gristlabs_grist-core/test/split-tests.js

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/**
* This module handles splitting tests for parallelizing them. This module is imported by any run
* of mocha, due by being listed in test/mocha.opts.
*
* It only does anything if TEST_SPLITS is set, which must have the form "3-of-8".
*
* If TEST_SPLITS is set to M-of-N, it is used to divide up all test suites in this mocha run into
* N groups, and runs the Mth of them. Note that M is 1-based, i.e. in [1..N] range. To have all
* tests run, each of the groups 1-of-N through N-of-N must run on the same total set of tests.
*
* The actual breaking into groups is informed by a timings file, defaulting to
* test/timings-all.txt. This has the format "<top-suite> <file-suite-title> <duration-in-ms>".
* Only those lines whose <top-suite> matches process.env.TEST_SUITE_FOR_TIMINGS will be used.
*
* The timings for test/timings-all.txt are prepared by our test reporter and written during
* Jenkins run as the timings/timings-all.txt artifact. After tests are added or changed, if
* timings may have changed significantly, it's good to update test/timings-all.txt, so that the
* parallel groups can be evened out as much as possible.
*/
const fs = require('fs');
const { assert } = require('chai');
const testSuite = process.env.TEST_SUITE_FOR_TIMINGS || "unset_suite";
const timingsFile = process.env.TIMINGS_FILE || "test/timings-all.txt";
exports.mochaHooks = {
beforeAll(done) {
const testSplits = process.env.TEST_SPLITS;
if (!testSplits) {
return done();
}
const match = testSplits.match(/^(\d+)-of-(\d+)$/);
if (!match) {
assert.fail(`Invalid test split spec '${testSplits}': use format 'N-of-M'`);
}
const group = Number(match[1]);
const groupCount = Number(match[2]);
if (!(group >= 1 && group <= groupCount)) {
assert.fail(`Invalid test split spec '${testSplits}': index must be in range 1..{groupCount}`);
}
const testParent = this.test.parent;
const timings = getTimings();
const groups = groupSuites(testParent.suites, timings, groupCount);
testParent.suites = groups[group - 1]; // Convert to a 0-based index.
console.log(`Split tests groups; will run group ${group} of ${groupCount}`);
done();
}
};
/**
* Read timings from timingsFile into a Map mapping file-suite-title to duration.
*/
function getTimings() {
const timings = new Map();
try {
const content = fs.readFileSync(timingsFile, {encoding: 'utf8'})
for (const line of content.split(/\r?\n/)) {
const [bigSuite, fileSuite, duration] = line.split(/\s+/);
if (bigSuite === testSuite && !isNaN(Number(duration))) {
timings.set(fileSuite, Number(duration));
}
}
} catch (e) {
if (e.code === 'ENOENT') {
console.warn(`No timings found in ${timingsFile}; proceeding without timings`);
} else {
throw e;
}
}
return timings;
}
/**
* Splits suites into groups and returns the list of them.
*
* The algorithm to group tests into suites starts goes one by one from longest to shortest,
* adding them to the least filled-up group.
*/
function groupSuites(suites, timings, groupCount) {
// Calculate a fallback value for durations as the average of existing durations.
const totalDuration = Array.from(timings.values()).reduce(((s, dur) => s + dur), 0);
if (!totalDuration) {
console.warn("No timings; assuming all tests are equally long");
}
const fallbackDuration = totalDuration ? totalDuration / timings.size : 1000;
const groups = Array.from(Array(groupCount), () => []);
const groupDurations = groups.map(() => 0);
// Check for duplicate suite titles.
const suitesByTitle = new Map(suites.map(s => [s.title, s]));
for (const suite of suites) {
if (suitesByTitle.get(suite.title) !== suite) {
assert.fail(`Please fix duplicate suite title: ${suite.title}`);
}
}
// Get timing for the given suite, falling back to fallbackDuration.
function getTiming(suite) {
const value = timings.get(suite.title);
return (typeof value !== 'number' || isNaN(value)) ? fallbackDuration : value;
}
// Sort suites by descending duration.
const sortedSuites = suites.slice().sort((a, b) => getTiming(b) - getTiming(a));
for (const suite of sortedSuites) {
// Pick a least-duration group.
const index = groupDurations.indexOf(Math.min(...groupDurations));
groups[index].push(suite);
groupDurations[index] += getTiming(suite);
}
// Sort each group alphabetically by title.
for (const group of groups) {
group.sort((a, b) => a.title < b.title ? -1 : 1);
}
return groups;
}