Add stylelint-polaris/coverage rule (#7551)

.changeset/weak-islands-wait.md

@@ -0,0 +1,5 @@
+---
+'@shopify/stylelint-polaris': minor
+---
+
+Add `stylelint-polaris/coverage` rule

stylelint-polaris/plugins/coverage/index.js

@@ -0,0 +1,70 @@
+const stylelint = require('stylelint');
+
+const {isObject} = require('../../utils');
+
+const ruleName = 'stylelint-polaris/coverage';
+
+/**
+ * @typedef {{
+ *   [category: string]: import('stylelint').ConfigRules
+ * }} PrimaryOptions
+ */
+
+module.exports = stylelint.createPlugin(
+  ruleName,
+  /** @param {PrimaryOptions} primaryOptions */
+  (primaryOptions) => {
+    const isPrimaryOptionsValid = validatePrimaryOptions(primaryOptions);
+
+    const rules = !isPrimaryOptionsValid
+      ? []
+      : Object.entries(primaryOptions).flatMap(
+          ([categoryName, categoryConfigRules]) =>
+            Object.entries(categoryConfigRules).map(
+              ([categoryRuleName, categoryRuleSettings]) => ({
+                categoryRuleName,
+                categoryRuleSettings,
+                coverageRuleName: `${ruleName}/${categoryName}`,
+              }),
+            ),
+        );
+
+    return (root, result) => {
+      const validOptions = stylelint.utils.validateOptions(result, ruleName, {
+        actual: isPrimaryOptionsValid,
+      });
+
+      if (!validOptions) return;
+
+      for (const rule of rules) {
+        const {categoryRuleName, categoryRuleSettings, coverageRuleName} = rule;
+
+        stylelint.utils.checkAgainstRule(
+          {
+            ruleName: categoryRuleName,
+            ruleSettings: categoryRuleSettings,
+            root,
+          },
+          (warning) => {
+            stylelint.utils.report({
+              result,
+              node: warning.node,
+              ruleName: coverageRuleName,
+              message: warning.text.replace(categoryRuleName, coverageRuleName),
+            });
+          },
+        );
+      }
+    };
+  },
+);
+
+function validatePrimaryOptions(primaryOptions) {
+  if (!isObject(primaryOptions)) return false;
+
+  for (const categoryConfigRules of Object.values(primaryOptions)) {
+    if (!isObject(categoryConfigRules)) return false;
+  }
+
+  return true;
+}

stylelint-polaris/plugins/coverage/index.test.js

@@ -0,0 +1,29 @@
+const {ruleName} = require('.');
+
+const config = {
+  motion: {
+    'at-rule-disallowed-list': [['keyframes'], {severity: 'warning'}],
+  },
+};
+
+testRule({
+  ruleName,
+  plugins: [__dirname],
+  config,
+  customSyntax: 'postcss-scss',
+  accept: [
+    {
+      code: '@media (min-width: 320px) {}',
+      description: 'Uses allowed at-rule',
+    },
+  ],
+
+  reject: [
+    {
+      code: '@keyframes foo {}',
+      description: 'Uses disallowed at-rule',
+      message:
+        'Unexpected at-rule "keyframes" (stylelint-polaris/coverage/motion)',
+    },
+  ],
+});

stylelint-polaris/utils/index.js

@@ -181,6 +181,17 @@ function isNumber(value) {
   return typeof value === 'number' || value instanceof Number;
 }
 
+/**
+ * Checks if the value is an object and not an array or null.
+ * https://github.com/jonschlinkert/isobject/blob/15d5d58ea9fbc632dffd52917ac6791cd92251ab/index.js#L9
+ * @param {unknown} value
+ */
+function isObject(value) {
+  return (
+    value != null && typeof value === 'object' && Array.isArray(value) === false
+  );
+}
+
 /**
  * Checks if the value is a RegExp object.
  * @param {unknown} value
@@ -212,6 +223,7 @@ module.exports.hasScssInterpolation = hasScssInterpolation;
 module.exports.isBoolean = isBoolean;
 module.exports.isCustomProperty = isCustomProperty;
 module.exports.isNumber = isNumber;
+module.exports.isObject = isObject;
 module.exports.isRegExp = isRegExp;
 module.exports.isScssInterpolation = isScssInterpolation;
 module.exports.isString = isString;