feat(guards): isNull

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

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

@@ -0,0 +1,12 @@
+/**
+ * @file Type Tests - isNull
+ * @module tutils/guards/tests/unit-d/isNull
+ */
+
+import type testSubject from '../is-null'
+
+describe('unit-d:guards/isNull', () => {
+  it('should guard null', () => {
+    expectTypeOf<typeof testSubject>().guards.toBeNull()
+  })
+})

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

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

src/guards/index.ts

@@ -15,4 +15,5 @@ export { default as isInt } from './is-int'
 export { default as isJwtType } from './is-jwt-type'
 export { default as isNIL } from './is-nil'
 export { default as isNodeEnv } from './is-node-env'
+export { default as isNull } from './is-null'
 export { default as isNumber } from './is-number'

src/guards/is-nil.ts

@@ -4,6 +4,7 @@
  */
 
 import type { NIL } from '#src/types'
+import isNull from './is-null'
 
 /**
  * Checks if the given `value` is `null` or `undefined`.
@@ -12,7 +13,7 @@ import type { NIL } from '#src/types'
  * @return {value is NIL} `true` if `value` is {@linkcode NIL}
  */
 const isNIL = (value: unknown): value is NIL => {
-  return value === null || value === undefined
+  return isNull(value) || value === undefined
 }
 
 export default isNIL

src/guards/is-null.ts

@@ -0,0 +1,14 @@
+/**
+ * @file Type Guards - isNull
+ * @module tutils/guards/isNull
+ */
+
+/**
+ * Checks if the given `value` is `null`.
+ *
+ * @param {unknown} value - Value to evaluate
+ * @return {value is null} `true` if `value` is `null`
+ */
+const isNull = (value: unknown): value is null => value === null
+
+export default isNull