byte-efficiency-audit-test.js

/**
 * @license Copyright 2017 The Lighthouse Authors. All Rights Reserved.
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
 */
'use strict';

const ByteEfficiencyAudit_ = require('../../../audits/byte-efficiency/byte-efficiency-audit.js');
const NetworkNode = require('../../../lib/dependency-graph/network-node.js');
const CPUNode = require('../../../lib/dependency-graph/cpu-node.js');
const Simulator = require('../../../lib/dependency-graph/simulator/simulator.js');
const PageDependencyGraph = require('../../../computed/page-dependency-graph.js');
const LoadSimulator = require('../../../computed/load-simulator.js');


const trace = require('../../fixtures/traces/progressive-app-m60.json');
const devtoolsLog = require('../../fixtures/traces/progressive-app-m60.devtools.log.json');
const assert = require('assert').strict;

/* eslint-env jest */

describe('Byte efficiency base audit', () => {
  let graph;
  let simulator;

  const ByteEfficiencyAudit = class extends ByteEfficiencyAudit_ {
    static get meta() {
      return {name: 'test'};
    }
  };

  beforeEach(() => {
    const networkRecord = {
      requestId: 1,
      url: 'http://example.com/',
      parsedURL: {scheme: 'http', securityOrigin: 'http://example.com'},
      transferSize: 400000,
      timing: {receiveHeadersEnd: 0},
    };

    graph = new NetworkNode(networkRecord);
    // add a CPU node to force improvement to TTI
    graph.addDependent(new CPUNode({tid: 1, ts: 0, dur: 100 * 1000}));
    simulator = new Simulator({});
  });

  const baseHeadings = [
    {key: 'totalBytes', itemType: 'bytes', displayUnit: 'kb', granularity: 1, text: ''},
    {key: 'wastedBytes', itemType: 'bytes', displayUnit: 'kb', granularity: 1, text: ''},
    {key: 'wastedMs', itemType: 'text', text: ''},
  ];

  describe('#estimateTransferSize', () => {
    const estimate = ByteEfficiencyAudit.estimateTransferSize;

    it('should estimate by resource type compression ratio when no network info available', () => {
      assert.equal(estimate(undefined, 1000, 'Stylesheet'), 200);
      assert.equal(estimate(undefined, 1000, 'Script'), 330);
      assert.equal(estimate(undefined, 1000, 'Document'), 330);
      assert.equal(estimate(undefined, 1000, ''), 500);
    });

    it('should return transferSize when asset matches', () => {
      const resourceType = 'Stylesheet';
      const result = estimate({transferSize: 1234, resourceType}, 10000, 'Stylesheet');
      assert.equal(result, 1234);
    });

    it('should estimate by network compression ratio when asset does not match', () => {
      const resourceType = 'Other';
      const result = estimate({resourceSize: 2000, transferSize: 1000, resourceType}, 100);
      assert.equal(result, 50);
    });

    it('should not error when missing resource size', () => {
      const resourceType = 'Other';
      const result = estimate({transferSize: 1000, resourceType}, 100);
      assert.equal(result, 100);
    });

    it('should not error when resource size is 0', () => {
      const resourceType = 'Other';
      const result = estimate({transferSize: 1000, resourceSize: 0, resourceType}, 100);
      assert.equal(result, 100);
    });
  });

  it('should format details', () => {
    const result = ByteEfficiencyAudit.createAuditProduct({
      headings: baseHeadings,
      items: [],
    }, graph, simulator);

    assert.deepEqual(result.details.items, []);
  });

  it('should set the numericValue', () => {
    const result = ByteEfficiencyAudit.createAuditProduct(
      {
        headings: baseHeadings,
        items: [
          {url: 'http://example.com/', wastedBytes: 200 * 1000},
        ],
      },
      graph,
      simulator
    );

    // 900ms savings comes from the graph calculation
    assert.equal(result.numericValue, 900);
  });

  it('should score the wastedMs', () => {
    const perfectResult = ByteEfficiencyAudit.createAuditProduct({
      headings: baseHeadings,
      items: [{url: 'http://example.com/', wastedBytes: 1 * 1000}],
    }, graph, simulator);

    const goodResult = ByteEfficiencyAudit.createAuditProduct({
      headings: baseHeadings,
      items: [{url: 'http://example.com/', wastedBytes: 20 * 1000}],
    }, graph, simulator);

    const averageResult = ByteEfficiencyAudit.createAuditProduct({
      headings: baseHeadings,
      items: [{url: 'http://example.com/', wastedBytes: 100 * 1000}],
    }, graph, simulator);

    const failingResult = ByteEfficiencyAudit.createAuditProduct({
      headings: baseHeadings,
      items: [{url: 'http://example.com/', wastedBytes: 400 * 1000}],
    }, graph, simulator);

    assert.equal(perfectResult.score, 1, 'scores perfect wastedMs');
    assert.ok(goodResult.score > 0.75 && goodResult.score < 1, 'scores good wastedMs');
    assert.ok(averageResult.score > 0.5 && averageResult.score < 0.75, 'scores average wastedMs');
    assert.ok(failingResult.score < 0.5, 'scores failing wastedMs');
  });

  it('should throw on invalid graph', () => {
    assert.throws(() => {
      ByteEfficiencyAudit.createAuditProduct({
        headings: baseHeadings,
        items: [{wastedBytes: 350, totalBytes: 700, wastedPercent: 50}],
      }, null);
    });
  });

  it('should populate KiB', () => {
    const result = ByteEfficiencyAudit.createAuditProduct({
      headings: baseHeadings,
      items: [
        {wastedBytes: 2048, totalBytes: 4096, wastedPercent: 50},
        {wastedBytes: 1986, totalBytes: 5436},
      ],
    }, graph, simulator);

    assert.equal(result.details.items[0].wastedBytes, 2048);
    assert.equal(result.details.items[0].totalBytes, 4096);
    assert.equal(result.details.items[1].wastedBytes, 1986);
    assert.equal(result.details.items[1].totalBytes, 5436);
  });

  it('should sort on wastedBytes', () => {
    const result = ByteEfficiencyAudit.createAuditProduct({
      headings: baseHeadings,
      items: [
        {wastedBytes: 350, totalBytes: 700, wastedPercent: 50},
        {wastedBytes: 450, totalBytes: 1000, wastedPercent: 50},
        {wastedBytes: 400, totalBytes: 450, wastedPercent: 50},
      ],
    }, graph, simulator);

    assert.equal(result.details.items[0].wastedBytes, 450);
    assert.equal(result.details.items[1].wastedBytes, 400);
    assert.equal(result.details.items[2].wastedBytes, 350);
  });

  it('should create a display value', () => {
    const result = ByteEfficiencyAudit.createAuditProduct({
      headings: baseHeadings,
      items: [
        {wastedBytes: 512, totalBytes: 700, wastedPercent: 50},
        {wastedBytes: 512, totalBytes: 1000, wastedPercent: 50},
        {wastedBytes: 1024, totalBytes: 1200, wastedPercent: 50},
      ],
    }, graph, simulator);

    expect(result.displayValue).toBeDisplayString(/savings of 2/);
  });

  it('should work on real graphs', async () => {
    const throttling = {rttMs: 150, throughputKbps: 1600, cpuSlowdownMultiplier: 1};
    const settings = {throttlingMethod: 'simulate', throttling};
    const computedCache = new Map();
    const graph = await PageDependencyGraph.request({trace, devtoolsLog}, {computedCache});
    const simulator = await LoadSimulator.request({devtoolsLog, settings}, {computedCache});
    const result = ByteEfficiencyAudit.createAuditProduct(
      {
        headings: [{key: 'value', text: 'Label'}],
        items: [
          {url: 'https://www.googletagmanager.com/gtm.js?id=GTM-Q5SW', wastedBytes: 30 * 1024},
        ],
      },
      graph,
      simulator
    );

    assert.equal(result.numericValue, 300);
  });

  it('should create load simulator with the specified settings', async () => {
    class MockAudit extends ByteEfficiencyAudit {
      static audit_(artifacts, records) {
        return {
          items: records.map(record => ({url: record.url, wastedBytes: record.transferSize})),
          headings: [],
        };
      }
    }

    const artifacts = {
      traces: {defaultPass: trace},
      devtoolsLogs: {defaultPass: devtoolsLog},
    };
    const computedCache = new Map();

    const modestThrottling = {rttMs: 150, throughputKbps: 1000, cpuSlowdownMultiplier: 2};
    const ultraSlowThrottling = {rttMs: 150, throughputKbps: 100, cpuSlowdownMultiplier: 8};
    let settings = {throttlingMethod: 'simulate', throttling: modestThrottling};
    let result = await MockAudit.audit(artifacts, {settings, computedCache});
    // expect modest savings
    expect(result.numericValue).toBeLessThan(5000);
    expect(result.numericValue).toMatchSnapshot();

    settings = {throttlingMethod: 'simulate', throttling: ultraSlowThrottling};
    result = await MockAudit.audit(artifacts, {settings, computedCache});
    // expect lots of savings
    expect(result.numericValue).not.toBeLessThan(5000);
    expect(result.numericValue).toMatchSnapshot();
  });

  it('should allow overriding of computeWasteWithTTIGraph', async () => {
    class MockAudit extends ByteEfficiencyAudit {
      static audit_(artifacts, records) {
        return {
          items: records.map(record => ({url: record.url, wastedBytes: record.transferSize})),
          headings: [],
        };
      }
    }

    class MockJustTTIAudit extends MockAudit {
      static computeWasteWithTTIGraph(results, graph, simulator) {
        return ByteEfficiencyAudit.computeWasteWithTTIGraph(results, graph, simulator,
          {includeLoad: false});
      }
    }

    const artifacts = {
      traces: {defaultPass: trace},
      devtoolsLogs: {defaultPass: devtoolsLog},
    };
    const computedCache = new Map();

    const modestThrottling = {rttMs: 150, throughputKbps: 1000, cpuSlowdownMultiplier: 2};
    const settings = {throttlingMethod: 'simulate', throttling: modestThrottling};
    const result = await MockAudit.audit(artifacts, {settings, computedCache});
    const resultTti = await MockJustTTIAudit.audit(artifacts, {settings, computedCache});
    // expect less savings with just TTI
    expect(resultTti.numericValue).toBeLessThan(result.numericValue);
    expect({default: result.numericValue, justTTI: resultTti.numericValue}).toMatchSnapshot();
  });
});