misc(runner): add assertion for devtoolsLog as requiredArtifact

lighthouse-core/runner.js

@@ -289,11 +289,13 @@ class Runner {
       for (const artifactName of audit.meta.requiredArtifacts) {
         const noArtifact = artifacts[artifactName] === undefined;
 
-        // If trace required, check that DEFAULT_PASS trace exists.
-        // TODO: need pass-specific check of networkRecords and traces.
-        const noTrace = artifactName === 'traces' && !artifacts.traces[Audit.DEFAULT_PASS];
+        // If trace/devtoolsLog required, check that DEFAULT_PASS trace/devtoolsLog exists.
+        // NOTE: for now, not a pass-specific check of traces or devtoolsLogs.
+        const noRequiredTrace = artifactName === 'traces' && !artifacts.traces[Audit.DEFAULT_PASS];
+        const noRequiredDevtoolsLog = artifactName === 'devtoolsLogs' &&
+            !artifacts.devtoolsLogs[Audit.DEFAULT_PASS];
 
-        if (noArtifact || noTrace) {
+        if (noArtifact || noRequiredTrace || noRequiredDevtoolsLog) {
           log.warn('Runner',
               `${artifactName} gatherer, required by audit ${audit.meta.id}, did not run.`);
           throw new Error(`Required ${artifactName} gatherer did not run.`);

lighthouse-core/test/runner-test.js

@@ -293,6 +293,24 @@ describe('Runner', () => {
       });
     });
 
+    it('outputs an error audit result when devtoolsLog required but not provided', async () => {
+      const config = new Config({
+        settings: {
+          auditMode: __dirname + '/fixtures/artifacts/empty-artifacts/',
+        },
+        audits: [
+          // requires devtoolsLogs[Audit.DEFAULT_PASS]
+          'is-on-https',
+        ],
+      });
+
+      const results = await Runner.run({}, {config});
+      const auditResult = results.lhr.audits['is-on-https'];
+      assert.strictEqual(auditResult.score, null);
+      assert.strictEqual(auditResult.scoreDisplayMode, 'error');
+      assert.strictEqual(auditResult.errorMessage, 'Required devtoolsLogs gatherer did not run.');
+    });
+
     it('outputs an error audit result when missing a required artifact', () => {
       const config = new Config({
         settings: {