catcrafts.net/tests/ShouldBuildMediaLadders/main.cpp

/*
catcrafts.net
Copyright (C) 2026 Catcrafts

The source code of this website is made available for viewing purposes only.
No permission is granted to copy, modify, distribute, or create derivative works.
*/

// The format ladder. One <picture>/<video> builder serves both the cards and
// the post bodies, so these assertions cover every image and video the site
// emits — and the ordering ones matter: a browser takes the FIRST source it
// understands, so a mis-ordered ladder silently serves the wrong tier to
// everyone rather than failing visibly.

import std;
import Catcrafts.Shared;

using namespace Catcrafts;

namespace {

int failures = 0;

void Check(bool ok, std::string_view what, std::string_view got = {}) {
    if (ok) return;
    ++failures;
    std::println(std::cerr, "FAIL: {}{}{}", what,
                 got.empty() ? "" : "  got: ", got);
}

void CheckEq(const Html::SafeHtml& actual, std::string_view expected, std::string_view what) {
    Check(actual.View() == expected, what, actual.View());
}

} // namespace

int main() {
    auto img = [](std::string src, std::string avif, std::string png,
                  std::int64_t w = 0, std::int64_t h = 0) {
        PostMedia m;
        m.src = std::move(src);
        m.kind = "image";
        m.avif = std::move(avif);
        m.fallback = std::move(png);
        m.width = w;
        m.height = h;
        return m;
    };

    // The full ladder: AVIF, then the mirrored original, then the PNG the <img>
    // itself points at. Exactly one of the three is ever fetched.
    CheckEq(Media::Tag(img("/media/x.webp", "/media/x.avif", "/media/x.png", 800, 600)),
            R"(<picture><source srcset="/media/x.avif" type="image/avif">)"
            R"(<source srcset="/media/x.webp" type="image/webp">)"
            R"(<img class="post-media__item" loading="lazy" decoding="async" alt="")"
            R"( src="/media/x.png" width="800" height="600"></picture>)",
            "media: image ladder is avif, original, png");

    // Alt text reaches the <img>, not the <picture> — a screen reader reads the
    // img, and an alt on the wrapper is invisible to it.
    Check(Media::Tag(img("/media/x.webp", "/media/x.avif", "/media/x.png"), "a cat")
              .View().find(R"(alt="a cat" src="/media/x.png")") != std::string_view::npos,
          "media: alt lands on the img");

    // Degradation, one tier at a time. Each of these is a real state: no
    // encoder on the build host, a source that was already PNG, a body image
    // whose download failed so there is nothing but the original URL.
    CheckEq(Media::Tag(img("/media/x.webp", "", "/media/x.png")),
            R"(<picture><source srcset="/media/x.webp" type="image/webp">)"
            R"(<img class="post-media__item" loading="lazy" decoding="async" alt="")"
            R"( src="/media/x.png"></picture>)",
            "media: no avif still offers the original above the png");
    CheckEq(Media::Tag(img("/media/x.webp", "/media/x.avif", "")),
            R"(<picture><source srcset="/media/x.avif" type="image/avif">)"
            R"(<img class="post-media__item" loading="lazy" decoding="async" alt="")"
            R"( src="/media/x.webp"></picture>)",
            "media: no png leaves the original as the base");
    CheckEq(Media::Tag(img("/media/x.webp", "", "")),
            R"(<img class="post-media__item" loading="lazy" decoding="async" alt="")"
            R"( src="/media/x.webp">)",
            "media: no renditions is a bare img, as before any of this existed");
    // A source that is already PNG is its own fallback, and must not be
    // offered twice — once as a <source> and once as the <img>.
    CheckEq(Media::Tag(img("/media/x.png", "/media/x.avif", "/media/x.png")),
            R"(<picture><source srcset="/media/x.avif" type="image/avif">)"
            R"(<img class="post-media__item" loading="lazy" decoding="async" alt="")"
            R"( src="/media/x.png"></picture>)",
            "media: a png source is not also listed as a source");
    // Likewise a source that is already AVIF.
    Check(Media::Tag(img("/media/x.avif", "/media/x.avif", "/media/x.png"))
              .View().find("image/avif\"><source") == std::string_view::npos,
          "media: an avif source is not listed twice");

    // A URL is still a URL: the scheme allowlist applies to srcset exactly as
    // it does to src, or the ladder becomes a way around it.
    Check(Media::Tag(img("/media/x.webp", "javascript:alert(1)", "/media/x.png"))
              .View().find(R"(srcset="#")") != std::string_view::npos,
          "media: a hostile srcset is neutralised");

    // Video is unchanged by any of this and must stay so.
    {
        PostMedia v;
        v.src = "/media/v.mp4";
        v.kind = "video";
        v.poster = "/media/v.webp";
        v.fallback = "/media/v.h264.mp4";
        const auto out = Media::Tag(v);
        Check(out.View().starts_with("<video class=\"post-media__item\" controls preload=\"metadata\""),
              "media: video is still a video", out.View());
        Check(out.View().find("codecs=av01") != std::string_view::npos
                  && out.View().find(R"(<source src="/media/v.h264.mp4" type="video/mp4">)")
                         != std::string_view::npos,
              "media: AV1 then H.264, in that order");
        Check(out.View().find("<picture>") == std::string_view::npos,
              "media: a video is not wrapped in a picture");
    }

    // A path with no record renders from the path alone — the mirror failed,
    // and showing the picture beats dropping the paragraph's subject.
    {
        const std::array<PostMedia, 1> known{
            img("/media/x.webp", "/media/x.avif", "/media/x.png") };
        Check(Media::Find(known, "/media/x.webp") != nullptr, "media: found by src");
        Check(Media::Find(known, "/media/nope.webp") == nullptr, "media: unknown src");
        const PostMedia guessed = Media::Describe(known, "https://i.example/a.webp");
        Check(guessed.kind == "image" && guessed.avif.empty(),
              "media: an unmirrored image is described from its path");
        Check(Media::Describe(known, "https://i.example/a.mp4").kind == "video",
              "media: an unmirrored video is recognised as one");
    }

    if (failures != 0) {
        std::println(std::cerr, "{} check(s) failed", failures);
        return 1;
    }
    return 0;
}