Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

5 files changed, 656 insertions, 0 deletions

diff --git a/vendor/qoi/tests/common.rs b/vendor/qoi/tests/common.rs
new file mode 100644
index 0000000..cc1eff1
--- /dev/null
+++ b/vendor/qoi/tests/common.rs
@@ -0,0 +1,12 @@
+#[allow(unused)]
+pub fn hash<const N: usize>(px: [u8; N]) -> u8 {
+    let r = px[0];
+    let g = px[1];
+    let b = px[2];
+    let a = if N >= 4 { px[3] } else { 0xff };
+    let rm = r.wrapping_mul(3);
+    let gm = g.wrapping_mul(5);
+    let bm = b.wrapping_mul(7);
+    let am = a.wrapping_mul(11);
+    rm.wrapping_add(gm).wrapping_add(bm).wrapping_add(am) % 64
+}
diff --git a/vendor/qoi/tests/test_chunks.rs b/vendor/qoi/tests/test_chunks.rs
new file mode 100644
index 0000000..d465140
--- /dev/null
+++ b/vendor/qoi/tests/test_chunks.rs
@@ -0,0 +1,211 @@
+mod common;
+
+use bytemuck::{cast_slice, Pod};
+
+use qoi::consts::{
+    QOI_HEADER_SIZE, QOI_OP_DIFF, QOI_OP_INDEX, QOI_OP_LUMA, QOI_OP_RGB, QOI_OP_RGBA, QOI_OP_RUN,
+    QOI_PADDING_SIZE,
+};
+use qoi::{decode_to_vec, encode_to_vec};
+
+use self::common::hash;
+
+fn test_chunk<P, E, const N: usize>(pixels: P, expected: E)
+where
+    P: AsRef<[[u8; N]]>,
+    E: AsRef<[u8]>,
+    [u8; N]: Pod,
+{
+    let pixels = pixels.as_ref();
+    let expected = expected.as_ref();
+    let pixels_raw = cast_slice::<_, u8>(pixels);
+    let encoded = encode_to_vec(pixels_raw, pixels.len() as _, 1).unwrap();
+    let decoded = decode_to_vec(&encoded).unwrap().1;
+    assert_eq!(pixels_raw, decoded.as_slice(), "roundtrip failed (encoded={:?}))", encoded);
+    assert!(encoded.len() >= expected.len() + QOI_HEADER_SIZE + QOI_PADDING_SIZE);
+    assert_eq!(&encoded[QOI_HEADER_SIZE..][..expected.len()], expected);
+}
+
+#[test]
+fn test_encode_rgb_3ch() {
+    test_chunk([[11, 121, 231]], [QOI_OP_RGB, 11, 121, 231]);
+}
+
+#[test]
+fn test_encode_rgb_4ch() {
+    test_chunk([[11, 121, 231, 0xff]], [QOI_OP_RGB, 11, 121, 231]);
+}
+
+#[test]
+fn test_encode_rgba() {
+    test_chunk([[11, 121, 231, 55]], [QOI_OP_RGBA, 11, 121, 231, 55]);
+}
+
+#[test]
+fn test_encode_run_start_len1to62_3ch() {
+    for n in 1..=62 {
+        let mut v = vec![[0, 0, 0]; n];
+        v.push([11, 22, 33]);
+        test_chunk(v, [QOI_OP_RUN | (n as u8 - 1), QOI_OP_RGB]);
+    }
+}
+
+#[test]
+fn test_encode_run_start_len1to62_4ch() {
+    for n in 1..=62 {
+        let mut v = vec![[0, 0, 0, 0xff]; n];
+        v.push([11, 22, 33, 44]);
+        test_chunk(v, [QOI_OP_RUN | (n as u8 - 1), QOI_OP_RGBA]);
+    }
+}
+
+#[test]
+fn test_encode_run_start_63to124_3ch() {
+    for n in 63..=124 {
+        let mut v = vec![[0, 0, 0]; n];
+        v.push([11, 22, 33]);
+        test_chunk(v, [QOI_OP_RUN | 61, QOI_OP_RUN | (n as u8 - 63), QOI_OP_RGB]);
+    }
+}
+
+#[test]
+fn test_encode_run_start_len63to124_4ch() {
+    for n in 63..=124 {
+        let mut v = vec![[0, 0, 0, 0xff]; n];
+        v.push([11, 22, 33, 44]);
+        test_chunk(v, [QOI_OP_RUN | 61, QOI_OP_RUN | (n as u8 - 63), QOI_OP_RGBA]);
+    }
+}
+
+#[test]
+fn test_encode_run_end_3ch() {
+    let px = [11, 33, 55];
+    test_chunk(
+        [[1, 99, 2], px, px, px],
+        [QOI_OP_RGB, 1, 99, 2, QOI_OP_RGB, px[0], px[1], px[2], QOI_OP_RUN | 1],
+    );
+}
+
+#[test]
+fn test_encode_run_end_4ch() {
+    let px = [11, 33, 55, 77];
+    test_chunk(
+        [[1, 99, 2, 3], px, px, px],
+        [QOI_OP_RGBA, 1, 99, 2, 3, QOI_OP_RGBA, px[0], px[1], px[2], px[3], QOI_OP_RUN | 1],
+    );
+}
+
+#[test]
+fn test_encode_run_mid_3ch() {
+    let px = [11, 33, 55];
+    test_chunk(
+        [[1, 99, 2], px, px, px, [1, 2, 3]],
+        [QOI_OP_RGB, 1, 99, 2, QOI_OP_RGB, px[0], px[1], px[2], QOI_OP_RUN | 1],
+    );
+}
+
+#[test]
+fn test_encode_run_mid_4ch() {
+    let px = [11, 33, 55, 77];
+    test_chunk(
+        [[1, 99, 2, 3], px, px, px, [1, 2, 3, 4]],
+        [QOI_OP_RGBA, 1, 99, 2, 3, QOI_OP_RGBA, px[0], px[1], px[2], px[3], QOI_OP_RUN | 1],
+    );
+}
+
+#[test]
+fn test_encode_index_3ch() {
+    let px = [101, 102, 103];
+    test_chunk(
+        [px, [1, 2, 3], px],
+        [QOI_OP_RGB, 101, 102, 103, QOI_OP_RGB, 1, 2, 3, QOI_OP_INDEX | hash(px)],
+    );
+}
+
+#[test]
+fn test_encode_index_4ch() {
+    let px = [101, 102, 103, 104];
+    test_chunk(
+        [px, [1, 2, 3, 4], px],
+        [QOI_OP_RGBA, 101, 102, 103, 104, QOI_OP_RGBA, 1, 2, 3, 4, QOI_OP_INDEX | hash(px)],
+    );
+}
+
+#[test]
+fn test_encode_index_zero_3ch() {
+    let px = [0, 0, 0];
+    test_chunk([[101, 102, 103], px], [QOI_OP_RGB, 101, 102, 103, QOI_OP_RGB, 0, 0, 0]);
+}
+
+#[test]
+fn test_encode_index_zero_0x00_4ch() {
+    let px = [0, 0, 0, 0];
+    test_chunk(
+        [[101, 102, 103, 104], px],
+        [QOI_OP_RGBA, 101, 102, 103, 104, QOI_OP_INDEX | hash(px)],
+    );
+}
+
+#[test]
+fn test_encode_index_zero_0xff_4ch() {
+    let px = [0, 0, 0, 0xff];
+    test_chunk(
+        [[101, 102, 103, 104], px],
+        [QOI_OP_RGBA, 101, 102, 103, 104, QOI_OP_RGBA, 0, 0, 0, 0xff],
+    );
+}
+
+#[test]
+fn test_encode_diff() {
+    for x in 0..8_u8 {
+        let x = [x.wrapping_sub(5), x.wrapping_sub(4), x.wrapping_sub(3)];
+        for dr in 0..3 {
+            for dg in 0..3 {
+                for db in 0..3 {
+                    if dr != 2 || dg != 2 || db != 2 {
+                        let r = x[0].wrapping_add(dr).wrapping_sub(2);
+                        let g = x[1].wrapping_add(dg).wrapping_sub(2);
+                        let b = x[2].wrapping_add(db).wrapping_sub(2);
+                        let d = QOI_OP_DIFF | dr << 4 | dg << 2 | db;
+                        test_chunk(
+                            [[1, 99, 2], x, [r, g, b]],
+                            [QOI_OP_RGB, 1, 99, 2, QOI_OP_RGB, x[0], x[1], x[2], d],
+                        );
+                        test_chunk(
+                            [[1, 99, 2, 0xff], [x[0], x[1], x[2], 9], [r, g, b, 9]],
+                            [QOI_OP_RGB, 1, 99, 2, QOI_OP_RGBA, x[0], x[1], x[2], 9, d],
+                        );
+                    }
+                }
+            }
+        }
+    }
+}
+
+#[test]
+fn test_encode_luma() {
+    for x in (0..200_u8).step_by(4) {
+        let x = [x.wrapping_mul(3), x.wrapping_sub(5), x.wrapping_sub(7)];
+        for dr_g in (0..16).step_by(4) {
+            for dg in (0..64).step_by(8) {
+                for db_g in (0..16).step_by(4) {
+                    if dr_g != 8 || dg != 32 || db_g != 8 {
+                        let r = x[0].wrapping_add(dr_g).wrapping_add(dg).wrapping_sub(40);
+                        let g = x[1].wrapping_add(dg).wrapping_sub(32);
+                        let b = x[2].wrapping_add(db_g).wrapping_add(dg).wrapping_sub(40);
+                        let d1 = QOI_OP_LUMA | dg;
+                        let d2 = (dr_g << 4) | db_g;
+                        test_chunk(
+                            [[1, 99, 2], x, [r, g, b]],
+                            [QOI_OP_RGB, 1, 99, 2, QOI_OP_RGB, x[0], x[1], x[2], d1, d2],
+                        );
+                        test_chunk(
+                            [[1, 99, 2, 0xff], [x[0], x[1], x[2], 9], [r, g, b, 9]],
+                            [QOI_OP_RGB, 1, 99, 2, QOI_OP_RGBA, x[0], x[1], x[2], 9, d1, d2],
+                        );
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/vendor/qoi/tests/test_gen.rs b/vendor/qoi/tests/test_gen.rs
new file mode 100644
index 0000000..08767d4
--- /dev/null
+++ b/vendor/qoi/tests/test_gen.rs
@@ -0,0 +1,313 @@
+mod common;
+
+use bytemuck::cast_slice;
+use std::borrow::Cow;
+use std::fmt::Debug;
+
+use cfg_if::cfg_if;
+use rand::{
+    distributions::{Distribution, Standard},
+    rngs::StdRng,
+    Rng, SeedableRng,
+};
+
+use libqoi::{qoi_decode, qoi_encode};
+use qoi::consts::{
+    QOI_HEADER_SIZE, QOI_MASK_2, QOI_OP_DIFF, QOI_OP_INDEX, QOI_OP_LUMA, QOI_OP_RGB, QOI_OP_RGBA,
+    QOI_OP_RUN, QOI_PADDING_SIZE,
+};
+use qoi::{decode_header, decode_to_vec, encode_to_vec};
+
+use self::common::hash;
+
+struct GenState<const N: usize> {
+    index: [[u8; N]; 64],
+    pixels: Vec<u8>,
+    prev: [u8; N],
+    len: usize,
+}
+
+impl<const N: usize> GenState<N> {
+    pub fn with_capacity(capacity: usize) -> Self {
+        Self {
+            index: [[0; N]; 64],
+            pixels: Vec::with_capacity(capacity * N),
+            prev: Self::zero(),
+            len: 0,
+        }
+    }
+    pub fn write(&mut self, px: [u8; N]) {
+        self.index[hash(px) as usize] = px;
+        for i in 0..N {
+            self.pixels.push(px[i]);
+        }
+        self.prev = px;
+        self.len += 1;
+    }
+
+    pub fn pick_from_index(&self, rng: &mut impl Rng) -> [u8; N] {
+        self.index[rng.gen_range(0_usize..64)]
+    }
+
+    pub fn zero() -> [u8; N] {
+        let mut px = [0; N];
+        if N >= 4 {
+            px[3] = 0xff;
+        }
+        px
+    }
+}
+
+struct ImageGen {
+    p_new: f64,
+    p_index: f64,
+    p_repeat: f64,
+    p_diff: f64,
+    p_luma: f64,
+}
+
+impl ImageGen {
+    pub fn new_random(rng: &mut impl Rng) -> Self {
+        let p: [f64; 6] = rng.gen();
+        let t = p.iter().sum::<f64>();
+        Self {
+            p_new: p[0] / t,
+            p_index: p[1] / t,
+            p_repeat: p[2] / t,
+            p_diff: p[3] / t,
+            p_luma: p[4] / t,
+        }
+    }
+
+    pub fn generate(&self, rng: &mut impl Rng, channels: usize, min_len: usize) -> Vec<u8> {
+        match channels {
+            3 => self.generate_const::<_, 3>(rng, min_len),
+            4 => self.generate_const::<_, 4>(rng, min_len),
+            _ => panic!(),
+        }
+    }
+
+    fn generate_const<R: Rng, const N: usize>(&self, rng: &mut R, min_len: usize) -> Vec<u8>
+    where
+        Standard: Distribution<[u8; N]>,
+    {
+        let mut s = GenState::<N>::with_capacity(min_len);
+        let zero = GenState::<N>::zero();
+
+        while s.len < min_len {
+            let mut p = rng.gen_range(0.0..1.0);
+
+            if p < self.p_new {
+                s.write(rng.gen());
+                continue;
+            }
+            p -= self.p_new;
+
+            if p < self.p_index {
+                let px = s.pick_from_index(rng);
+                s.write(px);
+                continue;
+            }
+            p -= self.p_index;
+
+            if p < self.p_repeat {
+                let px = s.prev;
+                let n_repeat = rng.gen_range(1_usize..=70);
+                for _ in 0..n_repeat {
+                    s.write(px);
+                }
+                continue;
+            }
+            p -= self.p_repeat;
+
+            if p < self.p_diff {
+                let mut px = s.prev;
+                px[0] = px[0].wrapping_add(rng.gen_range(0_u8..4).wrapping_sub(2));
+                px[1] = px[1].wrapping_add(rng.gen_range(0_u8..4).wrapping_sub(2));
+                px[2] = px[2].wrapping_add(rng.gen_range(0_u8..4).wrapping_sub(2));
+                s.write(px);
+                continue;
+            }
+            p -= self.p_diff;
+
+            if p < self.p_luma {
+                let mut px = s.prev;
+                let vg = rng.gen_range(0_u8..64).wrapping_sub(32);
+                let vr = rng.gen_range(0_u8..16).wrapping_sub(8).wrapping_add(vg);
+                let vb = rng.gen_range(0_u8..16).wrapping_sub(8).wrapping_add(vg);
+                px[0] = px[0].wrapping_add(vr);
+                px[1] = px[1].wrapping_add(vg);
+                px[2] = px[2].wrapping_add(vb);
+                s.write(px);
+                continue;
+            }
+
+            s.write(zero);
+        }
+
+        s.pixels
+    }
+}
+
+fn format_encoded(encoded: &[u8]) -> String {
+    let header = decode_header(encoded).unwrap();
+    let mut data = &encoded[QOI_HEADER_SIZE..encoded.len() - QOI_PADDING_SIZE];
+    let mut s = format!("{}x{}:{} = [", header.width, header.height, header.channels.as_u8());
+    while !data.is_empty() {
+        let b1 = data[0];
+        data = &data[1..];
+        match b1 {
+            QOI_OP_RGB => {
+                s.push_str(&format!("rgb({},{},{})", data[0], data[1], data[2]));
+                data = &data[3..];
+            }
+            QOI_OP_RGBA => {
+                s.push_str(&format!("rgba({},{},{},{})", data[0], data[1], data[2], data[3]));
+                data = &data[4..];
+            }
+            _ => match b1 & QOI_MASK_2 {
+                QOI_OP_INDEX => s.push_str(&format!("index({})", b1 & 0x3f)),
+                QOI_OP_RUN => s.push_str(&format!("run({})", b1 & 0x3f)),
+                QOI_OP_DIFF => s.push_str(&format!(
+                    "diff({},{},{})",
+                    (b1 >> 4) & 0x03,
+                    (b1 >> 2) & 0x03,
+                    b1 & 0x03
+                )),
+                QOI_OP_LUMA => {
+                    let b2 = data[0];
+                    data = &data[1..];
+                    s.push_str(&format!("luma({},{},{})", (b2 >> 4) & 0x0f, b1 & 0x3f, b2 & 0x0f))
+                }
+                _ => {}
+            },
+        }
+        s.push_str(", ");
+    }
+    s.pop().unwrap();
+    s.pop().unwrap();
+    s.push(']');
+    s
+}
+
+fn check_roundtrip<E, D, VE, VD, EE, ED>(
+    msg: &str, mut data: &[u8], channels: usize, encode: E, decode: D,
+) where
+    E: Fn(&[u8], u32) -> Result<VE, EE>,
+    D: Fn(&[u8]) -> Result<VD, ED>,
+    VE: AsRef<[u8]>,
+    VD: AsRef<[u8]>,
+    EE: Debug,
+    ED: Debug,
+{
+    macro_rules! rt {
+        ($data:expr, $n:expr) => {
+            decode(encode($data, $n as _).unwrap().as_ref()).unwrap()
+        };
+    }
+    macro_rules! fail {
+        ($msg:expr, $data:expr, $decoded:expr, $encoded:expr, $channels:expr) => {
+            assert!(
+                false,
+                "{} roundtrip failed\n\n  image: {:?}\ndecoded: {:?}\nencoded: {}",
+                $msg,
+                cast_slice::<_, [u8; $channels]>($data.as_ref()),
+                cast_slice::<_, [u8; $channels]>($decoded.as_ref()),
+                format_encoded($encoded.as_ref()),
+            );
+        };
+    }
+
+    let mut n_pixels = data.len() / channels;
+    assert_eq!(n_pixels * channels, data.len());
+
+    // if all ok, return
+    // ... but if roundtrip check fails, try to reduce the example to the smallest we can find
+    if rt!(data, n_pixels).as_ref() == data {
+        return;
+    }
+
+    // try removing pixels from the beginning
+    while n_pixels > 1 {
+        let slice = &data[..data.len() - channels];
+        if rt!(slice, n_pixels - 1).as_ref() != slice {
+            data = slice;
+            n_pixels -= 1;
+        } else {
+            break;
+        }
+    }
+
+    // try removing pixels from the end
+    while n_pixels > 1 {
+        let slice = &data[channels..];
+        if rt!(slice, n_pixels - 1).as_ref() != slice {
+            data = slice;
+            n_pixels -= 1;
+        } else {
+            break;
+        }
+    }
+
+    // try removing pixels from the middle
+    let mut data = Cow::from(data);
+    let mut pos = 1;
+    while n_pixels > 1 && pos < n_pixels - 1 {
+        let mut vec = data.to_vec();
+        for _ in 0..channels {
+            vec.remove(pos * channels);
+        }
+        if rt!(vec.as_slice(), n_pixels - 1).as_ref() != vec.as_slice() {
+            data = Cow::from(vec);
+            n_pixels -= 1;
+        } else {
+            pos += 1;
+        }
+    }
+
+    let encoded = encode(data.as_ref(), n_pixels as _).unwrap();
+    let decoded = decode(encoded.as_ref()).unwrap();
+    assert_ne!(decoded.as_ref(), data.as_ref());
+    if channels == 3 {
+        fail!(msg, data, decoded, encoded, 3);
+    } else {
+        fail!(msg, data, decoded, encoded, 4);
+    }
+}
+
+#[test]
+fn test_generated() {
+    let mut rng = StdRng::seed_from_u64(0);
+
+    let mut n_pixels = 0;
+    while n_pixels < 20_000_000 {
+        let min_len = rng.gen_range(1..=5000);
+        let channels = rng.gen_range(3..=4);
+        let gen = ImageGen::new_random(&mut rng);
+        let img = gen.generate(&mut rng, channels, min_len);
+
+        let encode = |data: &[u8], size| encode_to_vec(data, size, 1);
+        let decode = |data: &[u8]| decode_to_vec(data).map(|r| r.1);
+        let encode_c = |data: &[u8], size| qoi_encode(data, size, 1, channels as _);
+        let decode_c = |data: &[u8]| qoi_decode(data, channels as _).map(|r| r.1);
+
+        check_roundtrip("qoi-rust -> qoi-rust", &img, channels as _, encode, decode);
+        check_roundtrip("qoi-rust -> qoi.h", &img, channels as _, encode, decode_c);
+        check_roundtrip("qoi.h -> qoi-rust", &img, channels as _, encode_c, decode);
+
+        let size = (img.len() / channels) as u32;
+        let encoded = encode(&img, size).unwrap();
+        let encoded_c = encode_c(&img, size).unwrap();
+        cfg_if! {
+            if #[cfg(feature = "reference")] {
+                let eq = encoded.as_slice() == encoded_c.as_ref();
+                assert!(eq, "qoi-rust [reference mode] doesn't match qoi.h");
+            } else {
+                let eq = encoded.len() == encoded_c.len();
+                assert!(eq, "qoi-rust [non-reference mode] length doesn't match qoi.h");
+            }
+        }
+
+        n_pixels += size;
+    }
+}
diff --git a/vendor/qoi/tests/test_misc.rs b/vendor/qoi/tests/test_misc.rs
new file mode 100644
index 0000000..720adf4
--- /dev/null
+++ b/vendor/qoi/tests/test_misc.rs
@@ -0,0 +1,6 @@
+#[test]
+fn test_new_encoder() {
+    // this used to fail due to `Bytes` not being `pub`
+    let arr = [0u8];
+    let _ = qoi::Decoder::new(&arr[..]);
+}
\ No newline at end of file
diff --git a/vendor/qoi/tests/test_ref.rs b/vendor/qoi/tests/test_ref.rs
new file mode 100644
index 0000000..59a7315
--- /dev/null
+++ b/vendor/qoi/tests/test_ref.rs
@@ -0,0 +1,114 @@
+use std::fs::{self, File};
+use std::path::{Path, PathBuf};
+
+use anyhow::{bail, Result};
+use cfg_if::cfg_if;
+use walkdir::{DirEntry, WalkDir};
+
+use qoi::{decode_to_vec, encode_to_vec};
+
+fn find_qoi_png_pairs(root: impl AsRef<Path>) -> Vec<(PathBuf, PathBuf)> {
+    let root = root.as_ref();
+
+    let get_ext =
+        |path: &Path| path.extension().unwrap_or_default().to_string_lossy().to_ascii_lowercase();
+    let check_qoi_png_pair = |path: &Path| {
+        let (qoi, png) = (path.to_path_buf(), path.with_extension("png"));
+        if qoi.is_file() && get_ext(&qoi) == "qoi" && png.is_file() {
+            Some((qoi, png))
+        } else {
+            None
+        }
+    };
+
+    let mut out = vec![];
+    if let Some(pair) = check_qoi_png_pair(root) {
+        out.push(pair);
+    } else if root.is_dir() {
+        out.extend(
+            WalkDir::new(root)
+                .follow_links(true)
+                .into_iter()
+                .filter_map(Result::ok)
+                .map(DirEntry::into_path)
+                .filter_map(|p| check_qoi_png_pair(&p)),
+        )
+    }
+    out
+}
+
+struct Image {
+    pub width: u32,
+    pub height: u32,
+    pub channels: u8,
+    pub data: Vec<u8>,
+}
+
+impl Image {
+    fn from_png(filename: &Path) -> Result<Self> {
+        let decoder = png::Decoder::new(File::open(filename)?);
+        let mut reader = decoder.read_info()?;
+        let mut buf = vec![0; reader.output_buffer_size()];
+        let info = reader.next_frame(&mut buf)?;
+        let bytes = &buf[..info.buffer_size()];
+        Ok(Self {
+            width: info.width,
+            height: info.height,
+            channels: info.color_type.samples() as u8,
+            data: bytes.to_vec(),
+        })
+    }
+}
+
+fn compare_slices(name: &str, desc: &str, result: &[u8], expected: &[u8]) -> Result<()> {
+    if result == expected {
+        Ok(())
+    } else {
+        if let Some(i) =
+            (0..result.len().min(expected.len())).position(|i| result[i] != expected[i])
+        {
+            bail!(
+                "{}: {} mismatch at byte {}: expected {:?}, got {:?}",
+                name,
+                desc,
+                i,
+                &expected[i..(i + 4).min(expected.len())],
+                &result[i..(i + 4).min(result.len())],
+            );
+        } else {
+            bail!(
+                "{}: {} length mismatch: expected {}, got {}",
+                name,
+                desc,
+                expected.len(),
+                result.len()
+            );
+        }
+    }
+}
+
+#[test]
+fn test_reference_images() -> Result<()> {
+    let pairs = find_qoi_png_pairs("assets");
+    assert!(!pairs.is_empty());
+
+    for (qoi_path, png_path) in &pairs {
+        let png_name = png_path.file_name().unwrap_or_default().to_string_lossy();
+        let img = Image::from_png(png_path)?;
+        println!("{} {} {} {}", png_name, img.width, img.height, img.channels);
+        let encoded = encode_to_vec(&img.data, img.width, img.height)?;
+        let expected = fs::read(qoi_path)?;
+        assert_eq!(encoded.len(), expected.len()); // this should match regardless
+        cfg_if! {
+            if #[cfg(feature = "reference")] {
+                compare_slices(&png_name, "encoding", &encoded, &expected)?;
+            }
+        }
+        let (_header1, decoded1) = decode_to_vec(&encoded)?;
+        let (_header2, decoded2) = decode_to_vec(&expected)?;
+        compare_slices(&png_name, "decoding [1]", &decoded1, &img.data)?;
+        compare_slices(&png_name, "decoding [2]", &decoded2, &img.data)?;
+    }
+
+    Ok(())
+}