feat(types): TypeGuard

Signed-off-by: Lexus Drumgold <unicornware@flexdevelopment.llc>

src/types/__tests__/type-guard.spec-d.ts

@@ -0,0 +1,17 @@
+/**
+ * @file Type Tests - TypeGuard
+ * @module tutils/types/tests/unit-d/TypeGuard
+ */
+
+import type Vehicle from '#fixtures/types/vehicle'
+import type TestSubject from '../type-guard'
+
+describe('unit-d:types/TypeGuard', () => {
+  it('should guard T', () => {
+    // Arrange
+    type T = Vehicle
+
+    // Expect
+    expectTypeOf<TestSubject<T>>().guards.toEqualTypeOf<T>()
+  })
+})

src/types/index.ts

@@ -188,6 +188,7 @@ export type { default as Trim } from './trim'
 export type { default as TrimEnd } from './trim-end'
 export type { default as TrimStart } from './trim-start'
 export type { default as Tryit } from './tryit'
+export type { default as TypeGuard } from './type-guard'
 export type { default as TypedArray } from './typed-array'
 export type { default as UnionToIntersection } from './union-to-intersection'
 export type { default as UnionToTuple } from './union-to-tuple'

src/types/type-guard.ts

@@ -0,0 +1,18 @@
+/**
+ * @file Type Definitions - TypeGuard
+ * @module tutils/types/TypeGuard
+ */
+
+/**
+ * Checks if `value` is of type `T`.
+ *
+ * @see https://www.typescriptlang.org/docs/handbook/advanced-types.html#user-defined-type-guards
+ *
+ * @template T - Guarded value type
+ *
+ * @param {unknown} value - Value to check
+ * @return {value is T} `true` if `value` is of type `T`, `false` otherwise
+ */
+type TypeGuard<T> = (value: unknown) => value is T
+
+export type { TypeGuard as default }