: This code sets up a mock method MyMethod that takes a void* argument. The test uses testing::Pointee to match the expected value pointed to by the void* argument.

  2. c++ google mock set void* to specific type

    • Description: This query shows how to cast a void* argument to a specific type in Google Mock expectations.
    • Code:
      #include <gtest/gtest.h> #include <gmock/gmock.h> class MyClass { public: virtual void MyMethod(void* ptr) = 0; }; class MockMyClass : public MyClass { public: MOCK_METHOD(void, MyMethod, (void*), (override)); }; TEST(MockTest, SetVoidPointerToType) { MockMyClass mock; int expectedValue = 100; EXPECT_CALL(mock, MyMethod(testing::Truly([&](void* ptr) { return *static_cast<int*>(ptr) == expectedValue; }))) .Times(1); int value = 100; mock.MyMethod(&value); }
      Explanation: This test uses a lambda function with testing::Truly to cast void* to int* and check the value.

  3. c++ google mock match void* argument using pointer comparison

    • Description: This query shows how to use pointer comparison for a void* argument in Google Mock.
    • Code:
      #include <gtest/gtest.h> #include <gmock/gmock.h> class MyClass { public: virtual void MyMethod(void* ptr) = 0; }; class MockMyClass : public MyClass { public: MOCK_METHOD(void, MyMethod, (void*), (override)); }; TEST(MockTest, MatchVoidPointerByAddress) { MockMyClass mock; int value1 = 123; int value2 = 456; EXPECT_CALL(mock, MyMethod(testing::Eq(&value1))) .Times(1); mock.MyMethod(&value1); }
      Explanation: This code uses testing::Eq to match the address of a void* argument.

  4. c++ google mock verify void* argument value

    • Description: This query demonstrates how to verify the value pointed to by a void* argument in a mock method.
    • Code:
      #include <gtest/gtest.h> #include <gmock/gmock.h> class MyClass { public: virtual void MyMethod(void* ptr) = 0; }; class MockMyClass : public MyClass { public: MOCK_METHOD(void, MyMethod, (void*), (override)); }; TEST(MockTest, VerifyVoidPointerValue) { MockMyClass mock; int expectedValue = 200; EXPECT_CALL(mock, MyMethod(testing::Truly([&](void* ptr) { int* intPtr = static_cast<int*>(ptr); return *intPtr == expectedValue; }))) .Times(1); int value = 200; mock.MyMethod(&value); }
      Explanation: This test uses testing::Truly with a lambda to verify that the void* argument points to an integer with the expected value.

  5. c++ google mock set up void* argument with custom matcher

    • Description: This query demonstrates setting up a custom matcher for a void* argument in Google Mock.
    • Code:
      #include <gtest/gtest.h> #include <gmock/gmock.h> class MyClass { public: virtual void MyMethod(void* ptr) = 0; }; class MockMyClass : public MyClass { public: MOCK_METHOD(void, MyMethod, (void*), (override)); }; bool IsPointerToInt(void* ptr) { return dynamic_cast<int*>(ptr) != nullptr; } TEST(MockTest, CustomMatcherForVoidPointer) { MockMyClass mock; EXPECT_CALL(mock, MyMethod(testing::Truly(IsPointerToInt))) .Times(1); int value = 300; mock.MyMethod(&value); }
      Explanation: This test uses a custom matcher IsPointerToInt to check if the void* argument points to an int.

  6. c++ google mock test void* argument with value using gmock

    • Description: This query shows how to test a void* argument with a specific value using Google Mock.
    • Code:
      #include <gtest/gtest.h> #include <gmock/gmock.h> class MyClass { public: virtual void MyMethod(void* ptr) = 0; }; class MockMyClass : public MyClass { public: MOCK_METHOD(void, MyMethod, (void*), (override)); }; TEST(MockTest, TestVoidPointerWithValue) { MockMyClass mock; int expectedValue = 400; EXPECT_CALL(mock, MyMethod(testing::Pointee(expectedValue))) .Times(1); int value = 400; mock.MyMethod(&value); }
      Explanation: This code uses testing::Pointee to test if the void* argument points to an integer with the expected value.

  7. c++ google mock check void* argument type

    • Description: This query demonstrates how to check the type of a void* argument in Google Mock.
    • Code:
      #include <gtest/gtest.h> #include <gmock/gmock.h> class MyClass { public: virtual void MyMethod(void* ptr) = 0; }; class MockMyClass : public MyClass { public: MOCK_METHOD(void, MyMethod, (void*), (override)); }; TEST(MockTest, CheckVoidPointerType) { MockMyClass mock; EXPECT_CALL(mock, MyMethod(testing::Truly([](void* ptr) { return dynamic_cast<int*>(ptr) != nullptr; }))) .Times(1); int value = 500; mock.MyMethod(&value); }
      Explanation: This test uses testing::Truly with a lambda to check if the void* argument can be cast to an int*.

  8. c++ google mock set void* argument and verify

    • Description: This query demonstrates setting a void* argument and verifying its value in a Google Mock test.
    • Code:
      #include <gtest/gtest.h> #include <gmock/gmock.h> class MyClass { public: virtual void MyMethod(void* ptr) = 0; }; class MockMyClass : public MyClass { public: MOCK_METHOD(void, MyMethod, (void*), (override)); }; TEST(MockTest, SetAndVerifyVoidPointer) { MockMyClass mock; int testValue = 600; EXPECT_CALL(mock, MyMethod(testing::Pointee(testValue))) .Times(1); int value = 600; mock.MyMethod(&value); }
      Explanation: This code sets up a mock expectation to verify that the void* argument points to an integer with the expected value.

  9. c++ google mock set void* argument in mock expectation

    • Description: This query shows how to set a void* argument in a mock expectation.
    • Code:
      #include <gtest/gtest.h> #include <gmock/gmock.h> class MyClass { public: virtual void MyMethod(void* ptr) = 0; }; class MockMyClass : public MyClass { public: MOCK_METHOD(void, MyMethod, (void*), (override)); }; TEST(MockTest, SetVoidPointerInExpectation) { MockMyClass mock; int expectedValue = 700; EXPECT_CALL(mock, MyMethod(testing::Truly([&](void* ptr) { return *static_cast<int*>(ptr) == expectedValue; }))) .Times(1); int value = 700; mock.MyMethod(&value); }
      Explanation: This test uses testing::Truly to verify that the void* argument points to an integer with the expected value.

  10. c++ google mock set void* argument with parameterized test

    • Description: This query demonstrates setting a void* argument in a parameterized Google Mock test.
    • Code:
      #include <gtest/gtest.h> #include <gmock/gmock.h> class MyClass { public: virtual void MyMethod(void* ptr) = 0; }; class MockMyClass : public MyClass { public: MOCK_METHOD(void, MyMethod, (void*), (override)); }; class MyTest : public ::testing::TestWithParam<int> { protected: MockMyClass mock; }; TEST_P(MyTest, ParameterizedVoidPointerTest) { int param = GetParam(); EXPECT_CALL(mock, MyMethod(testing::Truly([param](void* ptr) { return *static_cast<int*>(ptr) == param; }))) .Times(1); mock.MyMethod(&param); } INSTANTIATE_TEST_SUITE_P(MyTests, MyTest, ::testing::Values(800, 900, 1000));
      Explanation: This parameterized test uses INSTANTIATE_TEST_SUITE_P to run the test with different values for the void* argument and verify them using testing::Truly.

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