fix(lint): re-arrange scripts (#36511)

tools/scripts/lint/linter/index.js

@@ -0,0 +1,25 @@
+const markdownlint = require('markdownlint');
+
+const lintPrism = require('./markdown-prism');
+const lintYAML = require('./markdown-yaml');
+
+function linter(rules) {
+  const lint = (file, next) => {
+    const options = {
+      files: [file.path],
+      config: rules,
+      customRules: [lintYAML, lintPrism]
+    };
+    markdownlint(options, function callback(err, result) {
+      const resultString = (result || '').toString();
+      if (resultString) {
+        process.exitCode = 1;
+        console.log(resultString);
+      }
+      if (next) next(err, file);
+    });
+  };
+  return lint;
+}
+
+module.exports = linter;

tools/scripts/lint/linter/markdown-prism.js

@@ -0,0 +1,44 @@
+const components = require(`prismjs/components`);
+
+module.exports = {
+  names: ['prism-langs'],
+  description: 'Code block languages should be supported by PrismJS',
+  tags: ['prism'],
+  function: function rule(params, onError) {
+    params.tokens
+      .filter(param => param.type === 'fence')
+      .forEach(codeBlock => {
+        // whitespace around the language is ignored by the parser, as is case:
+        const baseLang = codeBlock.info.trim().toLowerCase();
+        const lang = getBaseLanguageName(baseLang);
+        // Rule MD040 checks if the block has a language, so this rule only
+        // comes into play if a language has been specified.
+        if (baseLang && !lang) {
+          onError({
+            lineNumber: codeBlock.lineNumber,
+            detail: `\'${baseLang}\' is not recognised.`
+          });
+        }
+      });
+  }
+};
+
+/*
+ * This is the method used by https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-remark-prismjs/src/load-prism-language.js
+ */
+
+// Get the real name of a language given it or an alias
+const getBaseLanguageName = nameOrAlias => {
+  if (components.languages[nameOrAlias]) {
+    return nameOrAlias;
+  }
+  return Object.keys(components.languages).find(language => {
+    const { alias } = components.languages[language];
+    if (!alias) return false;
+    if (Array.isArray(alias)) {
+      return alias.includes(nameOrAlias);
+    } else {
+      return alias === nameOrAlias;
+    }
+  });
+};

tools/scripts/lint/linter/markdown-yaml.js

@@ -0,0 +1,24 @@
+const yaml = require('js-yaml');
+
+module.exports = {
+  names: ['yaml-linter'],
+  description: 'YAML code blocks should be valid',
+  tags: ['yaml'],
+  function: function rule(params, onError) {
+    params.tokens
+      .filter(param => param.type === 'fence')
+      .filter(param => param.info === 'yml' || param.info === 'yaml')
+      // TODO since the parser only looks for yml, should we reject yaml blocks?
+      .forEach(codeBlock => {
+        try {
+          yaml.safeLoad(codeBlock.content);
+        } catch (e) {
+          onError({
+            lineNumber: codeBlock.lineNumber,
+            detail: e.message,
+            context: codeBlock.line
+          });
+        }
+      });
+  }
+};