content: add tests for code blocks

Author: rajveermalviya

test/model/content_test.dart

@@ -293,6 +293,24 @@ void main() {
       QuotationNode([ParagraphNode(links: null, nodes: [TextNode('words')])]),
     ]);
 
+  testParse('parse code blocks, unknown span type',
+    '<div class="codehilite" data-code-language="Dart"><pre>'
+        '<span></span><code><span class="unknown">class</span>'
+        '\n</code></pre></div>', [
+          blockUnimplemented('<div class="codehilite" data-code-language="Dart"><pre>'
+            '<span></span><code><span class="unknown">class</span>'
+            '\n</code></pre></div>'),
+    ]);
+
+  testParse('parse code blocks, unsupported multiple span classes',
+    '<div class="codehilite" data-code-language="Dart"><pre>'
+        '<span></span><code><span class="class1 class2">class</span>'
+        '\n</code></pre></div>', [
+          blockUnimplemented('<div class="codehilite" data-code-language="Dart"><pre>'
+            '<span></span><code><span class="class1 class2">class</span>'
+            '\n</code></pre></div>'),
+    ]);
+
   testParse('parse code blocks, no language',
     // "```\nverb\natim\n```"
     '<div class="codehilite"><pre><span></span><code>verb\natim\n</code></pre></div>', const [

test/widgets/content_test.dart

@@ -161,4 +161,33 @@ void main() {
       check(tester.takeException()).isA<AssertionError>();
     });
   });
+
+  group("CodeBlock", () {
+    Future<void> prepareContent(WidgetTester tester, String html) async {
+      await tester.pumpWidget(MaterialApp(home: BlockContentList(nodes: parseContent(html).nodes)));
+      await tester.pump();
+      await tester.pump();
+    }
+
+    testWidgets('with syntax highlighting', (WidgetTester tester) async {
+      // "```dart\nclass A {}\n```"
+      await prepareContent(tester,
+        '<div class="codehilite" data-code-language="Dart"><pre>'
+          '<span></span><code><span class="kd">class</span><span class="w"> </span>'
+          '<span class="nc">A</span><span class="w"> </span><span class="p">{}</span>'
+          '\n</code></pre></div>'
+      );
+
+      expect(find.text('class A {}'), findsOneWidget);
+    });
+
+    testWidgets('without syntax highlighting', (WidgetTester tester) async {
+      // "```\nverb\natim\n```"
+      await prepareContent(tester,
+        '<div class="codehilite"><pre><span></span><code>verb\natim\n</code></pre></div>'
+      );
+
+      expect(find.text('verb\natim'), findsOneWidget);
+    });
+  });
 }