Update MD040/fenced-code-language to use case-sensitive comparison for allowed languages (fixes #627).

demo/markdownlint-browser.js

@@ -4167,16 +4167,13 @@ module.exports = {
     "tags": ["code", "language"],
     "function": function MD040(params, onError) {
         let allowed = params.config.allowed_languages;
-        allowed = Array.isArray(allowed) ?
+        allowed = Array.isArray(allowed) ? allowed : [];
-            allowed.map((lang) => lang.toLowerCase()) :
-            [];
         filterTokens(params, "fence", function forToken(token) {
-            const lang = token.info.trim();
+            const lang = token.info.trim().split(/\s+/u).shift();
             if (lang === "") {
                 addErrorContext(onError, token.lineNumber, token.line);
             }
-            else if (allowed.length > 0 &&
+            else if ((allowed.length > 0) && !allowed.includes(lang)) {
-                !allowed.includes(lang.toLowerCase())) {
                 addError(onError, token.lineNumber, `"${lang}" is not allowed`);
             }
         });

doc-build/md040.md

@@ -26,8 +26,8 @@ Plain text in a code block
 ````
 
 You can configure the `allowed_languages` parameter to specify a list of
-languages code blocks could use. The default value is `[]` which means any
+languages code blocks could use. Languages are case sensitive. The default value
-language specifier is valid.
+is `[]` which means any language specifier is valid.
 
 Rationale: Specifying a language improves content rendering by using the
 correct syntax highlighting for code. More information:

doc/Rules.md

@@ -1648,8 +1648,8 @@ Plain text in a code block
 ````
 
 You can configure the `allowed_languages` parameter to specify a list of
-languages code blocks could use. The default value is `[]` which means any
+languages code blocks could use. Languages are case sensitive. The default value
-language specifier is valid.
+is `[]` which means any language specifier is valid.
 
 Rationale: Specifying a language improves content rendering by using the
 correct syntax highlighting for code. More information:

doc/md040.md

@@ -36,8 +36,8 @@ Plain text in a code block
 ````
 
 You can configure the `allowed_languages` parameter to specify a list of
-languages code blocks could use. The default value is `[]` which means any
+languages code blocks could use. Languages are case sensitive. The default value
-language specifier is valid.
+is `[]` which means any language specifier is valid.
 
 Rationale: Specifying a language improves content rendering by using the
 correct syntax highlighting for code. More information:

lib/md040.js

@@ -10,17 +10,12 @@ module.exports = {
   "tags": [ "code", "language" ],
   "function": function MD040(params, onError) {
     let allowed = params.config.allowed_languages;
-    allowed = Array.isArray(allowed) ?
+    allowed = Array.isArray(allowed) ? allowed : [];
-      allowed.map((lang) => lang.toLowerCase()) :
-      [];
     filterTokens(params, "fence", function forToken(token) {
-      const lang = token.info.trim();
+      const lang = token.info.trim().split(/\s+/u).shift();
       if (lang === "") {
         addErrorContext(onError, token.lineNumber, token.line);
-      } else if (
+      } else if ((allowed.length > 0) && !allowed.includes(lang)) {
-        allowed.length > 0 &&
-        !allowed.includes(lang.toLowerCase())
-      ) {
         addError(
           onError,
           token.lineNumber,

test/md040-allowed_languages.md

@@ -12,13 +12,31 @@ Code block with `css` not in allowed_languages:
 body {}  {MD040:11}
 ```
 
+Code block with `MD` (uppercase) not in allowed_languages:
+
+```MD
+hello md {MD040:17}
+```
+
+Code block with `ts` (lowercase) not in allowed_languages:
+
+```ts
+let foo = "bar"; {MD040:23}
+```
+
 Code block with `js` in allowed_languages:
 
 ```js
 console.log('markdownlint')
 ```
 
-Code block with `scss` in allowed_languages:
+Code block with `js foo` allowed_languages:
+
+```js foo
+console.log('bar')
+```
+
+Code block with ` scss` (prefixed by a space) in allowed_languages: {MD038}
 
 ``` scss
 body {
@@ -28,15 +46,15 @@ body {
 }
 ```
 
-Code block with `md` in allowed_languages:
+Code block with `md` (lowercase) in allowed_languages:
 
-```MD
+```md
 hello md
 ```
 
-Code block with `TS` in allowed_languages:
+Code block with `TS` (uppercase) in allowed_languages:
 
-```ts
+```TS
 body {
   h1 {
     color: red;

test/snapshots/markdownlint-test-scenarios.js.md

@@ -29324,6 +29324,26 @@ Generated by [AVA](https://avajs.dev).
 
     {
       errors: [
+        {
+          errorContext: '` scss`',
+          errorDetail: null,
+          errorRange: [
+            17,
+            7,
+          ],
+          fixInfo: {
+            deleteCount: 5,
+            editColumn: 18,
+            insertText: 'scss',
+          },
+          lineNumber: 39,
+          ruleDescription: 'Spaces inside code span elements',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md038.md',
+          ruleNames: [
+            'MD038',
+            'no-space-in-code',
+          ],
+        },
         {
           errorContext: null,
           errorDetail: '"html" is not allowed',
@@ -29350,6 +29370,32 @@ Generated by [AVA](https://avajs.dev).
             'fenced-code-language',
           ],
         },
+        {
+          errorContext: null,
+          errorDetail: '"MD" is not allowed',
+          errorRange: null,
+          fixInfo: null,
+          lineNumber: 17,
+          ruleDescription: 'Fenced code blocks should have a language specified',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md040.md',
+          ruleNames: [
+            'MD040',
+            'fenced-code-language',
+          ],
+        },
+        {
+          errorContext: null,
+          errorDetail: '"ts" is not allowed',
+          errorRange: null,
+          fixInfo: null,
+          lineNumber: 23,
+          ruleDescription: 'Fenced code blocks should have a language specified',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md040.md',
+          ruleNames: [
+            'MD040',
+            'fenced-code-language',
+          ],
+        },
       ],
       fixed: `# md040-allowed_languages.md␊
       ␊
@@ -29365,13 +29411,31 @@ Generated by [AVA](https://avajs.dev).
       body {}  {MD040:11}␊
       \`\`\`␊
       ␊
+      Code block with \`MD\` (uppercase) not in allowed_languages:␊
+      ␊
+      \`\`\`MD␊
+      hello md {MD040:17}␊
+      \`\`\`␊
+      ␊
+      Code block with \`ts\` (lowercase) not in allowed_languages:␊
+      ␊
+      \`\`\`ts␊
+      let foo = "bar"; {MD040:23}␊
+      \`\`\`␊
+      ␊
       Code block with \`js\` in allowed_languages:␊
       ␊
       \`\`\`js␊
       console.log('markdownlint')␊
       \`\`\`␊
       ␊
-      Code block with \`scss\` in allowed_languages:␊
+      Code block with \`js foo\` allowed_languages:␊
+      ␊
+      \`\`\`js foo␊
+      console.log('bar')␊
+      \`\`\`␊
+      ␊
+      Code block with \`scss\` (prefixed by a space) in allowed_languages: {MD038}␊
       ␊
       \`\`\` scss␊
       body {␊
@@ -29381,15 +29445,15 @@ Generated by [AVA](https://avajs.dev).
       }␊
       \`\`\`␊
       ␊
-      Code block with \`md\` in allowed_languages:␊
+      Code block with \`md\` (lowercase) in allowed_languages:␊
       ␊
-      \`\`\`MD␊
+      \`\`\`md␊
       hello md␊
       \`\`\`␊
       ␊
-      Code block with \`TS\` in allowed_languages:␊
+      Code block with \`TS\` (uppercase) in allowed_languages:␊
       ␊
-      \`\`\`ts␊
+      \`\`\`TS␊
       body {␊
         h1 {␊
           color: red;␊