Add fenced code block style rule (#224) (fixes #223).

README.md

@@ -90,6 +90,7 @@ playground for learning and exploring.
 * **[MD045](doc/Rules.md#md045)** *no-alt-text* - Images should have alternate text (alt text)
 * **[MD046](doc/Rules.md#md046)** *code-block-style* - Code block style
 * **[MD047](doc/Rules.md#md047)** *single-trailing-newline* - Files should end with a single newline character
+* **[MD048](doc/Rules.md#md048)** *code-fence-style* - Code fence style
 
 See [Rules.md](doc/Rules.md) for more details.
 
@@ -109,7 +110,7 @@ Tags group related rules and can be used to enable/disable multiple rules at onc
 * **blank_lines** - MD012, MD022, MD031, MD032, MD047
 * **blockquote** - MD027, MD028
 * **bullet** - MD004, MD005, MD006, MD007, MD032
-* **code** - MD014, MD031, MD038, MD040, MD046
+* **code** - MD014, MD031, MD038, MD040, MD046, MD048
 * **emphasis** - MD036, MD037
 * **hard_tab** - MD010
 * **headers** - MD001, MD002, MD003, MD018, MD019, MD020, MD021, MD022, MD023,

doc/Rules.md

@@ -1601,3 +1601,41 @@ To fix the violation, add a newline character to the end of the file:
 This file ends with a newline.
 [EOF]
 ```
+
+<a name="md048"></a>
+
+## MD048 - Code fence style
+
+Tags: code
+
+Aliases: code-fence-style
+
+Parameters: style ("consistent", "tilde", "backtick"; default "consistent")
+
+This rule is triggered when the symbols used in the document for fenced code blocks do not match the configured code fence style:
+
+````markdown
+```ruby
+# Fenced code
+```
+
+~~~ruby
+# Fenced code
+~~~
+````
+
+To fix this issue, use the configured code fence style throughout the
+document:
+
+````markdown
+```ruby
+# Fenced code
+```
+
+```ruby
+# Fenced code
+```
+````
+
+The configured list style can be a specific symbol to use (backtick, tilde), or
+can require that usage be consistent within the document.

lib/md048.js

@@ -0,0 +1,38 @@
+// @ts-check
+
+"use strict";
+
+const { addErrorDetailIf } = require("../helpers");
+
+function fencedCodeBlockStyleFor(markup) {
+  switch (markup[0]) {
+    case "~":
+      return "tilde";
+    default:
+      return "backtick";
+  }
+}
+
+module.exports = {
+  "names": [ "MD048", "code-fence-style" ],
+  "description": "Code fence style",
+  "tags": [ "code" ],
+  "function": function MD048(params, onError) {
+    const style = params.config.style || "consistent";
+    let expectedStyle = style;
+    params.tokens
+      .filter((token) => token.type === "fence")
+      .forEach((fenceToken) => {
+        const { lineNumber, markup } = fenceToken;
+        if (expectedStyle === "consistent") {
+          expectedStyle = fencedCodeBlockStyleFor(markup);
+        }
+        addErrorDetailIf(
+          onError,
+          lineNumber,
+          expectedStyle,
+          fencedCodeBlockStyleFor(markup)
+        );
+      });
+  }
+};

lib/rules.js

@@ -50,7 +50,8 @@ const rules = [
   require("./md044"),
   require("./md045"),
   require("./md046"),
-  require("./md047")
+  require("./md047"),
+  require("./md048")
 ];
 rules.forEach((rule) => {
   const name = rule.names[0].toLowerCase();

schema/build-config-schema.js

@@ -334,6 +334,20 @@ rules.forEach(function forRule(rule) {
         }
       };
       break;
+    case "MD048":
+      scheme.properties = {
+        "style": {
+          "description": "Code fence syle",
+          "type": "string",
+          "enum": [
+            "consistent",
+            "backtick",
+            "tilde"
+          ],
+          "default": "consistent"
+        }
+      };
+      break;
     default:
       custom = false;
       break;

schema/markdownlint-config-schema.json

@@ -1339,6 +1339,48 @@
       "type": "boolean",
       "default": true
     },
+    "MD048": {
+      "description": "MD048/code-fence-style - Code fence style",
+      "type": [
+        "boolean",
+        "object"
+      ],
+      "default": true,
+      "properties": {
+        "style": {
+          "description": "Code fence syle",
+          "type": "string",
+          "enum": [
+            "consistent",
+            "backtick",
+            "tilde"
+          ],
+          "default": "consistent"
+        }
+      },
+      "additionalProperties": false
+    },
+    "code-fence-style": {
+      "description": "MD048/code-fence-style - Code fence style",
+      "type": [
+        "boolean",
+        "object"
+      ],
+      "default": true,
+      "properties": {
+        "style": {
+          "description": "Code fence syle",
+          "type": "string",
+          "enum": [
+            "consistent",
+            "backtick",
+            "tilde"
+          ],
+          "default": "consistent"
+        }
+      },
+      "additionalProperties": false
+    },
     "headings": {
       "description": "headings - MD001, MD002, MD003, MD018, MD019, MD020, MD021, MD022, MD023, MD024, MD025, MD026, MD036, MD041, MD043",
       "type": "boolean",
@@ -1390,7 +1432,7 @@
       "default": true
     },
     "code": {
-      "description": "code - MD014, MD031, MD038, MD040, MD046",
+      "description": "code - MD014, MD031, MD038, MD040, MD046, MD048",
       "type": "boolean",
       "default": true
     },

test/break-all-the-rules.md

@@ -74,6 +74,10 @@ Code `with ` space {MD038}
 code fence without language {MD040:73} {MD046:73}
 ```
 
+~~~js
+code fence with different style {MD048:77} {MD046:77}
+~~~
+
 [empty link]() {MD042}
 
 markdownLint {MD044}

test/code_fence_style_backtick.json

@@ -0,0 +1,6 @@
+{
+  "default": true,
+  "MD048": {
+    "style": "backtick"
+  }
+}

test/code_fence_style_backtick.md

@@ -0,0 +1,19 @@
+```text
+This is a code block
+```
+
+~~~text
+This is {MD048:5} a code block
+~~~
+
+```text
+~~~
+This is fine
+~~~
+```
+
+~~~text
+```
+This is not {MD048:15}
+```
+~~~

test/code_fence_style_tilde.json

@@ -0,0 +1,6 @@
+{
+  "default": true,
+  "MD048": {
+    "style": "tilde"
+  }
+}

test/code_fence_style_tilde.md

@@ -0,0 +1,19 @@
+```text
+This is {MD048:1} a code block
+```
+
+~~~text
+This is a code block
+~~~
+
+```text
+~~~
+This is not fine {MD048:9}
+~~~
+```
+
+~~~text
+```
+This is
+```
+~~~

test/detailed-results-MD041-MD050.md

@@ -24,4 +24,8 @@ Fenced code
 
     Indented code
 
+~~~text
+Fenced code
+~~~
+
 Missing newline character

test/detailed-results-MD041-MD050.md.fixed

@@ -24,4 +24,8 @@ Fenced code
 
     Indented code
 
+~~~text
+Fenced code
+~~~
+
 Missing newline character

test/detailed-results-MD041-MD050.results.json

@@ -45,7 +45,7 @@
         "errorRange": [25, 13]
     },
     {
-        "lineNumber": 27,
+        "lineNumber": 31,
         "ruleNames": [ "MD043", "required-headings", "required-headers" ],
         "ruleDescription": "Required heading structure",
         "ruleInformation": "https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/Rules.md#md043",
@@ -99,12 +99,21 @@
         "errorRange": null
     },
     {
-        "lineNumber": 27,
+        "lineNumber": 31,
         "ruleNames": [ "MD047", "single-trailing-newline" ],
         "ruleDescription": "Files should end with a single newline character",
         "ruleInformation": "https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/Rules.md#md047",
         "errorDetail": null,
         "errorContext": null,
         "errorRange": [ 25, 1 ]
+    },
+    {
+        "lineNumber": 27,
+        "ruleNames": [ "MD048", "code-fence-style" ],
+        "ruleDescription": "Code fence style",
+        "ruleInformation": "https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/Rules.md#md048",
+        "errorDetail": "Expected: backtick; Actual: tilde",
+        "errorContext": null,
+        "errorRange": null
     }
 ]

test/fenced_code_blocks.md

@@ -24,4 +24,4 @@ None of the above should trigger any heading related rules.
 Code block without a language specifier
 ```
 
-{MD040:23}
+{MD040:23} {MD048:13}

test/fenced_code_with_nesting.md

@@ -4,7 +4,7 @@ text {MD031:4}
 ```fence
 code {MD031:6}
 ```
-text {MD031:8}
+text {MD031:8} {MD048:8}
 ~~~fence
 code
 ~~~
@@ -14,7 +14,7 @@ text {MD031:10} {MD031:12}
 code
 ~~~
 ```
-text {MD031:16} {MD031:18}
+text {MD031:16} {MD031:18} {MD048:18}
 ~~~fence
 ```fence
 code
@@ -28,7 +28,7 @@ code
 ~~~
 
 ```
-text {MD031:30} {MD031:32}
+text {MD031:30} {MD031:32} {MD048:32}
 ~~~fence
 
 ```fence
@@ -41,7 +41,7 @@ text {MD031:38} {MD031:40}
 code
 ~~~
 ```
-text {MD031:43} {MD031:45}
+text {MD031:43} {MD031:45} {MD048:45}
 ~~~fence
 code
 ```
@@ -52,7 +52,7 @@ text {MD031:48} {MD031:50}
 code
 ```
 ````
-text {MD031:54} {MD031:56}
+text {MD031:54} {MD031:56} {MD048:56}
 ~~~~fence
 ~~~fence
 code
@@ -64,7 +64,7 @@ text {MD031:60} {MD031:62}
 code
 ```
 `````
-text {MD031:66} {MD031:68}
+text {MD031:66} {MD031:68} {MD048:68}
 ~~~~fence
 ~~~fence
 code

test/markdownlint-test.js

@@ -1124,7 +1124,7 @@ module.exports.styleAll = function styleAll(test) {
         "MD019": [ 27 ],
         "MD020": [ 29 ],
         "MD021": [ 31 ],
-        "MD022": [ 82 ],
+        "MD022": [ 86 ],
         "MD023": [ 40 ],
         "MD024": [ 35 ],
         "MD026": [ 40 ],
@@ -1143,10 +1143,11 @@ module.exports.styleAll = function styleAll(test) {
         "MD039": [ 71 ],
         "MD040": [ 73 ],
         "MD041": [ 1 ],
-        "MD042": [ 77 ],
+        "MD042": [ 81 ],
-        "MD045": [ 81 ],
+        "MD045": [ 85 ],
-        "MD046": [ 49, 73 ],
+        "MD046": [ 49, 73, 77 ],
-        "MD047": [ 84 ]
+        "MD047": [ 88 ],
+        "MD048": [ 77 ]
       }
     };
     test.deepEqual(actualResult, expectedResult, "Undetected issues.");
@@ -1175,7 +1176,7 @@ module.exports.styleRelaxed = function styleRelaxed(test) {
         "MD019": [ 27 ],
         "MD020": [ 29 ],
         "MD021": [ 31 ],
-        "MD022": [ 82 ],
+        "MD022": [ 86 ],
         "MD023": [ 40 ],
         "MD024": [ 35 ],
         "MD026": [ 40 ],
@@ -1184,10 +1185,11 @@ module.exports.styleRelaxed = function styleRelaxed(test) {
         "MD032": [ 7, 8, 51 ],
         "MD035": [ 61 ],
         "MD036": [ 65 ],
-        "MD042": [ 77 ],
+        "MD042": [ 81 ],
-        "MD045": [ 81 ],
+        "MD045": [ 85 ],
-        "MD046": [ 49, 73 ],
+        "MD046": [ 49, 73, 77 ],
-        "MD047": [ 84 ]
+        "MD047": [ 88 ],
+        "MD048": [ 77 ]
       }
     };
     test.deepEqual(actualResult, expectedResult, "Undetected issues.");
@@ -1430,7 +1432,7 @@ module.exports.missingStringValue = function missingStringValue(test) {
 };
 
 module.exports.readme = function readme(test) {
-  test.expect(113);
+  test.expect(115);
   const tagToRules = {};
   rules.forEach(function forRule(rule) {
     rule.tags.forEach(function forTag(tag) {
@@ -1499,7 +1501,7 @@ module.exports.readme = function readme(test) {
 };
 
 module.exports.doc = function doc(test) {
-  test.expect(328);
+  test.expect(336);
   fs.readFile("doc/Rules.md", helpers.utf8Encoding,
     function readFile(err, contents) {
       test.ifError(err);
@@ -2787,7 +2789,7 @@ module.exports.configBadHybridSync = function configBadHybridSync(test) {
 
 module.exports.allBuiltInRulesHaveValidUrl =
   function allBuiltInRulesHaveValidUrl(test) {
-    test.expect(129);
+    test.expect(132);
     rules.forEach(function forRule(rule) {
       test.ok(rule.information);
       test.ok(Object.getPrototypeOf(rule.information) === URL.prototype);