--- /dev/null
+"use strict";
+
+const ruleMessages = require("../../utils/ruleMessages");
+const selectorCombinatorSpaceChecker = require("../selectorCombinatorSpaceChecker");
+const validateOptions = require("../../utils/validateOptions");
+const whitespaceChecker = require("../../utils/whitespaceChecker");
+
+const ruleName = "selector-combinator-space-before";
+
+const messages = ruleMessages(ruleName, {
+ expectedBefore: combinator => `Expected single space before "${combinator}"`,
+ rejectedBefore: combinator => `Unexpected whitespace before "${combinator}"`
+});
+
+const rule = function(expectation) {
+ const checker = whitespaceChecker("space", expectation, messages);
+ return (root, result) => {
+ const validOptions = validateOptions(result, ruleName, {
+ actual: expectation,
+ possible: ["always", "never"]
+ });
+ if (!validOptions) {
+ return;
+ }
+
+ selectorCombinatorSpaceChecker({
+ root,
+ result,
+ locationChecker: checker.before,
+ locationType: "before",
+ checkedRuleName: ruleName
+ });
+ };
+};
+
+rule.ruleName = ruleName;
+rule.messages = messages;
+module.exports = rule;