Rewiring your brain with test driven thinking in C++ - Phil Nash - Meeting C++ 2023

tdk.cpp

#include <string>
#include <string_view>
#include <catch2/catch_test_macros.hpp>

std::string left_pad(std::string_view str, std::size_t min_len) {
    auto const pad_len = std::max<int>(0, min_len-str.length()); 
    return std::string(pad_len, ' ') + std::string(str);
}

TEST_CASE("left_pad") {
    REQUIRE(left_pad("", 0) == "");
    REQUIRE(left_pad("a", 0) == "a");
    REQUIRE(left_pad("", 1) == " ");
    REQUIRE(left_pad("", 2) == "  ");
    REQUIRE(left_pad("abc", 5) == "  abc");
}

https://godbolt.org/z/hcrxTesf5