How do I set up Google Test with a GNU Make project?

Question

Since there's basically no documentation on the Google Test webpage—how do I do that? What I have done until now:

• I downloaded googletest 1.6 from the project page and did a ./configure && make inside it
• I added -Igtest/include -Lgtest/lib to my compiler/linker flags

• I wrote a small sample test:

  #include "gtest/gtest.h"
  
  int main(int argc, char **args)
  {
    return 0;
  }
  
  TEST(someTest,testOne)
  {
    ASSERT_EQ(5,5);
  }
  

  This compiles fine, but the linker seems not to be amused at all. I get a huge pile of error messages in the style of

  test/main.o: In function someTest_testOne_Test::TestBody()': main.cpp:(.text+0x96): undefined reference totesting::internal::AssertHelper::AssertHelper(testing::TestPartResult::Type, char const*, int, char const*)'

Now what did I forget to do?

Answer 1

I installed Google Test on my system with sudo apt-get install libgtest-dev and the Fixture I'm working on doesn't have a main() and can be build with:

g++ unitTest.cpp -o unitTest /usr/src/gtest/src/gtest_main.cc /usr/src/gtest/src/gtest-all.cc -I /usr/include -I /usr/src/gtest -L /usr/local/lib -lpthread

Answer 2

Just as a reference I have a docker system setup with g++ and gtest which works properly. I provide all the files here for future reference:

Dockerfile

FROM gcc:9.2.0

WORKDIR /usr/src/app

RUN apt-get -qq update \
    && apt-get -qq install --no-install-recommends cmake \
    && apt-get clean \
    && rm -rf /var/lib/apt/lists/*

RUN git clone --depth=1 -b master https://github.com/google/googletest.git
RUN mkdir googletest/build

WORKDIR /usr/src/app/googletest/build

RUN cmake .. \
    && make \
    && make install \
    && rm -rf /usr/src/app/googletest

WORKDIR /usr/src/app

COPY . .
RUN mkdir obj

RUN make

CMD [ "./main" ]

Makefile

CXX = g++
CXXFLAGS = -std=c++17 -Wall -I h -I /usr/local/include/gtest/ -c
LXXFLAGS = -std=c++17 -I h -pthread
OBJECTS = ./obj/program.o ./obj/main.o ./obj/program_unittest.o
GTEST = /usr/local/lib/libgtest.a
TARGET = main


$(TARGET): $(OBJECTS)
    $(CXX) $(LXXFLAGS) -o $(TARGET) $(OBJECTS) $(GTEST)
./obj/program.o: ./cpp/program.cpp
    $(CXX) $(CXXFLAGS) ./cpp/program.cpp -o ./obj/program.o
./obj/program_unittest.o: ./cpp/program_unittest.cpp
    $(CXX) $(CXXFLAGS) ./cpp/program_unittest.cpp -o ./obj/program_unittest.o
./obj/main.o: ./cpp/main.cpp
    $(CXX) $(CXXFLAGS) ./cpp/main.cpp -o ./obj/main.o
clean:
    rm -fv $(TARGET) $(OBJECTS)

cpp/maincpp

#include <iostream>
#include "program.h"
#include "gtest/gtest.h"

int main(int argc, char **argv)
{
    ::testing::InitGoogleTest(&argc, argv);
    std::cout << "RUNNING TESTS ..." << std::endl;
    int ret{RUN_ALL_TESTS()};
    if (!ret)
        std::cout << "<<<SUCCESS>>>" << std::endl;
    else
        std::cout << "FAILED" << std::endl;
    return 0;
}

cpp/program.cpp

#include "program.h"

// Returns n! (the factorial of n).  For negative n, n! is defined to be 1.
int Factorial(int n)
{
    int result = 1;
    for (int i = 1; i <= n; i++)
    {
        result *= i;
    }

    return result;
}

// Returns true if and only if n is a prime number.
bool IsPrime(int n)
{
    // Trivial case 1: small numbers
    if (n <= 1)
        return false;

    // Trivial case 2: even numbers
    if (n % 2 == 0)
        return n == 2;

    // Now, we have that n is odd and n >= 3.

    // Try to divide n by every odd number i, starting from 3
    for (int i = 3;; i += 2)
    {
        // We only have to try i up to the square root of n
        if (i > n / i)
            break;

        // Now, we have i <= n/i < n.
        // If n is divisible by i, n is not prime.
        if (n % i == 0)
            return false;
    }

    // n has no integer factor in the range (1, n), and thus is prime.
    return true;
}

cpp/program_unittest.cpp

#include <limits.h>
#include "program.h"
#include "gtest/gtest.h"
namespace
{

// Tests Factorial().

// Tests factorial of negative numbers.
TEST(FactorialTest, Negative)
{
    // This test is named "Negative", and belongs to the "FactorialTest"
    // test case.
    EXPECT_EQ(1, Factorial(-5));
    EXPECT_EQ(1, Factorial(-1));
    EXPECT_GT(Factorial(-10), 0);

}

// Tests factorial of 0.
TEST(FactorialTest, Zero)
{
    EXPECT_EQ(1, Factorial(0));
}

// Tests factorial of positive numbers.
TEST(FactorialTest, Positive)
{
    EXPECT_EQ(1, Factorial(1));
    EXPECT_EQ(2, Factorial(2));
    EXPECT_EQ(6, Factorial(3));
    EXPECT_EQ(40320, Factorial(8));
}

// Tests IsPrime()

// Tests negative input.
TEST(IsPrimeTest, Negative)
{
    // This test belongs to the IsPrimeTest test case.

    EXPECT_FALSE(IsPrime(-1));
    EXPECT_FALSE(IsPrime(-2));
    EXPECT_FALSE(IsPrime(INT_MIN));
}

// Tests some trivial cases.
TEST(IsPrimeTest, Trivial)
{
    EXPECT_FALSE(IsPrime(0));
    EXPECT_FALSE(IsPrime(1));
    EXPECT_TRUE(IsPrime(2));
    EXPECT_TRUE(IsPrime(3));
}

// Tests positive input.
TEST(IsPrimeTest, Positive)
{
    EXPECT_FALSE(IsPrime(4));
    EXPECT_TRUE(IsPrime(5));
    EXPECT_FALSE(IsPrime(6));
    EXPECT_TRUE(IsPrime(23));
}

h/program.h

#ifndef GTEST_PROGRAM_H_
#define GTEST_PROGRAM_H_

// Returns n! (the factorial of n).  For negative n, n! is defined to be 1.
int Factorial(int n);

// Returns true if and only if n is a prime number.
bool IsPrime(int n);

#endif // GTEST_PROGRAM_H_

cpp/program.cpp and h/program.h files are from the googletest repo sample 1. Dockerfile is adapted from here.