core: centralize error strings

lighthouse-cli/run.js

@@ -13,10 +13,10 @@ const Printer = require('./printer');
 const ChromeLauncher = require('chrome-launcher');
 
 const yargsParser = require('yargs-parser');
-const lighthouse = require('../lighthouse-core/index.js');
+const lighthouse = require('../lighthouse-core');
 const log = require('lighthouse-logger');
-const getFilenamePrefix = require('../lighthouse-core/lib/file-namer.js').getFilenamePrefix;
-const assetSaver = require('../lighthouse-core/lib/asset-saver.js');
+const getFilenamePrefix = require('../lighthouse-core/lib/file-namer').getFilenamePrefix;
+const assetSaver = require('../lighthouse-core/lib/asset-saver');
 
 const opn = require('opn');
 
@@ -65,34 +65,27 @@ function showConnectionError() {
   process.exit(_RUNTIME_ERROR_CODE);
 }
 
+function showProtocolTimeoutError() {
+  console.error('Debugger protocol timed out while connecting to Chrome.');
+  process.exit(_PROTOCOL_TIMEOUT_EXIT_CODE);
+}
+
 /**
  * @param {!LH.LighthouseError} err
  */
 function showRuntimeError(err) {
-  console.error('Runtime error encountered:', err);
+  console.error('Runtime error encountered:', err.friendlyMessage || err.message);
   if (err.stack) {
     console.error(err.stack);
   }
   process.exit(_RUNTIME_ERROR_CODE);
 }
 
-function showProtocolTimeoutError() {
-  console.error('Debugger protocol timed out while connecting to Chrome.');
-  process.exit(_PROTOCOL_TIMEOUT_EXIT_CODE);
-}
-
-function showPageLoadError() {
-  console.error('Unable to load the page. Please verify the url you are trying to review.');
-  process.exit(_RUNTIME_ERROR_CODE);
-}
-
 /**
  * @param {!LH.LighthouseError} err
  */
 function handleError(err) {
-  if (err.code === 'PAGE_LOAD_ERROR') {
-    showPageLoadError();
-  } else if (err.code === 'ECONNREFUSED') {
+  if (err.code === 'ECONNREFUSED') {
     showConnectionError();
   } else if (err.code === 'CRI_TIMEOUT') {
     showProtocolTimeoutError();

lighthouse-core/audits/byte-efficiency/unminified-javascript.js

@@ -30,7 +30,7 @@ class UnminifiedJavaScript extends ByteEfficiencyAudit {
       name: 'unminified-javascript',
       description: 'Minify JavaScript',
       informative: true,
-      helpText: 'Minifying JavaScript files can reduce payload sizes and script parse time.' +
+      helpText: 'Minifying JavaScript files can reduce payload sizes and script parse time. ' +
         '[Learn more](https://developers.google.com/speed/docs/insights/MinifyResources).',
       requiredArtifacts: ['Scripts', 'devtoolsLogs'],
     };

lighthouse-core/audits/consistently-interactive.js

@@ -6,9 +6,10 @@
 'use strict';
 
 const Audit = require('./audit');
-const Util = require('../report/v2/renderer/util.js');
+const Util = require('../report/v2/renderer/util');
 const NetworkRecorder = require('../lib/network-recorder');
 const TracingProcessor = require('../lib/traces/tracing-processor');
+const LHError = require('../lib/errors');
 
 // Parameters (in ms) for log-normal CDF scoring. To see the curve:
 //   https://www.desmos.com/calculator/uti67afozh
@@ -145,10 +146,11 @@ class ConsistentlyInteractiveMetric extends Audit {
       }
     }
 
-    const culprit = cpuCandidate ? 'Network' : 'Main thread';
-    throw new Error(`${culprit} activity continued through the end of the trace recording. ` +
-      'Consistently Interactive requires a minimum of 5 seconds of both main thread idle and ' +
-      'network idle.');
+    throw new LHError(
+      cpuCandidate
+        ? LHError.errors.NO_TTI_NETWORK_IDLE_PERIOD
+        : LHError.errors.NO_TTI_CPU_IDLE_PERIOD
+    );
   }
 
   /**
@@ -166,11 +168,11 @@ class ConsistentlyInteractiveMetric extends Audit {
     return Promise.all(computedArtifacts)
       .then(([networkRecords, traceOfTab]) => {
         if (!traceOfTab.timestamps.firstMeaningfulPaint) {
-          throw new Error('No firstMeaningfulPaint found in trace.');
+          throw new LHError(LHError.errors.NO_FMP);
         }
 
         if (!traceOfTab.timestamps.domContentLoaded) {
-          throw new Error('No domContentLoaded found in trace.');
+          throw new LHError(LHError.errors.NO_DCL);
         }
 
         const longTasks = TracingProcessor.getMainThreadTopLevelEvents(traceOfTab)

lighthouse-core/audits/estimated-input-latency.js

@@ -6,8 +6,9 @@
 'use strict';
 
 const Audit = require('./audit');
-const Util = require('../report/v2/renderer/util.js');
+const Util = require('../report/v2/renderer/util');
 const TracingProcessor = require('../lib/traces/tracing-processor');
+const LHError = require('../lib/errors');
 
 // Parameters (in ms) for log-normal CDF scoring. To see the curve:
 // https://www.desmos.com/calculator/srv0hqhf7d
@@ -35,7 +36,7 @@ class EstimatedInputLatency extends Audit {
   static calculate(tabTrace) {
     const startTime = tabTrace.timings.firstMeaningfulPaint;
     if (!startTime) {
-      throw new Error('No firstMeaningfulPaint event found in trace');
+      throw new LHError(LHError.errors.NO_FMP);
     }
 
     const latencyPercentiles = TracingProcessor.getRiskToResponsiveness(tabTrace, startTime);

lighthouse-core/audits/first-meaningful-paint.js

@@ -6,7 +6,8 @@
 'use strict';
 
 const Audit = require('./audit');
-const Util = require('../report/v2/renderer/util.js');
+const Util = require('../report/v2/renderer/util');
+const LHError = require('../lib/errors');
 
 // Parameters (in ms) for log-normal CDF scoring. To see the curve:
 // https://www.desmos.com/calculator/joz3pqttdq
@@ -40,13 +41,13 @@ class FirstMeaningfulPaint extends Audit {
     const trace = artifacts.traces[this.DEFAULT_PASS];
     return artifacts.requestTraceOfTab(trace).then(tabTrace => {
       if (!tabTrace.firstMeaningfulPaintEvt) {
-        throw new Error('No usable `firstMeaningfulPaint(Candidate)` events found in trace');
+        throw new LHError(LHError.errors.NO_FMP);
       }
 
       // navigationStart is currently essential to FMP calculation.
       // see: https://github.com/GoogleChrome/lighthouse/issues/753
       if (!tabTrace.navigationStartEvt) {
-        throw new Error('No `navigationStart` event found in trace');
+        throw new LHError(LHError.errors.NO_NAVSTART);
       }
 
       const result = this.calculateScore(tabTrace);

lighthouse-core/audits/speed-index-metric.js

@@ -7,6 +7,7 @@
 
 const Audit = require('./audit');
 const Util = require('../report/v2/renderer/util');
+const LHError = require('../lib/errors');
 
 // Parameters (in ms) for log-normal CDF scoring. To see the curve:
 // https://www.desmos.com/calculator/mdgjzchijg
@@ -40,11 +41,11 @@ class SpeedIndexMetric extends Audit {
     // run speedline
     return artifacts.requestSpeedline(trace).then(speedline => {
       if (speedline.frames.length === 0) {
-        throw new Error('Trace unable to find visual progress frames.');
+        throw new LHError(LHError.errors.NO_SPEEDLINE_FRAMES);
       }
 
       if (speedline.perceptualSpeedIndex === 0) {
-        throw new Error('Error in Speedline calculating Speed Index (speedIndex of 0).');
+        throw new LHError(LHError.errors.SPEEDINDEX_OF_ZERO);
       }
 
       let visuallyReadyInMs = undefined;

lighthouse-core/gather/computed/first-interactive.js

@@ -7,6 +7,7 @@
 
 const ComputedArtifact = require('./computed-artifact');
 const TracingProcessor = require('../../lib/traces/tracing-processor');
+const LHError = require('../../lib/errors');
 
 const LONG_TASK_THRESHOLD = 50;
 
@@ -15,8 +16,6 @@ const MIN_TASK_CLUSTER_PADDING = 1000;
 const MIN_TASK_CLUSTER_FMP_DISTANCE = 5000;
 
 const MAX_QUIET_WINDOW_SIZE = 5000;
-const TRACE_BUSY_MSG = 'The main thread was busy for the entire trace recording. ' +
-   'First Interactive requires the main thread to be idle for several seconds.';
 
 // Window size should be three seconds at 15 seconds after FMP
 const EXPONENTIATION_COEFFICIENT = -Math.log(3 - 1) / 15;
@@ -143,7 +142,7 @@ class FirstInteractive extends ComputedArtifact {
 
       // Check that we have a long enough trace
       if (windowEnd > traceEnd) {
-        throw new Error(TRACE_BUSY_MSG);
+        throw new LHError(LHError.errors.NO_FCPUI_IDLE_PERIOD);
       }
 
       // Check that this task isn't the beginning of a cluster
@@ -160,7 +159,7 @@ class FirstInteractive extends ComputedArtifact {
       }
     }
 
-    throw new Error(TRACE_BUSY_MSG);
+    throw new LHError(LHError.errors.NO_FCPUI_IDLE_PERIOD);
   }
 
   /**
@@ -174,11 +173,11 @@ class FirstInteractive extends ComputedArtifact {
     const traceEnd = traceOfTab.timings.traceEnd;
 
     if (traceEnd - FMP < MAX_QUIET_WINDOW_SIZE) {
-      throw new Error('trace not at least 5 seconds longer than FMP');
+      throw new LHError(LHError.errors.FMP_TOO_LATE_FOR_FCPUI);
     }
 
     if (!FMP || !DCL) {
-      throw new Error(`No ${FMP ? 'domContentLoaded' : 'firstMeaningfulPaint'} event in trace`);
+      throw new LHError(FMP ? LHError.errors.NO_DCL : LHError.errors.NO_FMP);
     }
 
     const longTasksAfterFMP = TracingProcessor.getMainThreadTopLevelEvents(traceOfTab, FMP)

lighthouse-core/gather/computed/speedline.js

@@ -7,6 +7,7 @@
 
 const ComputedArtifact = require('./computed-artifact');
 const speedline = require('speedline');
+const LHError = require('../../lib/errors');
 
 class Speedline extends ComputedArtifact {
   get name() {
@@ -31,6 +32,12 @@ class Speedline extends ComputedArtifact {
         fastMode: true,
         include: 'perceptualSpeedIndex',
       });
+    }).catch(err => {
+      if (/No screenshots found in trace/.test(err.message)) {
+        throw new LHError(LHError.errors.NO_SCREENSHOTS);
+      }
+
+      throw err;
     });
   }
 }

lighthouse-core/gather/computed/trace-of-tab.js

@@ -18,6 +18,7 @@
 
 const ComputedArtifact = require('./computed-artifact');
 const log = require('lighthouse-logger');
+const LHError = require('../../lib/errors');
 const Sentry = require('../../lib/sentry');
 
 // Bring in web-inspector for side effect of adding [].stableSort
@@ -51,13 +52,13 @@ class TraceOfTab extends ComputedArtifact {
     // The first TracingStartedInPage in the trace is definitely our renderer thread of interest
     // Beware: the tracingStartedInPage event can appear slightly after a navigationStart
     const startedInPageEvt = keyEvents.find(e => e.name === 'TracingStartedInPage');
-    if (!startedInPageEvt) throw new Error('TracingStartedInPage was not found in the trace');
+    if (!startedInPageEvt) throw new LHError(LHError.errors.NO_TRACING_STARTED);
     // Filter to just events matching the frame ID for sanity
     const frameEvents = keyEvents.filter(e => e.args.frame === startedInPageEvt.args.data.page);
 
     // Our navStart will be the last frame navigation in the trace
     const navigationStart = frameEvents.filter(e => e.name === 'navigationStart').pop();
-    if (!navigationStart) throw new Error('navigationStart was not found in the trace');
+    if (!navigationStart) throw new LHError(LHError.errors.NO_NAVSTART);
 
     // Find our first paint of this frame
     const firstPaint = frameEvents.find(e => e.name === 'firstPaint' && e.ts > navigationStart.ts);

lighthouse-core/gather/connections/connection.js

@@ -8,6 +8,7 @@
 
 const EventEmitter = require('events').EventEmitter;
 const log = require('lighthouse-logger');
+const LHError = require('../../lib/errors');
 
 class Connection {
   constructor() {
@@ -99,12 +100,7 @@ class Connection {
         if (object.error) {
           const logLevel = callback.options && callback.options.silent ? 'verbose' : 'error';
           log.formatProtocol('method <= browser ERR', {method: callback.method}, logLevel);
-          let errMsg = `(${callback.method}): ${object.error.message}`;
-          if (object.error.data) errMsg += ` (${object.error.data})`;
-          const error = new Error(`Protocol error ${errMsg}`);
-          error.protocolMethod = callback.method;
-          error.protocolError = object.error.message;
-          throw error;
+          throw LHError.fromProtocolMessage(callback.method, object.error);
         }
 
         log.formatProtocol('method <= browser OK',

lighthouse-core/gather/connections/cri.js

@@ -114,6 +114,7 @@ class CriConnection extends Connection {
           }
         });
 
+        // TODO: Replace this with an LHError on next major version bump
         // Reject on error with code specifically indicating timeout in connection setup.
         const err = new Error('Timeout waiting for initial Debugger Protocol connection.');
         err.code = 'CRI_TIMEOUT';

lighthouse-core/gather/gather-runner.js

@@ -8,6 +8,7 @@
 
 const log = require('lighthouse-logger');
 const Audit = require('../audits/audit');
+const LHError = require('../lib/errors');
 const URL = require('../lib/url-shim');
 const NetworkRecorder = require('../lib/network-recorder.js');
 
@@ -149,17 +150,18 @@ class GatherRunner {
       return URL.equalWithExcludedFragments(record.url, url);
     });
 
-    let errorMessage;
+    let errorCode;
+    let errorReason;
     if (!mainRecord) {
-      errorMessage = 'no document request found';
+      errorCode = LHError.errors.NO_DOCUMENT_REQUEST;
     } else if (mainRecord.failed) {
-      errorMessage = `failed document request (${mainRecord.localizedFailDescription})`;
+      errorCode = LHError.errors.FAILED_DOCUMENT_REQUEST;
+      errorReason = mainRecord.localizedFailDescription;
     }
 
-    if (errorMessage) {
-      log.error('GatherRunner', errorMessage, url);
-      const error = new Error(`Unable to load page: ${errorMessage}`);
-      error.code = 'PAGE_LOAD_ERROR';
+    if (errorCode) {
+      const error = new LHError(errorCode, {reason: errorReason});
+      log.error('GatherRunner', error.message, url);
       return error;
     }
   }
@@ -355,7 +357,7 @@ class GatherRunner {
           // runner to handle turning it into an error audit.
           artifacts[gathererName] = err;
           // Track page load errors separately, so we can fail loudly if needed.
-          if (err.code === 'PAGE_LOAD_ERROR') pageLoadFailures.push(err);
+          if (LHError.isPageLoadError(err)) pageLoadFailures.push(err);
         });
       });
     }, Promise.resolve()).then(_ => {