Add new warning to package warning definitions

Author: parlough

lib/src/model/documentation_comment.dart

@@ -697,7 +697,7 @@ mixin DocumentationComment
       if (result.isEmpty) {
         warn(PackageWarning.missingCodeBlockLanguage,
             message:
-                'A fenced code block in Markdown should have a language specified.');
+                'A fenced code block in Markdown should have a language specified');
       }
     });
   }

lib/src/warnings.dart

@@ -256,6 +256,16 @@ const Map<PackageWarning, PackageWarningDefinition> packageWarningDefinitions =
       // Defaults to ignore as this doesn't impact the docs severely but is
       // useful for debugging package structure.
       defaultWarningMode: PackageWarningMode.ignore),
+  PackageWarning.missingCodeBlockLanguage: PackageWarningDefinition(
+      PackageWarning.missingCodeBlockLanguage,
+      'missing-code-block-language',
+      'A fenced code block is missing a specified language.',
+      longHelp: [
+        'To enable proper syntax highlighting of Markdown code blocks,',
+        'Dartdoc requires code blocks to specify the language used after',
+        'the initial declaration.  As an example, to specify Dart you would',
+        'specify ```dart or ~~~dart.'
+      ]),
 };
 
 /// Something that package warnings can be called on.  Optionally associated

test/documentation_comment_test.dart

@@ -856,7 +856,7 @@ Text.
           packageGraph.packageWarningCounter.hasWarning(
               libraryModel,
               PackageWarning.missingCodeBlockLanguage,
-              'A fenced code block in Markdown should have a language specified.'),
+              'A fenced code block in Markdown should have a language specified'),
           isTrue);
     });
 
@@ -872,7 +872,7 @@ Text.
           packageGraph.packageWarningCounter.hasWarning(
               libraryModel,
               PackageWarning.missingCodeBlockLanguage,
-              'A fenced code block in Markdown should have a language specified.'),
+              'A fenced code block in Markdown should have a language specified'),
           isTrue);
     });
 
@@ -888,7 +888,7 @@ Text.
           packageGraph.packageWarningCounter.hasWarning(
               libraryModel,
               PackageWarning.missingCodeBlockLanguage,
-              'A fenced code block in Markdown should have a language specified.'),
+              'A fenced code block in Markdown should have a language specified'),
           isFalse);
     });
 
@@ -902,7 +902,7 @@ Text.
           packageGraph.packageWarningCounter.hasWarning(
               libraryModel,
               PackageWarning.missingCodeBlockLanguage,
-              'A fenced code block in Markdown should have a language specified.'),
+              'A fenced code block in Markdown should have a language specified'),
           isFalse);
     });
   }, onPlatform: {