ESLint rule to detect components contains prop href but not rel

.eslintplugin.js

@@ -1,3 +1,4 @@
 exports.rules = {
   i18n: require('./scripts/eslint-plugin-i18n/i18n'),
+  'href-with-rel': require('./scripts/eslint-plugin-rel/rel')
 };

.eslintrc.js

@@ -36,6 +36,7 @@ module.exports = {
   rules: {
     "prefer-template": "error",
     "local/i18n": "error",
+    "local/href-with-rel": "error",
     "no-use-before-define": "off",
     "quotes": ["warn", "single", "avoid-escape"],
 

scripts/eslint-plugin-rel/rel.js

@@ -0,0 +1,41 @@
+module.exports = {
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'Enforce rel prop if href exists',
+    },
+  },
+  create: function(context) {
+    return {
+      /**
+       * Props of any component is defined in ArrowFunctions
+       * Example: const EuiButton = ({ foo, bar }) => {};
+       */
+      ArrowFunctionExpression(node) {
+        // Functional component contains only single argument
+        if (node.params && node.params.length === 1) {
+          // Extract object => { foo, bar }
+          const objectPattern = node.params[0];
+
+          if (objectPattern.properties && objectPattern.properties.length) {
+            // Iterate each Object property to find href or rel
+            let href = -1;
+            let rel = -1;
+            objectPattern.properties.forEach((property, index) => {
+              if (property.key && property.key.name === 'href') href = index;
+              if (property.key && property.key.name === 'rel') rel = index;
+            });
+
+            // Error => If href is preset and rel is not preset
+            if (href !== -1 && rel === -1) {
+              context.report({
+                node: objectPattern.properties[href],
+                message: 'Props must contain rel if href is defined',
+              });
+            }
+          }
+        }
+      },
+    };
+  },
+};

scripts/eslint-plugin-rel/rel.test.js

@@ -0,0 +1,27 @@
+const rule = require('./rel');
+const RuleTester = require('eslint').RuleTester;
+
+const ruleTester = new RuleTester({
+  parser: 'babel-eslint',
+});
+
+const valid = [
+  'const Component = ({ href, rel }) => {};',
+  'const Component = ({ foo, bar, baz}) => {};',
+];
+
+const invalid = [
+  {
+    code: 'const Component = ({ href }) => {};',
+    errors: [
+      {
+        message: 'Props must contain rel if href is defined',
+      },
+    ],
+  },
+];
+
+ruleTester.run('href-with-rel', rule, {
+  valid,
+  invalid,
+});