Koenig - Code card server-side rendering

refs https://github.com/TryGhost/Ghost/issues/9623
- add support for `code` card that renders into `<pre><code>...</code></pre>`
- render language class if one is provided

core/server/lib/mobiledoc/cards/code.js

@@ -0,0 +1,24 @@
+module.exports = {
+    name: 'code',
+    type: 'dom',
+    render(opts) {
+        let payload = opts.payload;
+        let dom = opts.env.dom;
+
+        if (!payload.code) {
+            return '';
+        }
+
+        let pre = dom.createElement('pre');
+        let code = dom.createElement('code');
+
+        if (payload.language) {
+            code.setAttribute('class', `language-${payload.language}`);
+        }
+
+        code.appendChild(dom.createTextNode(payload.code));
+        pre.appendChild(code);
+
+        return pre;
+    }
+};

core/server/lib/mobiledoc/cards/index.js

@@ -1,9 +1,10 @@
 'use strict';
 
-const hr = require('./hr');
-const html = require('./html');
-const image = require('./image');
-const markdown = require('./markdown');
-const cardMarkdown = require('./card-markdown');
-
-module.exports = [hr, html, image, markdown, cardMarkdown];
+module.exports = [
+    require('./card-markdown'),
+    require('./code'),
+    require('./hr'),
+    require('./html'),
+    require('./image'),
+    require('./markdown')
+];

core/test/unit/lib/mobiledoc/cards/code_spec.js

@@ -0,0 +1,48 @@
+'use strict';
+
+const should = require('should'); // jshint ignore:line
+const card = require('../../../../../server/lib/mobiledoc/cards/code');
+const SimpleDom = require('simple-dom');
+const serializer = new SimpleDom.HTMLSerializer(SimpleDom.voidMap);
+
+describe('Code card', function () {
+    it('Renders and escapes', function () {
+        let opts = {
+            env: {
+                dom: new SimpleDom.Document()
+            },
+            payload: {
+                code: '<p>Test</p>'
+            }
+        };
+
+        serializer.serialize(card.render(opts)).should.match('<pre><code>&lt;p&gt;Test&lt;/p&gt;</code></pre>');
+    });
+
+    it('Renders language class if provided', function () {
+        let opts = {
+            env: {
+                dom: new SimpleDom.Document()
+            },
+            payload: {
+                code: '<p>Test</p>',
+                language: 'html'
+            }
+        };
+
+        serializer.serialize(card.render(opts)).should.match('<pre><code class="language-html">&lt;p&gt;Test&lt;/p&gt;</code></pre>');
+    });
+
+    it('Renders nothing when payload is undefined', function () {
+        let opts = {
+            env: {
+                dom: new SimpleDom.Document()
+            },
+            payload: {
+                code: undefined
+            }
+        };
+
+        serializer.serialize(card.render(opts)).should.match('');
+    });
+});