u

test/compare.mjs

@@ -159,13 +159,17 @@ function toRgba(parsed) {
   return out;
 }
 
-function compareFiles(refFile, curFile) {
-  const ref = parsePng(fs.readFileSync(refFile));
-  const cur = parsePng(fs.readFileSync(curFile));
+export function compareBuffers(refBuf, curBuf, { tolerance = TOLERANCE, channelTol = CHANNEL_TOL } = {}) {
+  const ref = parsePng(refBuf);
+  const cur = parsePng(curBuf);
   if (ref.width !== cur.width || ref.height !== cur.height) {
     return {
       ok: false,
       reason: `size mismatch ref=${ref.width}x${ref.height} cur=${cur.width}x${cur.height}`,
+      frac: 1,
+      maxDelta: 255,
+      diffPixels: ref.width * ref.height,
+      totalPixels: ref.width * ref.height,
     };
   }
   const a = toRgba(ref);
@@ -182,7 +186,7 @@ function compareFiles(refFile, curFile) {
       Math.abs(a[o + 2] - b[o + 2]),
     );
     if (d > maxDelta) maxDelta = d;
-    if (d > CHANNEL_TOL) {
+    if (d > channelTol) {
       diff++;
       diffImg[o] = 255;
       diffImg[o + 1] = 0;
@@ -199,7 +203,7 @@ function compareFiles(refFile, curFile) {
   }
   const frac = diff / total;
   return {
-    ok: frac <= TOLERANCE,
+    ok: frac <= tolerance,
     diffPixels: diff,
     totalPixels: total,
     frac,
@@ -208,6 +212,12 @@ function compareFiles(refFile, curFile) {
   };
 }
 
+export function compareFiles(refFile, curFile, opts = {}) {
+  return compareBuffers(fs.readFileSync(refFile), fs.readFileSync(curFile), opts);
+}
+
+export { parsePng, toRgba, encodePng };
+
 function main() {
   if (!fs.existsSync(REF_DIR)) {
     console.error(`[compare] no reference dir ${REF_DIR} — run: npm run rig:reference`);
@@ -260,4 +270,7 @@ function main() {
   console.log(`[compare] all ${files.length} screenshots match (tolerance ${(TOLERANCE * 100).toFixed(2)}%, channel±${CHANNEL_TOL})`);
 }
 
-main();
+const isMain = process.argv[1] && fileURLToPath(import.meta.url) === path.resolve(process.argv[1]);
+if (isMain) {
+  main();
+}