core(opportunities): more granular score

lighthouse-cli/test/smokehouse/dobetterweb/dbw-expectations.js

@@ -133,7 +133,7 @@ module.exports = [
         },
       },
       'efficient-animated-content': {
-        score: 0,
+        score: '<0.5',
         details: {
           overallSavingsMs: '>2000',
           items: [

lighthouse-core/audits/byte-efficiency/byte-efficiency-audit.js

@@ -6,6 +6,7 @@
 'use strict';
 
 const Audit = require('../audit');
+const linearInterpolation = require('../../lib/statistics').linearInterpolation;
 const Interactive = require('../../gather/computed/metrics/lantern-interactive'); // eslint-disable-line max-len
 const Simulator = require('../../lib/dependency-graph/simulator/simulator'); // eslint-disable-line no-unused-vars
 const Node = require('../../lib/dependency-graph/node.js'); // eslint-disable-line no-unused-vars
@@ -16,6 +17,7 @@ const KB_IN_BYTES = 1024;
 
 const WASTED_MS_FOR_AVERAGE = 300;
 const WASTED_MS_FOR_POOR = 750;
+const WASTED_MS_FOR_SCORE_OF_ZERO = 5000;
 
 /**
  * @typedef {object} ByteEfficiencyProduct
@@ -32,14 +34,24 @@ const WASTED_MS_FOR_POOR = 750;
  */
 class UnusedBytes extends Audit {
   /**
+   * Creates a score based on the wastedMs value using linear interpolation between control points.
+   *
    * @param {number} wastedMs
    * @return {number}
    */
   static scoreForWastedMs(wastedMs) {
-    if (wastedMs === 0) return 1;
-    else if (wastedMs < WASTED_MS_FOR_AVERAGE) return 0.9;
-    else if (wastedMs < WASTED_MS_FOR_POOR) return 0.65;
-    else return 0;
+    if (wastedMs === 0) {
+      return 1;
+    } else if (wastedMs < WASTED_MS_FOR_AVERAGE) {
+      return linearInterpolation(0, 1, WASTED_MS_FOR_AVERAGE, 0.75, wastedMs);
+    } else if (wastedMs < WASTED_MS_FOR_POOR) {
+      return linearInterpolation(WASTED_MS_FOR_AVERAGE, 0.75, WASTED_MS_FOR_POOR, 0.5, wastedMs);
+    } else {
+      return Math.max(
+        0,
+        linearInterpolation(WASTED_MS_FOR_POOR, 0.5, WASTED_MS_FOR_SCORE_OF_ZERO, 0, wastedMs)
+      );
+    }
   }
 
   /**

lighthouse-core/audits/byte-efficiency/uses-long-cache-ttl.js

@@ -11,6 +11,7 @@ const parseCacheControl = require('parse-cache-control');
 const Audit = require('../audit');
 const WebInspector = require('../../lib/web-inspector');
 const URL = require('../../lib/url-shim');
+const linearInterpolation = require('../../lib/statistics').linearInterpolation;
 
 // Ignore assets that have very high likelihood of cache hit
 const IGNORE_THRESHOLD_IN_PERCENT = 0.925;
@@ -45,20 +46,6 @@ class CacheHeaders extends Audit {
     };
   }
 
-  /**
-   * Interpolates the y value at a point x on the line defined by (x0, y0) and (x1, y1)
-   * @param {number} x0
-   * @param {number} y0
-   * @param {number} x1
-   * @param {number} y1
-   * @param {number} x
-   * @return {number}
-   */
-  static linearInterpolation(x0, y0, x1, y1, x) {
-    const slope = (y1 - y0) / (x1 - x0);
-    return y0 + (x - x0) * slope;
-  }
-
   /**
    * Computes the percent likelihood that a return visit will be within the cache lifetime, based on
    * Chrome UMA stats see the note below.
@@ -90,7 +77,7 @@ class CacheHeaders extends Audit {
     const lowerDecile = (upperDecileIndex - 1) / 10;
 
     // Approximate the real likelihood with linear interpolation
-    return CacheHeaders.linearInterpolation(
+    return linearInterpolation(
       lowerDecileValue,
       lowerDecile,
       upperDecileValue,

lighthouse-core/lib/statistics.js

@@ -59,6 +59,21 @@ function getLogNormalDistribution(median, falloff) {
   };
 }
 
+/**
+ * Interpolates the y value at a point x on the line defined by (x0, y0) and (x1, y1)
+ * @param {number} x0
+ * @param {number} y0
+ * @param {number} x1
+ * @param {number} y1
+ * @param {number} x
+ * @return {number}
+ */
+function linearInterpolation(x0, y0, x1, y1, x) {
+  const slope = (y1 - y0) / (x1 - x0);
+  return y0 + (x - x0) * slope;
+}
+
 module.exports = {
+  linearInterpolation,
   getLogNormalDistribution,
 };

lighthouse-core/test/audits/byte-efficiency/uses-long-cache-ttl-test.js

@@ -39,22 +39,6 @@ describe('Cache headers audit', () => {
     };
   });
 
-  describe('#linearInterpolation', () => {
-    it('correctly interpolates when slope is 2', () => {
-      const slopeOf2 = x => CacheHeadersAudit.linearInterpolation(0, 0, 10, 20, x);
-      assert.equal(slopeOf2(-10), -20);
-      assert.equal(slopeOf2(5), 10);
-      assert.equal(slopeOf2(10), 20);
-    });
-
-    it('correctly interpolates when slope is 0', () => {
-      const slopeOf0 = x => CacheHeadersAudit.linearInterpolation(0, 0, 10, 0, x);
-      assert.equal(slopeOf0(-10), 0);
-      assert.equal(slopeOf0(5), 0);
-      assert.equal(slopeOf0(10), 0);
-    });
-  });
-
   it('detects missing cache headers', () => {
     networkRecords = [networkRecord()];
     return CacheHeadersAudit.audit(artifacts, {options}).then(result => {

lighthouse-core/test/audits/redirects-test.js

@@ -97,7 +97,7 @@ describe('Performance: Redirects audit', () => {
     ]);
 
     return Audit.audit(mockArtifacts(FAILING_TWO_REDIRECTS), {}).then(output => {
-      assert.equal(output.score, 0.65);
+      assert.equal(Math.round(output.score * 100) / 100, 0.56);
       assert.equal(output.details.items.length, 3);
       assert.equal(Math.round(output.rawValue), 638);
     });

lighthouse-core/test/lib/statistics-test.js

@@ -10,28 +10,46 @@
 const assert = require('assert');
 const statistics = require('../../lib/statistics.js');
 
-describe('log normal distribution', () => {
-  it('creates a log normal distribution', () => {
-    // This curve plotted with the below percentile assertions
-    // https://www.desmos.com/calculator/vjk2rwd17y
+describe('statistics', () => {
+  describe('#getLogNormalDistribution', () => {
+    it('creates a log normal distribution', () => {
+      // This curve plotted with the below percentile assertions
+      // https://www.desmos.com/calculator/vjk2rwd17y
 
-    const median = 5000;
-    const pODM = 3500;
-    const distribution = statistics.getLogNormalDistribution(median, pODM);
+      const median = 5000;
+      const pODM = 3500;
+      const distribution = statistics.getLogNormalDistribution(median, pODM);
 
-    function getPct(distribution, value) {
-      return Number(distribution.computeComplementaryPercentile(value).toFixed(2));
-    }
-    assert.equal(typeof distribution.computeComplementaryPercentile, 'function');
-    assert.equal(getPct(distribution, 2000), 1.00, 'pct for 2000 does not match');
-    assert.equal(getPct(distribution, 3000), 0.98, 'pct for 3000 does not match');
-    assert.equal(getPct(distribution, 3500), 0.92, 'pct for 3500 does not match');
-    assert.equal(getPct(distribution, 4000), 0.81, 'pct for 4000 does not match');
-    assert.equal(getPct(distribution, 5000), 0.50, 'pct for 5000 does not match');
-    assert.equal(getPct(distribution, 6000), 0.24, 'pct for 6000 does not match');
-    assert.equal(getPct(distribution, 7000), 0.09, 'pct for 7000 does not match');
-    assert.equal(getPct(distribution, 8000), 0.03, 'pct for 8000 does not match');
-    assert.equal(getPct(distribution, 9000), 0.01, 'pct for 9000 does not match');
-    assert.equal(getPct(distribution, 10000), 0.00, 'pct for 10000 does not match');
+      function getPct(distribution, value) {
+        return Number(distribution.computeComplementaryPercentile(value).toFixed(2));
+      }
+      assert.equal(typeof distribution.computeComplementaryPercentile, 'function');
+      assert.equal(getPct(distribution, 2000), 1.00, 'pct for 2000 does not match');
+      assert.equal(getPct(distribution, 3000), 0.98, 'pct for 3000 does not match');
+      assert.equal(getPct(distribution, 3500), 0.92, 'pct for 3500 does not match');
+      assert.equal(getPct(distribution, 4000), 0.81, 'pct for 4000 does not match');
+      assert.equal(getPct(distribution, 5000), 0.50, 'pct for 5000 does not match');
+      assert.equal(getPct(distribution, 6000), 0.24, 'pct for 6000 does not match');
+      assert.equal(getPct(distribution, 7000), 0.09, 'pct for 7000 does not match');
+      assert.equal(getPct(distribution, 8000), 0.03, 'pct for 8000 does not match');
+      assert.equal(getPct(distribution, 9000), 0.01, 'pct for 9000 does not match');
+      assert.equal(getPct(distribution, 10000), 0.00, 'pct for 10000 does not match');
+    });
+  });
+
+  describe('#linearInterpolation', () => {
+    it('correctly interpolates when slope is 2', () => {
+      const slopeOf2 = x => statistics.linearInterpolation(0, 0, 10, 20, x);
+      assert.equal(slopeOf2(-10), -20);
+      assert.equal(slopeOf2(5), 10);
+      assert.equal(slopeOf2(10), 20);
+    });
+
+    it('correctly interpolates when slope is 0', () => {
+      const slopeOf0 = x => statistics.linearInterpolation(0, 0, 10, 0, x);
+      assert.equal(slopeOf0(-10), 0);
+      assert.equal(slopeOf0(5), 0);
+      assert.equal(slopeOf0(10), 0);
+    });
   });
 });

lighthouse-core/test/results/sample_v2.json

@@ -1869,7 +1869,7 @@
       "id": "render-blocking-resources",
       "title": "Eliminate render-blocking resources",
       "description": "Resources are blocking the first paint of your page. Consider delivering critical JS/CSS inline and deferring all non-critical JS/styles. [Learn more](https://developers.google.com/web/tools/lighthouse/audits/blocking-resources).",
-      "score": 0,
+      "score": 0.46,
       "scoreDisplayMode": "numeric",
       "rawValue": 1129,
       "displayValue": "5 resources delayed first paint by 1129ms",
@@ -2067,7 +2067,7 @@
       "id": "uses-text-compression",
       "title": "Enable text compression",
       "description": "Text-based responses should be served with compression (gzip, deflate or brotli) to minimize total network bytes. [Learn more](https://developers.google.com/web/fundamentals/performance/optimizing-content-efficiency/optimize-encoding-and-transfer).",
-      "score": 0.9,
+      "score": 0.88,
       "scoreDisplayMode": "numeric",
       "rawValue": 150,
       "displayValue": [