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Merged
bajtos merged 2 commits into from
Sep 26, 2019
Merged

Improve snapshot matcher #3776

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e14934b
feat(cli): print help on updating snapshots when some snapshots were …
bajtos Sep 20, 2019
f3e754b
feat(cli): write snapshot files in parallel
bajtos Sep 20, 2019
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35 changes: 27 additions & 8 deletions packages/cli/test/snapshot-matcher.js
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@ This is an initial experimental version. In the (near) future, we should
move this file to a standalone package so that all Mocha users can use it.
*/

const chalk = require('chalk');
const assert = require('assert');
const path = require('path');

Expand Down Expand Up @@ -43,6 +44,7 @@ module.exports = {
*/
function initializeSnapshots(snapshotDir) {
let currentTest;
let snapshotErrors = false;

beforeEach(function setupSnapshots() {
// eslint-disable-next-line no-invalid-this
Expand All @@ -51,17 +53,34 @@ function initializeSnapshots(snapshotDir) {
});

if (!process.env.UPDATE_SNAPSHOTS) {
process.on('exit', function printSnapshotHelp() {
if (!snapshotErrors) return;
console.log(
chalk.red(`
Some of the snapshot-based tests have failed. Please carefully inspect
the differences to prevent possible regressions. If the changes are
intentional, run the tests again with \`UPDATE_SNAPSHOTS=1\` environment
variable to update snapshots.
`),
);
});
return function expectToMatchSnapshot(actual) {
matchSnapshot(snapshotDir, currentTest, actual);
try {
matchSnapshot(snapshotDir, currentTest, actual);
} catch (err) {
snapshotErrors = true;
throw err;
}
};
}

const snapshots = Object.create(null);
after(function updateSnapshots() {
for (const f in snapshots) {
after(async function updateSnapshots() {
const tasks = Object.entries(snapshots).map(([f, data]) => {
const snapshotFile = buildSnapshotFilePath(snapshotDir, f);
writeSnapshotData(snapshotFile, snapshots[f]);
}
return writeSnapshotData(snapshotFile, data);
});
await Promise.all(tasks);
});

return function expectToRecordSnapshot(actual) {
Expand All @@ -83,7 +102,7 @@ function matchSnapshot(snapshotDir, currentTest, actualValue) {
if (!(key in snapshotData)) {
throw new Error(
`No snapshot found for ${JSON.stringify(key)}.\n` +
'Run the tests with UPDATE_SNAPSHOTS=1 in the environment ' +
'Run the tests with `UPDATE_SNAPSHOTS=1` environment variable ' +
'to create and update snapshot files.',
);
}
Expand Down Expand Up @@ -153,7 +172,7 @@ function loadSnapshotData(snapshotFile) {
if (err.code === 'MODULE_NOT_FOUND') {
throw new Error(
`Snapshot file ${snapshotFile} was not found.\n` +
'Run the tests with UPDATE_SNAPSHOTS=1 in the environment ' +
'Run the tests with `UPDATE_SNAPSHOTS=1` environment variable ' +
'to create and update snapshot files.',
);
}
Expand Down Expand Up @@ -182,7 +201,7 @@ function writeSnapshotData(snapshotFile, snapshots) {

const content = header + entries.join('\n');
mkdirp.sync(path.dirname(snapshotFile));
writeFileAtomic.sync(snapshotFile, content, {encoding: 'utf-8'});
return writeFileAtomic(snapshotFile, content, {encoding: 'utf-8'});
}

function buildSnapshotCode(key, value) {
Expand Down