我正在为新组件编写单元测试，其中一个接口方法返回一个具有多个用户定义转换的对象。在模拟这样的方法时，似乎编译器抱怨模棱两可：
gdpr1@BEL081089 ~/Code/sandbox/mocking
$ make && ./tests.exe
Scanning dependencies of target tests
[ 25%] Building CXX object CMakeFiles/tests.dir/Foo.cpp.o
[ 50%] Building CXX object CMakeFiles/tests.dir/FooTest.cpp.o
In file included from /cygdrive/c/GPDR1/Code/googletest/googletest/include/gtest/gtest.h:58:0,
from /cygdrive/c/GPDR1/Code/googletest/googlemock/include/gmock/internal/gmock-internal-utils.h:46,
from /cygdrive/c/GPDR1/Code/googletest/googlemock/include/gmock/gmock-actions.h:46,
from /cygdrive/c/GPDR1/Code/googletest/googlemock/include/gmock/gmock.h:58,
from /home/gdpr1/Code/sandbox/mocking/FooTest.cpp:1:
/cygdrive/c/GPDR1/Code/googletest/googletest/include/gtest/internal/gtest-internal.h: In instantiation of ‘const bool testing::internal::ImplicitlyConvertible<const Trouble&, long long int>::value’:
/cygdrive/c/GPDR1/Code/googletest/googletest/include/gtest/gtest-printers.h:236:38: required from ‘std::basic_ostream<_CharT, _Traits>& testing::internal2::operator<<(std::basic_ostream<_CharT, _Traits>&, const T&) [with Char = char; CharTraits = std::char_traits<char>; T = Trouble]’
/cygdrive/c/GPDR1/Code/googletest/googletest/include/gtest/gtest-printers.h:285:7: required from ‘void testing_internal::DefaultPrintNonContainerTo(const T&, std::ostream*) [with T = Trouble; std::ostream = std::basic_ostream<char>]’
/cygdrive/c/GPDR1/Code/googletest/googletest/include/gtest/gtest-printers.h:476:49: required from ‘void testing::internal::DefaultPrintTo(testing::internal::WrapPrinterType<(testing::internal::DefaultPrinterType)3u>, const T&, std::ostream*) [with T = Trouble; std::ostream = std::basic_ostream<char>]’
/cygdrive/c/GPDR1/Code/googletest/googletest/include/gtest/gtest-printers.h:511:17: required from ‘void testing::internal::PrintTo(const T&, std::ostream*) [with T = Trouble; std::ostream = std::basic_ostream<char>]’
/cygdrive/c/GPDR1/Code/googletest/googletest/include/gtest/gtest-printers.h:762:12: required from ‘static void testing::internal::UniversalPrinter<T>::Print(const T&, std::ostream*) [with T = Trouble; std::ostream = std::basic_ostream<char>]’
/cygdrive/c/GPDR1/Code/googletest/googlemock/include/gmock/gmock-spec-builders.h:1385:31: required from ‘void testing::internal::ActionResultHolder<T>::PrintAsActionResult(std::ostream*) const [with T = Trouble; std::ostream = std::basic_ostream<char>]’
/home/gdpr1/Code/sandbox/mocking/FooTest.cpp:21:1: required from here
/cygdrive/c/GPDR1/Code/googletest/googletest/include/gtest/internal/gtest-internal.h:850:20: error: conversion from ‘const Trouble’ to ‘long long int’ is ambiguous
sizeof(Helper(ImplicitlyConvertible::MakeFrom())) == 1;
~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /home/gdpr1/Code/sandbox/mocking/Bar.h:7:0,
from /home/gdpr1/Code/sandbox/mocking/FooTest.cpp:3:
/home/gdpr1/Code/sandbox/mocking/Foo.h:17:5: note: candidate: Trouble::operator int() const
operator int() const { return value; }
^~~~~~~~
/home/gdpr1/Code/sandbox/mocking/Foo.h:16:5: note: candidate: Trouble::operator short int() const
operator short() const { return value; }
^~~~~~~~
In file included from /cygdrive/c/GPDR1/Code/googletest/googletest/include/gtest/gtest.h:58:0,
from /cygdrive/c/GPDR1/Code/googletest/googlemock/include/gmock/internal/gmock-internal-utils.h:46,
from /cygdrive/c/GPDR1/Code/googletest/googlemock/include/gmock/gmock-actions.h:46,
from /cygdrive/c/GPDR1/Code/googletest/googlemock/include/gmock/gmock.h:58,
from /home/gdpr1/Code/sandbox/mocking/FooTest.cpp:1:
/cygdrive/c/GPDR1/Code/googletest/googletest/include/gtest/internal/gtest-internal.h:833:15: note: initializing argument 1 of ‘static char testing::internal::ImplicitlyConvertible<From, To>::Helper(To) [with From = const Trouble&; To = long long int]’
static char Helper(To);
^~~~~~
make[2]: *** [CMakeFiles/tests.dir/build.make:87: CMakeFiles/tests.dir/FooTest.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:68: CMakeFiles/tests.dir/all] Error 2
make: *** [Makefile:95: all] Error 2
这是一个显示问题的小文件：
的main.cpp
#include "gmock/gmock.h"
#include "gtest/gtest.h"
class Special
{
private:
char value;
public:
Special(char v) : value(v) {}
operator short() const { return value; }
operator int() const { return value; }
};
class Foo
{
public:
virtual ~Foo() {};
virtual Foo& foo() = 0;
virtual Special getVariant() = 0;
};
class MockFoo : public Foo
{
public:
MOCK_METHOD0(foo, Foo&());
MOCK_METHOD0(getVariant, Special());
};
TEST(FooTest, callFoo)
{
MockFoo myFoo;
::testing::DefaultValue<Foo&>::Set(myFoo);
EXPECT_CALL(myFoo, foo()).Times(1);
myFoo.foo();
}
int main(int argc, char **argv) {
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}
我在Windows 7机器上使用Cygwin（CYGWIN_NT-6.1-WOW），gcc版本是6.4.0，我使用的是C ++ 98。我的cmake文件是：
的CMakeLists.txt
cmake_minimum_required (VERSION 3.6)
project (httpproperpty)
set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/build/lib)
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/build/lib)
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/build/bin)
include_directories("${PROJECT_BINARY_DIR}")
include_directories("/cygdrive/c/GPDR1/Code/googletest/googletest/include")
include_directories("/cygdrive/c/GPDR1/Code/googletest/googlemock/include")
LINK_DIRECTORIES("/cygdrive/c/GPDR1/Code/googletest/googlemock/")
LINK_DIRECTORIES("/cygdrive/c/GPDR1/Code/googletest/googlemock/gtest/")
# file(GLOB Source_files "*.cpp")
set(CMAKE_CXX_STANDARD 98)
add_executable(tests "main.cpp")
target_link_libraries (tests gtest gmock)
enable_testing()
add_test(NAME mytests
COMMAND tests)
我已经搜索过，但找不到任何解决方案。关于如何解决这个问题的任何想法？我可以从用户定义的转换方法中删除const，但我怀疑这是一个正确的解决方案。无论如何，在我的实际代码中，我不能轻易地改变方法。
到目前为止，唯一的解决方案是使用存根而不是模拟返回此对象的方法（getVariant），但这在长队中并不是一个很好的解决方案。
答案 0 :(得分：0)
上例中的解决方案是添加用户定义的转化以转换为long long int：
operator long long int() const { return value; }
到Special班级
class Special
{
private:
char value;
public:
Special(char v) : value(v) {}
operator short() const { return value; }
operator int() const { return value; }
operator long long int() const { return value; }
};
这解决了歧义。存在歧义是因为Helper类想要将其转换为long long int，编译器可以选择将其转换为short或int，两者都可以转换到long long int。