Function diffTest

test/test.js:54–75

(imgPath1, imgPath2, diffPath, options, expectedMismatch)

});

function diffTest(imgPath1, imgPath2, diffPath, options, expectedMismatch) {
    const name = `comparing ${imgPath1} to ${imgPath2}, ${JSON.stringify(options)}`;

    test(name, () => {
        const img1 = readImage(imgPath1);
        const img2 = readImage(imgPath2);
        const {width, height} = img1;
        const diff = new PNG({width, height});

        const mismatch = match(img1.data, img2.data, diff.data, width, height, options);
        const mismatch2 = match(img1.data, img2.data, null, width, height, options);

        if (process.env.UPDATE) {
            writeImage(diffPath, diff);
        } else {
            const expectedDiff = readImage(diffPath);
            assert.ok(diff.data.equals(expectedDiff.data), 'diff image');
        }
        assert.equal(mismatch, expectedMismatch, 'number of mismatched pixels');
        assert.equal(mismatch, mismatch2, 'number of mismatched pixels without diff');
    });
}

function readImage(name) {
    return PNG.sync.read(fs.readFileSync(new URL(`fixtures/${name}.png`, import.meta.url)));