add test

lighthouse-core/computed/metrics/lantern-max-potential-fid.js

@@ -13,10 +13,6 @@ const LanternFirstContentfulPaint = require('./lantern-first-contentful-paint.js
 /** @typedef {BaseNode.Node} Node */
 
 class LanternMaxPotentialFID extends LanternMetricArtifact {
-  get name() {
-    return 'LanternMaxPotentialFID';
-  }
-
   /**
    * @return {LH.Gatherer.Simulation.MetricCoefficients}
    */

lighthouse-core/computed/metrics/max-potential-fid.js

@@ -25,7 +25,7 @@ class MaxPotentialFID extends MetricArtifact {
    * @param {LH.Artifacts.MetricComputationData} data
    * @return {Promise<LH.Artifacts.Metric>}
    */
-  computeObservedMetric(data) {
+  static computeObservedMetric(data) {
     const {firstContentfulPaint} = data.traceOfTab.timings;
     if (!firstContentfulPaint) {
       throw new LHError(LHError.errors.NO_FCP);

lighthouse-core/test/computed/metrics/__snapshots__/max-potential-fid-test.js.snap

@@ -0,0 +1,9 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Metrics: Max Potential FID should compute a simulated value 1`] = `
+Object {
+  "optimistic": 396,
+  "pessimistic": 396,
+  "timing": 396,
+}
+`;

lighthouse-core/test/computed/metrics/max-potential-fid-test.js

@@ -0,0 +1,36 @@
+/**
+ * @license Copyright 2018 Google Inc. 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 assert = require('assert');
+
+const MaxPotentialFID = require('../../../computed/metrics/max-potential-fid.js');
+const trace = require('../../fixtures/traces/progressive-app-m60.json');
+const devtoolsLog = require('../../fixtures/traces/progressive-app-m60.devtools.log.json');
+
+/* eslint-env jest */
+
+describe('Metrics: Max Potential FID', () => {
+  it('should compute a simulated value', async () => {
+    const settings = {throttlingMethod: 'simulate'};
+    const context = {settings, computedCache: new Map()};
+    const result = await MaxPotentialFID.request({trace, devtoolsLog, settings}, context);
+
+    expect({
+      timing: Math.round(result.timing),
+      optimistic: Math.round(result.optimisticEstimate.timeInMs),
+      pessimistic: Math.round(result.pessimisticEstimate.timeInMs),
+    }).toMatchSnapshot();
+  });
+
+  it('should compute an observed value', async () => {
+    const settings = {throttlingMethod: 'provided'};
+    const context = {settings, computedCache: new Map()};
+    const result = await MaxPotentialFID.request({trace, devtoolsLog, settings}, context);
+
+    assert.equal(Math.round(result.timing), 198);
+  });
+});