add initial unit test for {fmt} testing only conversions frequently used by LAMMPS

add_executable(test_utils test_utils.cpp)

target_link_libraries(test_utils PRIVATE lammps GTest::GMockMain GTest::GMock GTest::GTest)

add_test(Utils test_utils)

add_executable(test_fmtlib test_fmtlib.cpp)

target_link_libraries(test_fmtlib PRIVATE lammps GTest::GMockMain GTest::GMock GTest::GTest)

add_test(FmtLib test_fmtlib)

#include "lmptype.h"

#include "gtest/gtest.h"

#include "gmock/gmock.h"

#include "fmt/format.h"

#include <string>

using namespace LAMMPS_NS;

using ::testing::Eq;

// this tests a subset of {fmt} that is most relevant to LAMMPS

TEST(Fmtlib, insert_string) {

    const char word[] = "word";

    auto text = fmt::format("word {}",word);

    ASSERT_THAT(text, Eq("word word"));

}

TEST(Fmtlib, insert_int) {

    const int word = 333;

    auto text = fmt::format("word {}",word);

    ASSERT_THAT(text, Eq("word 333"));

}

TEST(Fmtlib, insert_neg_int) {

    const int word = -333;

    auto text = fmt::format("word {}",word);

    ASSERT_THAT(text, Eq("word -333"));

}

TEST(Fmtlib, insert_double) {

    const double word = 1.5;

    auto text = fmt::format("word {}",word);

    ASSERT_THAT(text, Eq("word 1.5"));

}

TEST(Fmtlib, insert_neg_double) {

    const double word = -1.5;

    auto text = fmt::format("word {}",word);

    ASSERT_THAT(text, Eq("word 1.5"));

}