One more custom plugin

stylelint_plugins/declaration-colon-min-space-before.js

@@ -0,0 +1,52 @@
+const stylelint = require('stylelint');
+const { isNumber } = require('stylelint/lib/utils/validateTypes');
+
+const { report, ruleMessages, validateOptions } = stylelint.utils;
+const ruleName = 'naturalcrit/declaration-colon-min-space-before';
+const messages = ruleMessages(ruleName, {
+   expected: (num) => `Expected at least ${num} space${num == 1 ? '' : 's'} before ":"`
+});
+
+
+module.exports = stylelint.createPlugin(ruleName, function getPlugin(primaryOption, secondaryOptionObject, context) {
+   return function lint(postcssRoot, postcssResult) {
+
+       const validOptions = validateOptions(
+            postcssResult,
+            ruleName,
+            {
+                actual: primaryOption,
+                possible: [isNumber],
+            }
+       );
+
+       if (!validOptions) { //If the options are invalid, don't lint
+           return;
+       }
+       const isAutoFixing = Boolean(context.fix);
+
+       postcssRoot.walkDecls(decl => { //Iterate CSS declarations
+
+            let between = decl.raws.between;
+            const colonIndex = between.indexOf(":");
+
+            if (between.slice(0, colonIndex).length >= primaryOption) {
+              return;
+            }
+            if (isAutoFixing) { //We are in “fix” mode
+              decl.raws.between = between.slice(0, colonIndex).replace(/\s*$/, ' '.repeat(primaryOption)) + between.slice(colonIndex)
+            } else {
+              report({
+                  ruleName,
+                  result: postcssResult,
+                  message: messages.expected(primaryOption), // Build the reported message
+                  node: decl, // Specify the reported node
+                  word: ":", // Which exact word caused the error? This positions the error properly
+              });
+            }
+       });
+   };
+});
+
+module.exports.ruleName = ruleName;
+module.exports.messages = messages;