SEO - description audit

lighthouse-core/audits/seo/meta-description.js

@@ -0,0 +1,52 @@
+/**
+ * @license Copyright 2017 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 Audit = require('../audit');
+
+class Description extends Audit {
+  /**
+   * @return {!AuditMeta}
+   */
+  static get meta() {
+    return {
+      category: 'Content Best Practices',
+      name: 'meta-description',
+      description: 'Document has a meta description',
+      failureDescription: 'Document does not have a meta description',
+      helpText: 'Meta descriptions may be included in search results to concisely summarize ' +
+          'page content. Read more in the ' +
+          '[Search Console Help page](https://support.google.com/webmasters/answer/35624?hl=en#1).',
+      requiredArtifacts: ['MetaDescription']
+    };
+  }
+
+  /**
+   * @param {!Artifacts} artifacts
+   * @return {!AuditResult}
+   */
+  static audit(artifacts) {
+    if (artifacts.MetaDescription === null) {
+      return {
+        rawValue: false,
+        debugString: 'Description meta tag is missing.'
+      };
+    }
+
+    if (artifacts.MetaDescription.trim().length === 0) {
+      return {
+        rawValue: false,
+        debugString: 'Description text is empty.'
+      };
+    }
+
+    return {
+      rawValue: true
+    };
+  }
+}
+
+module.exports = Description;

lighthouse-core/config/seo.js

@@ -7,6 +7,15 @@
 
 module.exports = {
   extends: 'lighthouse:default',
+  passes: [{
+    passName: 'defaultPass',
+    gatherers: [
+      'seo/meta-description',
+    ]
+  }],
+  audits: [
+    'seo/meta-description',
+  ],
   groups: {
     'seo-mobile': {
       title: 'Mobile Friendly',
@@ -28,7 +37,8 @@ module.exports = {
       description: 'These ensure your app is able to be understood by search engine crawlers.',
       audits: [
         {id: 'meta-viewport', weight: 1, group: 'seo-mobile'},
-        {id: 'document-title', weight: 1, group: 'seo-content'}
+        {id: 'document-title', weight: 1, group: 'seo-content'},
+        {id: 'meta-description', weight: 1, group: 'seo-content'}
       ]
     }
   }

lighthouse-core/gather/gatherers/seo/meta-description.js

@@ -0,0 +1,25 @@
+/**
+ * @license Copyright 2017 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 Gatherer = require('../gatherer');
+
+class MetaDescription extends Gatherer {
+
+  /**
+   * @param {{driver: !Object}} options Run options
+   * @return {!Promise<?string>} The value of the description meta's content attribute, or null
+   */
+  afterPass(options) {
+    const driver = options.driver;
+
+    return driver.querySelector('head meta[name="description"]')
+      .then(node => node && node.getAttribute('content'));
+  }
+}
+
+module.exports = MetaDescription;
+

lighthouse-core/runner.js

@@ -227,6 +227,7 @@ class Runner {
     const fileList = [
       ...fs.readdirSync(path.join(__dirname, './audits')),
       ...fs.readdirSync(path.join(__dirname, './audits/dobetterweb')).map(f => `dobetterweb/${f}`),
+      ...fs.readdirSync(path.join(__dirname, './audits/seo')).map(f => `seo/${f}`),
       ...fs.readdirSync(path.join(__dirname, './audits/accessibility'))
           .map(f => `accessibility/${f}`),
       ...fs.readdirSync(path.join(__dirname, './audits/byte-efficiency'))
@@ -245,6 +246,7 @@ class Runner {
   static getGathererList() {
     const fileList = [
       ...fs.readdirSync(path.join(__dirname, './gather/gatherers')),
+      ...fs.readdirSync(path.join(__dirname, './gather/gatherers/seo')).map(f => `seo/${f}`),
       ...fs.readdirSync(path.join(__dirname, './gather/gatherers/dobetterweb'))
           .map(f => `dobetterweb/${f}`)
     ];

lighthouse-core/test/audits/seo/meta-description-test.js

@@ -0,0 +1,37 @@
+/**
+ * @license Copyright 2017 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 Audit = require('../../../audits/seo/meta-description.js');
+const assert = require('assert');
+
+/* eslint-env mocha */
+
+describe('SEO: description audit', () => {
+  it('fails when HTML does not contain a description meta tag', () => {
+    return assert.equal(Audit.audit({
+      MetaDescription: null
+    }).rawValue, false);
+  });
+
+  it('fails when HTML contains an empty description meta tag', () => {
+    return assert.equal(Audit.audit({
+      MetaDescription: ''
+    }).rawValue, false);
+  });
+
+  it('fails when description consists only of whitespace', () => {
+    return assert.equal(Audit.audit({
+      MetaDescription: '    '
+    }).rawValue, false);
+  });
+
+  it('passes when a description text is provided', () => {
+    return assert.equal(Audit.audit({
+      MetaDescription: 'description text'
+    }).rawValue, true);
+  });
+});

lighthouse-core/test/gather/gatherers/seo/meta-description-test.js

@@ -0,0 +1,34 @@
+/**
+ * @license Copyright 2017 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';
+
+/* eslint-env mocha */
+
+const MetaDescriptionGather = require('../../../../gather/gatherers/seo/meta-description');
+const assert = require('assert');
+const EXAMPLE_DESCRIPTION = 'description text';
+let metaDescriptionGather;
+
+describe('Meta description gatherer', () => {
+  // Reset the Gatherer before each test.
+  beforeEach(() => {
+    metaDescriptionGather = new MetaDescriptionGather();
+  });
+
+  it('returns an artifact', () => {
+    return metaDescriptionGather.afterPass({
+      driver: {
+        querySelector() {
+          return Promise.resolve({
+            getAttribute: () => EXAMPLE_DESCRIPTION
+          });
+        }
+      }
+    }).then(artifact => {
+      assert.equal(artifact, EXAMPLE_DESCRIPTION);
+    });
+  });
+});