Catch fails on simple example - c++

Question

I am trying to integrate Catch unit testing to my project but it fails for the currently available
Catch v1.10.0
Generated: 2017-08-26 15:16:46.676990
Example:
test.cpp
#include "catch.hpp"
#define CATCH_CONFIG_MAIN
TEST_CASE("CATCH TEST"){
REQUIRE(1 == 1);
}
g++ test.cpp -o test.exe -std=c++11
Error:
Undefined symbols for architecture x86_64:
"Catch::ResultBuilder::endExpression(Catch::DecomposedExpression const&)", referenced from:
Catch::BinaryExpression<int const&, (Catch::Internal::Operator)0, int const&>::endExpression() const in test-b77427.o
"Catch::ResultBuilder::setResultType(bool)", referenced from:
Catch::BinaryExpression<int const&, (Catch::Internal::Operator)0, int const&>::endExpression() const in test-b77427.o
"Catch::ResultBuilder::useActiveException(Catch::ResultDisposition::Flags)", referenced from:
____C_A_T_C_H____T_E_S_T____0() in test-b77427.o
"Catch::ResultBuilder::react()", referenced from:
____C_A_T_C_H____T_E_S_T____0() in test-b77427.o
"Catch::ResultBuilder::ResultBuilder(char const*, Catch::SourceLineInfo const&, char const*, Catch::ResultDisposition::Flags, char const*)", referenced from:
____C_A_T_C_H____T_E_S_T____0() in test-b77427.o
"Catch::ResultBuilder::~ResultBuilder()", referenced from:
____C_A_T_C_H____T_E_S_T____0() in test-b77427.o
"Catch::SourceLineInfo::SourceLineInfo(char const*, unsigned long)", referenced from:
____C_A_T_C_H____T_E_S_T____0() in test-b77427.o
___cxx_global_var_init in test-b77427.o
"Catch::isDebuggerActive()", referenced from:
____C_A_T_C_H____T_E_S_T____0() in test-b77427.o
"Catch::AutoReg::AutoReg(void (*)(), Catch::SourceLineInfo const&, Catch::NameAndDesc const&)", referenced from:
___cxx_global_var_init in test-b77427.o
"Catch::AutoReg::~AutoReg()", referenced from:
___cxx_global_var_init in test-b77427.o
"Catch::toString(int)", referenced from:
Catch::ExpressionLhs<int const&>::reconstructExpression(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >&) const in test-b77427.o
Catch::BinaryExpression<int const&, (Catch::Internal::Operator)0, int const&>::reconstructExpression(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >&) const in test-b77427.o
"Catch::ResultBuilder::shouldDebugBreak() const", referenced from:
____C_A_T_C_H____T_E_S_T____0() in test-b77427.o
"_main", referenced from:
implicit entry/start for main executable
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit
g++ --version
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/usr/include/c++/4.2.1
Apple LLVM version 8.1.0 (clang-802.0.42)
Target: x86_64-apple-darwin16.7.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

Answer 1

As it stands your program does not have a main function. If you compile it, the linker will complain about the absence of a main function. Since you are writing unit tests using the catch framework, you want that framework to generate a main function for you.
The catch framework looks whether CATCH_CONFIG_MAIN is defined and if yes, it generates a main function for you which runs all the tests you define. Because compilation is a linear process, the macro CATCH_CONFIG_MAIN has to be defined before including catch.hpp. Otherwise, the library will never “see” this macro.
#define CATCH_CONFIG_MAIN
#include "catch.hpp"
TEST_CASE("CATCH TEST"){
REQUIRE(1 == 1);
}
Live example