add castArray tests

tests/casted/castArray.test-d.ts

@@ -0,0 +1,33 @@
+import * as _ from 'radashi'
+
+describe('castArray', () => {
+  test('mutable arrays', () => {
+    const input: number[] = [1, 2, 3]
+    expectTypeOf(_.castArray(input)).toEqualTypeOf<number[]>()
+  })
+  test('readonly arrays', () => {
+    const input: readonly number[] = [1, 2, 3]
+
+    // castArray clones the input array, so "readonly" is removed.
+    expectTypeOf(_.castArray(input)).toEqualTypeOf<number[]>()
+  })
+  test('union type with array type and primitive type', () => {
+    const input = 1 as number[] | number
+    const output = _.castArray(input)
+
+    expectTypeOf(output).toEqualTypeOf<number[] | [number]>()
+  })
+  test('union type with two array types', () => {
+    const input = [1, 2, 3] as number[] | readonly string[]
+    const output = _.castArray(input)
+
+    expectTypeOf(output).toEqualTypeOf<number[] | string[]>()
+  })
+  test('primitive types', () => {
+    expectTypeOf(_.castArray(1)).toEqualTypeOf<[number]>()
+    expectTypeOf(_.castArray('a')).toEqualTypeOf<[string]>()
+    expectTypeOf(_.castArray(true)).toEqualTypeOf<[true] | [false]>()
+    expectTypeOf(_.castArray(null)).toEqualTypeOf<[null]>()
+    expectTypeOf(_.castArray(undefined)).toEqualTypeOf<[undefined]>()
+  })
+})

tests/casted/castArray.test.ts

@@ -0,0 +1,31 @@
+import * as _ from 'radashi'
+
+describe('castArray', () => {
+  test('return the same array if input is an array', () => {
+    const input = [1, 2, 3]
+    expect(_.castArray(input)).toEqual(input)
+  })
+  test('return a new array with the same elements if input is an array', () => {
+    const input = [1, 2, 3]
+    const result = _.castArray(input)
+    expect(result).toEqual(input)
+    expect(result).not.toBe(input) // Ensure it's a copy
+  })
+  test('return an array with the input if input is not an array', () => {
+    const input = 1
+    expect(_.castArray(input)).toEqual([input])
+  })
+  test('handle primitives', () => {
+    expect(_.castArray(1)).toEqual([1])
+    expect(_.castArray('a')).toEqual(['a'])
+    expect(_.castArray(true)).toEqual([true])
+    expect(_.castArray(null)).toEqual([null])
+    expect(_.castArray(undefined)).toEqual([undefined])
+  })
+  test('handle objects and functions', () => {
+    const obj = { a: 1 }
+    const func = () => {}
+    expect(_.castArray(obj)).toEqual([obj])
+    expect(_.castArray(func)).toEqual([func])
+  })
+})