core: append sourceURL comment to eval code (#13754)

connorjclark · web-flow · commit 6b2d0f04b716 · 2022-03-30T16:41:40.000-07:00
diff --git a/lighthouse-core/gather/driver/execution-context.js b/lighthouse-core/gather/driver/execution-context.js
@@ -97,7 +97,8 @@ class ExecutionContext {
             .catch(${pageFunctions.wrapRuntimeEvalErrorInBrowserString})
             .then(resolve);
         });
-      }())`,
+      }())
+      //# sourceURL=_lighthouse-eval.js`,
       includeCommandLineAPI: true,
       awaitPromise: true,
       returnByValue: true,
@@ -195,7 +196,8 @@ class ExecutionContext {
       ${ExecutionContext._cachedNativesPreamble};
       ${depsSerialized};
       (${mainFn})(${argsSerialized});
-    })()`;
+    })()
+    //# sourceURL=_lighthouse-eval.js`;
 
     await this._session.sendCommand('Page.addScriptToEvaluateOnNewDocument', {source: expression});
   }
diff --git a/lighthouse-core/gather/gatherers/js-usage.js b/lighthouse-core/gather/gatherers/js-usage.js
@@ -50,12 +50,13 @@ class JsUsage extends FRGatherer {
     const usageByScriptId = {};
 
     for (const scriptUsage of this._scriptUsages) {
-      // If `url` is blank, that means the script was anonymous (eval, new Function, onload, ...).
-      // Or, it's because it was code Lighthouse over the protocol via `Runtime.evaluate`.
-      // We currently don't consider coverage of anonymous scripts, and we definitely don't want
-      // coverage of code Lighthouse ran to inspect the page, so we ignore this ScriptCoverage if
-      // url is blank.
-      if (scriptUsage.url === '') {
+      // If `url` is blank, that means the script was dynamically
+      // created (eval, new Function, onload, ...)
+      if (scriptUsage.url === '' || scriptUsage.url === '_lighthouse-eval.js') {
+        // We currently don't consider coverage of dynamic scripts, and we definitely don't want
+        // coverage of code Lighthouse ran to inspect the page, so we ignore this ScriptCoverage.
+        // Audits would work the same without this, it is only an optimization (not tracking coverage
+        // for scripts we don't care about).
         continue;
       }
 
diff --git a/lighthouse-core/gather/gatherers/scripts.js b/lighthouse-core/gather/gatherers/scripts.js
@@ -28,6 +28,23 @@ async function runInSeriesOrParallel(values, promiseMapper, runInSeries) {
   }
 }
 
+/**
+ * Returns true if the script was created via our own calls
+ * to Runtime.evaluate.
+ * @param {LH.Crdp.Debugger.ScriptParsedEvent} script
+ */
+function isLighthouseRuntimeEvaluateScript(script) {
+  // Scripts created by Runtime.evaluate that run on the main session/frame
+  // result in an empty string for the embedderName.
+  // Or, it means the script was dynamically created (eval, new Function, onload, ...)
+  if (!script.embedderName) return true;
+
+  // Otherwise, when running our own code inside other frames, the embedderName
+  // is set to the frame's url. In that case, we rely on the special sourceURL that
+  // we set.
+  return script.hasSourceURL && script.url === '_lighthouse-eval.js';
+}
+
 /**
  * @fileoverview Gets JavaScript file contents.
  */
@@ -68,8 +85,9 @@ class Scripts extends FRGatherer {
     // it also blocks scripts from the same origin but that happen to run in a different process,
     // like a worker.
     if (event.method === 'Debugger.scriptParsed' && !sessionId) {
-      // Events without an embedderName (read: a url) are for JS that we ran over the protocol.
-      if (event.params.embedderName) this._scriptParsedEvents.push(event.params);
+      if (!isLighthouseRuntimeEvaluateScript(event.params)) {
+        this._scriptParsedEvents.push(event.params);
+      }
     }
   }
 
diff --git a/lighthouse-core/test/gather/driver/execution-context-test.js b/lighthouse-core/test/gather/driver/execution-context-test.js
@@ -241,7 +241,8 @@ const fetch = globalThis.__nativeFetch || globalThis.fetch;
 })
             .then(resolve);
         });
-      }())`.trim();
+      }())
+      //# sourceURL=_lighthouse-eval.js`.trim();
     expect(trimTrailingWhitespace(expression)).toBe(trimTrailingWhitespace(expected));
     expect(await eval(expression)).toBe(1);
   });
