Projektaufbau, Tests und gute Praxis

mein-projekt/
├─ CMakeLists.txt
├─ src/
│  ├─ main.cpp
│  ├─ rechner.cpp
│  └─ rechner.hpp
├─ tests/
│  └─ test_rechner.cpp
└─ build/              (erzeugt, nicht ins Repository)

cmake_minimum_required(VERSION 3.20)
project(MeinProjekt LANGUAGES CXX)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

add_library(rechner src/rechner.cpp)
target_include_directories(rechner PUBLIC src)

add_executable(programm src/main.cpp)
target_link_libraries(programm PRIVATE rechner)
target_compile_options(programm PRIVATE -Wall -Wextra -Wpedantic)

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build
./build/programm
ctest --test-dir build          # Tests ausführen

// rechner.hpp
#pragma once

int addiere(int a, int b);

// rechner.cpp
#include "rechner.hpp"
int addiere(int a, int b) { return a + b; }

#include <iostream>
#include <string>
#include <cmath>

int fehler = 0;
#define PRUEFE(bedingung) do { \
    if (!(bedingung)) { ++fehler; std::cout << "FEHLER Zeile " << __LINE__ << ": " #bedingung "\n"; } \
    else std::cout << "ok: " #bedingung "\n"; } while (0)

bool istPalindrom(const std::string& s) {
    std::string t;
    for (unsigned char c : s) if (std::isalnum(c)) t += static_cast<char>(std::tolower(c));
    return std::equal(t.begin(), t.begin() + t.size() / 2, t.rbegin());
}

int main() {
    PRUEFE(istPalindrom("Anna"));
    PRUEFE(istPalindrom("Ein Esel lese nie"));
    PRUEFE(!istPalindrom("Hallo"));
    PRUEFE(istPalindrom(""));
    PRUEFE(std::abs(0.1 + 0.2 - 0.3) < 1e-9);
    std::cout << fehler << " Fehler\n";
    return fehler;
}

TEST_CASE("addiere") {
    REQUIRE(addiere(2, 3) == 5);
    REQUIRE(addiere(-1, 1) == 0);
}