feat(guards): isFunction

Signed-off-by: Lexus Drumgold <[email protected]>

src/guards/__tests__/is-function.spec-d.ts

@@ -0,0 +1,13 @@
+/**
+ * @file Type Tests - isFunction
+ * @module tutils/guards/tests/unit-d/isFunction
+ */
+
+import type { Fn } from '#src/types'
+import type testSubject from '../is-function'
+
+describe('unit-d:guards/isFunction', () => {
+  it('should guard Fn', () => {
+    expectTypeOf<typeof testSubject>().guards.toEqualTypeOf<Fn>()
+  })
+})

src/guards/__tests__/is-function.spec.ts

@@ -0,0 +1,16 @@
+/**
+ * @file Unit Tests - isFunction
+ * @module tutils/guards/tests/unit/isFunction
+ */
+
+import testSubject from '../is-function'
+
+describe('unit:guards/isFunction', () => {
+  it('should return false if value is not a function', () => {
+    expect(testSubject(faker.datatype.boolean())).to.be.false
+  })
+
+  it('should return true if value is a function', () => {
+    expect(testSubject(vi.fn())).to.be.true
+  })
+})

src/guards/index.ts

@@ -10,6 +10,7 @@ export { default as isBooleanish } from './is-booleanish'
 export { default as isEmptyString } from './is-empty-string'
 export { default as isEmptyValue } from './is-empty-value'
 export { default as isFloat } from './is-float'
+export { default as isFunction } from './is-function'
 export { default as isInt } from './is-int'
 export { default as isJwtType } from './is-jwt-type'
 export { default as isNIL } from './is-nil'

src/guards/is-function.ts

@@ -0,0 +1,16 @@
+/**
+ * @file Type Guards - isFunction
+ * @module tutils/guards/isFunction
+ */
+
+import type { Fn } from '#src/types'
+
+/**
+ * Checks if the given `value` is a function.
+ *
+ * @param {unknown} value - Value to evaluate
+ * @return {value is Fn} `true` if `value` is a function
+ */
+const isFunction = (value: unknown): value is Fn => typeof value === 'function'
+
+export default isFunction