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/**
* @license
* Copyright 2017 Google Inc.
* SPDX-License-Identifier: Apache-2.0
*/
import assert from 'assert';
import fs from 'fs';
import path from 'path';
import {diffLines} from 'diff';
import jpeg from 'jpeg-js';
import mime from 'mime';
import pixelmatch from 'pixelmatch';
import {PNG} from 'pngjs';
interface DiffFile {
diff: string | Buffer;
ext?: string;
}
const GoldenComparators = new Map<
string,
(
actualBuffer: string | Buffer,
expectedBuffer: string | Buffer,
mimeType: string
) => DiffFile | undefined
>();
const addSuffix = (
filePath: string,
suffix: string,
customExtension?: string
): string => {
const dirname = path.dirname(filePath);
const ext = path.extname(filePath);
const name = path.basename(filePath, ext);
return path.join(dirname, name + suffix + (customExtension || ext));
};
const compareImages = (
actualBuffer: string | Buffer,
expectedBuffer: string | Buffer,
mimeType: string
): DiffFile | undefined => {
assert(typeof actualBuffer !== 'string');
assert(typeof expectedBuffer !== 'string');
const actual =
mimeType === 'image/png'
? PNG.sync.read(actualBuffer)
: jpeg.decode(actualBuffer);
const expected =
mimeType === 'image/png'
? PNG.sync.read(expectedBuffer)
: jpeg.decode(expectedBuffer);
if (expected.width !== actual.width || expected.height !== actual.height) {
throw new Error(
`Sizes differ: expected image ${expected.width}px X ${expected.height}px, but got ${actual.width}px X ${actual.height}px.`
);
}
const diff = new PNG({width: expected.width, height: expected.height});
const count = pixelmatch(
expected.data,
actual.data,
diff.data,
expected.width,
expected.height,
{threshold: 0.1}
);
return count > 0 ? {diff: PNG.sync.write(diff)} : undefined;
};
const compareText = (
actual: string | Buffer,
expectedBuffer: string | Buffer
): DiffFile | undefined => {
assert(typeof actual === 'string');
const expected = expectedBuffer.toString('utf-8');
if (expected === actual) {
return;
}
const result = diffLines(expected, actual);
const html = result.reduce(
(text, change) => {
text += change.added
? `<span class='ins'>${change.value}</span>`
: change.removed
? `<span class='del'>${change.value}</span>`
: change.value;
return text;
},
`<link rel="stylesheet" href="file://${path.join(
__dirname,
'diffstyle.css'
)}">`
);
return {
diff: html,
ext: '.html',
};
};
GoldenComparators.set('image/png', compareImages);
GoldenComparators.set('image/jpeg', compareImages);
GoldenComparators.set('text/plain', compareText);
export const compare = (
goldenPath: string,
outputPath: string,
actual: string | Buffer,
goldenName: string
): {pass: true} | {pass: false; message: string} => {
goldenPath = path.normalize(goldenPath);
outputPath = path.normalize(outputPath);
const expectedPath = path.join(goldenPath, goldenName);
const actualPath = path.join(outputPath, goldenName);
const messageSuffix = `Output is saved in "${path.basename(
outputPath + '" directory'
)}`;
if (!fs.existsSync(expectedPath)) {
ensureOutputDir();
fs.writeFileSync(actualPath, actual);
return {
pass: false,
message: `${goldenName} is missing in golden results. ${messageSuffix}`,
};
}
const expected = fs.readFileSync(expectedPath);
const mimeType = mime.getType(goldenName);
assert(mimeType);
const comparator = GoldenComparators.get(mimeType);
if (!comparator) {
return {
pass: false,
message: `Failed to find comparator with type ${mimeType}: ${goldenName}`,
};
}
const result = comparator(actual, expected, mimeType);
if (!result) {
return {pass: true};
}
ensureOutputDir();
if (goldenPath === outputPath) {
fs.writeFileSync(addSuffix(actualPath, '-actual'), actual);
} else {
fs.writeFileSync(actualPath, actual);
// Copy expected to the output/ folder for convenience.
fs.writeFileSync(addSuffix(actualPath, '-expected'), expected);
}
if (result) {
const diffPath = addSuffix(actualPath, '-diff', result.ext);
fs.writeFileSync(diffPath, result.diff);
}
return {
pass: false,
message: `${goldenName} mismatch! ${messageSuffix}`,
};
function ensureOutputDir() {
if (!fs.existsSync(outputPath)) {
fs.mkdirSync(outputPath);
}
}
};
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