feat: ✨ Add the NotEquals type - Checks if a type does not equal anot…

…her type

.changeset/nasty-needles-fold.md

@@ -0,0 +1,5 @@
+---
+"@crbroughton/ts-test-utils": minor
+---
+
+Add the NotEquals type - Checks if a type does not equal another type

index.ts

@@ -2,6 +2,8 @@ export type Expect<T extends true> = T
 
 export type Equals<T, U> = T extends U ? U extends T ? true : false : false
 
+export type NotEquals<X, Y> = true extends Equals<X, Y> ? false : true
+
 export type Includes<T extends U, U> = T extends U ? true : false
 
 export type Excludes<T, U> = [T] extends [U] ? false : true

tests/NotEquals.test.ts

@@ -0,0 +1,20 @@
+/* eslint-disable unused-imports/no-unused-vars */
+import { describe, it } from 'bun:test'
+import type { Expect, NotEquals } from '../index'
+
+describe('NotEquals tests', () => {
+  it('Passes the equality test when the types are not equal', () => {
+    type ResultBoolean = Expect<NotEquals<true, false>>
+    //   ^?
+    type ResultRecord = Expect<NotEquals<{ id: number }, { id: string }>>
+    //   ^?
+  })
+  it('Fails the equality test when the types are equal', () => {
+    // @ts-expect-error - Boolean values failing the equality checker
+    type ResultBoolean = Expect<NotEquals<true, true>>
+    //   ^?
+    // @ts-expect-error - Object / Record failing the equality checker
+    type ResultRecord = Expect<NotEquals<{ id: number }, { id: number }>>
+    //   ^?
+  })
+})