feat: ✨ Add IsNonNullish type - Check if a type is neither undefined …

…or null

.changeset/cyan-ducks-shout.md

@@ -0,0 +1,5 @@
+---
+"@crbroughton/ts-test-utils": minor
+---
+
+Add IsNonNullish type - Check if a type is neither undefined or null

README.md

@@ -17,7 +17,7 @@ A collection of helper TypeScript types to test other TypeScript types. This col
 - IsUndefined - Check if a type is undefined
 - IsNonUndefined - Check if a type is not undefined
 - IsNullish - Check if a type is either undefined or null
-
+- IsNonNullish - Check if a type is neither undefined or null
 ## Installation
 
 To install `ts-test-utils` with Bun, run the following command:

index.ts

@@ -36,3 +36,9 @@ export type IsNullish<T> =
     true
     : IsUndefined<T> extends true ?
       true : false
+
+export type IsNonNullish<T> =
+  IsNullable<T> extends true ?
+    false
+    : IsUndefined<T> extends true ?
+      false : true

tests/IsNonNullish.test.ts

@@ -0,0 +1,25 @@
+/* eslint-disable unused-imports/no-unused-vars */
+import { describe, it } from 'bun:test'
+import type { Expect, IsNonNullish } from '../index'
+
+describe('IsNonNullish tests', () => {
+  it('Passes the IsNonNullish test when the type is not nullish', () => {
+    type ResultNull = Expect<IsNonNullish<{ id: number }>>
+    //   ^?
+    type ResultUndefined = Expect<IsNonNullish<{ id: number }>>
+    //   ^?
+    type ResultBoth = Expect<IsNonNullish<{ id: number }>>
+    //   ^?
+  })
+  it('Failed the IsNonNullish test when the type is nullish', () => {
+    // @ts-expect-error - Fails the exclusion
+    type ResultNull = Expect<IsNonNullish<{ id: number } | null>>
+    //   ^?
+    // @ts-expect-error - Fails the exclusion
+    type ResultUndefined = Expect<IsNonNullish<{ id: number } | undefined>>
+    //   ^?
+    // @ts-expect-error - Fails the exclusion
+    type ResultBoth = Expect<IsNonNullish<{ id: number } | null | undefined>>
+    //   ^?
+  })
+})

tests/IsNullish.test.ts

@@ -2,16 +2,16 @@
 import { describe, it } from 'bun:test'
 import type { Expect, IsNullish } from '../index'
 
-describe('IsNullable tests', () => {
-  it('Passes the IsNullable test when the type is nullable', () => {
+describe('IsNullish tests', () => {
+  it('Passes the IsNullish test when the type is nullish', () => {
     type ResultNull = Expect<IsNullish<{ id: number } | null>>
     //   ^?
     type ResultUndefined = Expect<IsNullish<{ id: number } | undefined>>
     //   ^?
     type ResultBoth = Expect<IsNullish<{ id: number } | null | undefined>>
     //   ^?
   })
-  it('Failed the IsNullable test when the type is not nullable', () => {
+  it('Failed the IsNullish test when the type is not nullish', () => {
     // @ts-expect-error - Fails the exclusion
     type Result = Expect<IsNullish<{ id: string }>>
     //   ^?