Add MD040 with tests.

README.md

@@ -70,6 +70,7 @@ cases come directly from that project.
 * **MD037** - Spaces inside emphasis markers
 * **MD038** - Spaces inside code span elements
 * **MD039** - Spaces inside link text
+* **MD040** - Fenced code blocks should have a language specified
 
 See [Rules.md](doc/Rules.md) for more details.
 
@@ -80,7 +81,7 @@ See [Rules.md](doc/Rules.md) for more details.
 * **blank_lines** - MD012, MD022, MD031, MD032
 * **blockquote** - MD027, MD028
 * **bullet** - MD004, MD005, MD006, MD007, MD032
-* **code** - MD014, MD031, MD038
+* **code** - MD014, MD031, MD038, MD040
 * **emphasis** - MD036, MD037
 * **hard_tab** - MD010
 * **headers** - MD001, MD002, MD003, MD018, MD019, MD020, MD021, MD022, MD023,
@@ -88,6 +89,7 @@ See [Rules.md](doc/Rules.md) for more details.
 * **hr** - MD035
 * **html** - MD033
 * **indentation** - MD005, MD006, MD007, MD027
+* **language** - MD040
 * **line_length** - MD013
 * **links** - MD011, MD034, MD039
 * **ol** - MD029, MD030, MD032

doc/Rules.md

@@ -853,3 +853,22 @@ This rule is triggered on links that have spaces surrounding the link text:
 To fix this, remove the spaces surrounding the link text:
 
     [a link](http://www.example.com/)
+
+## MD040 - Fenced code blocks should have a language specified
+
+Tags: code, language
+
+This rule is triggered when fenced code blocks are used, but a language isn't
+specified:
+
+    ```
+    #!/bin/bash
+    echo Hello world
+    ```
+
+To fix this, add a language specifier to the code block:
+
+    ```bash
+    #!/bin/bash
+    echo Hello world
+    ```

lib/rules.js

@@ -752,5 +752,19 @@ module.exports = [
           });
         });
     }
+  },
+
+  {
+    "name": "MD040",
+    "desc": "Fenced code blocks should have a language specified",
+    "tags": [ "code", "language" ],
+    "func": function MD040(params, errors) {
+      filterTokens(params.tokens, "fence")
+        .forEach(function forToken(token) {
+          if (!token.info.trim()) {
+            errors.push(token.lineNumber);
+          }
+        });
+    }
   }
 ];

style/relaxed.json

@@ -7,5 +7,6 @@
   "MD006": false,
   "MD007": false,
   "MD033": false,
-  "MD034": false
+  "MD034": false,
+  "MD040": false
 }

test/break-all-the-rules.md

@@ -46,6 +46,6 @@ Note: Can not break MD025 and MD002 in the same file
 1. list
 2. list {MD029}
 
-```
+```js
 ``` {MD031}
 * list {MD032}

test/code_block_dollar.md

@@ -29,5 +29,5 @@ The following code block doesn't have any dollar signs, and shouldn't fire:
 The following (fenced) code block doesn't have any content at all, and
 shouldn't fire:
 
-```
+```bash
 ```

test/fenced_code_blocks.md

@@ -19,3 +19,9 @@ echo "World"
 ~~~
 
 None of the above should trigger any heading related rules.
+
+```
+Code block without a language specifier
+```
+
+{MD040:23}

test/fenced_code_without_blank_lines.json

@@ -0,0 +1,4 @@
+{
+  "default": true,
+  "MD040": false
+}

test/lists_without_blank_lines.json

@@ -1,5 +1,6 @@
 {
   "default": true,
   "MD004": false,
-  "MD029": false
+  "MD029": false,
+  "MD040": false
 }

test/markdownlint-test.js

@@ -498,7 +498,7 @@ module.exports.badFileSync = function badFileSync(test) {
 };
 
 module.exports.readme = function readme(test) {
-  test.expect(92);
+  test.expect(95);
   var tagToRules = {};
   rules.forEach(function forRule(rule) {
     rule.tags.forEach(function forTag(tag) {
@@ -555,7 +555,7 @@ module.exports.readme = function readme(test) {
 };
 
 module.exports.doc = function doc(test) {
-  test.expect(143);
+  test.expect(147);
   fs.readFile("doc/Rules.md", shared.utf8Encoding,
     function readFile(err, contents) {
       test.ifError(err);