wip: type inference for useOptions

test-dts/useOptions.test-d.ts

@@ -0,0 +1,96 @@
+import { expectType, useOptions, Slots, describe } from './index'
+
+describe('no args', () => {
+  const { props, attrs, emit, slots } = useOptions()
+  expectType<{}>(props)
+  expectType<Record<string, unknown>>(attrs)
+  expectType<(...args: any[]) => void>(emit)
+  expectType<Slots>(slots)
+
+  // @ts-expect-error
+  props.foo
+  // should be able to emit anything
+  emit('foo')
+  emit('bar')
+})
+
+describe('with type arg', () => {
+  const { props, attrs, emit, slots } = useOptions<{
+    props: {
+      foo: string
+    }
+    emit: (e: 'change') => void
+  }>()
+
+  // explicitly declared type should be refined
+  expectType<string>(props.foo)
+  // @ts-expect-error
+  props.bar
+
+  emit('change')
+  // @ts-expect-error
+  emit()
+  // @ts-expect-error
+  emit('bar')
+
+  // non explicitly declared type should fallback to default type
+  expectType<Record<string, unknown>>(attrs)
+  expectType<Slots>(slots)
+})
+
+// with runtime arg
+describe('with runtime arg (array syntax)', () => {
+  const { props, emit } = useOptions({
+    props: ['foo', 'bar'],
+    emits: ['foo', 'bar']
+  })
+
+  expectType<{
+    foo?: any
+    bar?: any
+  }>(props)
+  // @ts-expect-error
+  props.baz
+
+  emit('foo')
+  emit('bar', 123)
+  // @ts-expect-error
+  emit('baz')
+})
+
+describe('with runtime arg (object syntax)', () => {
+  const { props, emit } = useOptions({
+    props: {
+      foo: String,
+      bar: {
+        type: Number,
+        default: 1
+      },
+      baz: {
+        type: Array,
+        required: true
+      }
+    },
+    emits: {
+      foo: () => {},
+      bar: null
+    }
+  })
+
+  expectType<{
+    foo?: string
+    bar: number
+    baz: unknown[]
+  }>(props)
+
+  props.foo && props.foo + 'bar'
+  props.bar + 1
+  // @ts-expect-error should be readonly
+  props.bar++
+  props.baz.push(1)
+
+  emit('foo')
+  emit('bar')
+  // @ts-expect-error
+  emit('baz')
+})