fix: add check to avoid converting 0 to undefined

packages/vitest/src/utils/base.ts

@@ -53,7 +53,9 @@ export function clone<T>(val: T): T {
  */
 
 export function toArray<T>(array?: Nullable<Arrayable<T>>): Array<T> {
-  array = array || []
+  if (array === null || array === undefined) 
+    array = []
+
   if (Array.isArray(array))
     return array
   return [array]

test/core/test/each.test.ts

@@ -57,3 +57,10 @@ describe.each([
     expect(a + b).not.toBeLessThan(expected)
   })
 })
+
+// issue #794
+describe.each([1, 2, 0])('%s (describe.each 1d)', (num) => {
+  test(`${num} is a number (describe.each 1d)`, () => {
+    expect(typeof num).toEqual('number')
+  })
+})

test/core/test/utils.spec.ts

@@ -1,5 +1,5 @@
 import { describe, expect, test } from 'vitest'
-import { assertTypes, deepMerge } from '../../../packages/vitest/src/utils'
+import { assertTypes, deepMerge, toArray } from '../../../packages/vitest/src/utils'
 import { deepMergeSnapshot } from '../../../packages/vitest/src/integrations/snapshot/port/utils'
 
 describe('assertTypes', () => {
@@ -96,3 +96,24 @@ describe('deepMerge', () => {
     })
   })
 })
+
+describe('toArray', () => {
+  test('number should be converted to array correctly', () => {
+    expect(toArray(0)).toEqual([0])
+    expect(toArray(1)).toEqual([1])
+    expect(toArray(2)).toEqual([2])
+  })
+
+  test('return empty array when given null or undefined', () => {
+    expect(toArray(null)).toEqual([])
+    expect(toArray(undefined)).toEqual([])
+  })
+
+  test('return the value as is when given the array', () => {
+    expect(toArray([1, 1, 2])).toEqual([1, 1, 2])
+  })
+
+  test('object should be stored in the array correctly', () => {
+    expect(toArray({ a: 1, b: 1, expected: 2 })).toEqual([{ a: 1, b: 1, expected: 2 }])
+  })
+})