test: test both number[] and never[]

tests/random/draw.test-d.ts

@@ -2,30 +2,27 @@ import * as _ from 'radashi'
 import { expectTypeOf } from 'vitest'
 
 describe('draw types', () => {
-  test('returns null given empty input', () => {
-    const list: unknown[] = []
-    const result = _.draw(list)
-    expect(result).toBeNull()
-  })
-  test('return type is null for empty array literal', () => {
+  test('return type with literal argument', () => {
     expectTypeOf(_.draw([])).toBeNull()
-  })
-  test('return type is not null for non-empty array literal', () => {
     expectTypeOf(_.draw([1, 2, 3])).toBeNumber()
   })
-  test('return type is possibly null for mutable array variables', () => {
+  test('return type with mutable variable', () => {
+    const neverList: never[] = []
     const emptyList: number[] = []
     const filledList = [1, 2, 3]
+
+    expectTypeOf(_.draw(neverList)).toEqualTypeOf<null>()
     expectTypeOf(_.draw(emptyList)).toEqualTypeOf<number | null>()
     expectTypeOf(_.draw(filledList)).toEqualTypeOf<number | null>()
   })
-  test('return type is possibly null for immutable empty array variables', () => {
+  test('return type with immutable variable', () => {
+    const neverList: never[] = [] as const
     const emptyList: number[] = [] as const
-    // FIXME: Can be narrowed to `null`
+    const filledList = [1, 2, 3] as const
+
+    expectTypeOf(_.draw(neverList)).toBeNull()
+    // FIXME: Can this be narrowed to `null`?
     expectTypeOf(_.draw(emptyList)).toEqualTypeOf<number | null>()
-  })
-  test('return type is not null for immutable non-empty array variables', () => {
-    const filledList = [1, 2, 4] as const
-    expectTypeOf(_.draw(filledList)).toEqualTypeOf<1 | 2 | 4>()
+    expectTypeOf(_.draw(filledList)).toEqualTypeOf<1 | 2 | 3>()
   })
 })