Inline rule in index

index.js

@@ -1,5 +1,59 @@
+// @ts-check
+"use strict"
+
 module.exports = {
   rules: {
-    "call-in-function": require("./lib/rules/call-in-function")
+    /**
+     * @type {import('eslint').Rule.RuleModule}
+     */
+    "call-in-function": {
+      create(context) {
+        const [options] = context.options
+
+        /** @type {string[]} */
+        const functions = options.functions || []
+        /** @type {string[]} */
+        const methods = options.methods || []
+
+        return {
+          CallExpression(node) {
+            if (node.type !== "CallExpression") return
+
+            const { callee } = node
+
+            const descriptor = { node, message: "" }
+
+            switch (callee.type) {
+              case "Identifier": {
+                if (!functions.includes(callee.name)) return
+                descriptor.message = `Function '${callee.name}' is must be called inside a function.`
+                break
+              }
+              case "MemberExpression": {
+                const { property } = callee
+                if (property.type !== "Identifier") return
+                if (!methods.includes(property.name)) return
+                descriptor.message = `Method '${property.name}' is must be called inside a function.`
+                break
+              }
+              default:
+                return
+            }
+
+            let parent = node.parent
+
+            // Look for a function declaration anywhere in the tree.
+            while (parent.parent) {
+              if (parent.type.match(/Function/)) {
+                return
+              }
+              parent = parent.parent
+            }
+
+            context.report(descriptor)
+          }
+        }
+      }
+    }
   }
 }

index.test.js

@@ -12,9 +12,9 @@ const parserOptions = {
 }
 
 const ruleTester = new RuleTester({ parserOptions })
-const rule = require("./lib/rules/call-in-function")
+const rules = require("./").rules
 
-ruleTester.run("call-in-function", rule, {
+ruleTester.run("call-in-function", rules["call-in-function"], {
   valid: [
     {
       code: `