fix: stricter props types

At the moment, `mount()` offers [strong typing][1] of props, but this
strong typing is lost when dealing with the `VueWrapper` through either
the `props()` or `setProps()` methods.

This change strengthens the typing of these methods to help raise
compile-time errors when trying to get or set incorrect props.

[1]: https://github.com/vuejs/test-utils/blob/11b34745e8e66fc747881dfb1ce94cef537c455e/src/types.ts#L44

Author: alecgibson

src/vueWrapper.ts

@@ -215,10 +215,14 @@ export class VueWrapper<
     return this.componentVM
   }
 
-  props(): { [key: string]: any }
-  props(selector: string): any
-  props(selector?: string): { [key: string]: any } | any {
-    const props = this.componentVM.$props as { [key: string]: any }
+  props(): T['$props']
+  props<Selector extends keyof T['$props']>(
+    selector: Selector
+  ): T['$props'][Selector]
+  props<Selector extends keyof T['$props']>(
+    selector?: Selector
+  ): T['$props'] | T['$props'][Selector] {
+    const props = this.componentVM.$props as T['$props']
     return selector ? props[selector] : props
   }
 
@@ -240,7 +244,7 @@ export class VueWrapper<
     return nextTick()
   }
 
-  setProps(props: Record<string, unknown>): Promise<void> {
+  setProps(props: T['$props']): Promise<void> {
     // if this VM's parent is not the root or if setProps does not exist, error out
     if (this.vm.$parent !== this.rootVM || !this.__setProps) {
       throw Error('You can only use setProps on your mounted component')

test-dts/wrapper.d-test.ts

@@ -116,4 +116,29 @@ expectType<boolean>(domWrapper.classes('class'))
 
 // props
 expectType<{ [key: string]: any }>(wrapper.props())
-expectType<any>(wrapper.props('prop'))
+
+const ComponentWithProps = defineComponent({
+  props: {
+    foo: String,
+    bar: Number,
+  },
+})
+
+const propsWrapper = mount(ComponentWithProps);
+
+propsWrapper.setProps({foo: 'abc'})
+propsWrapper.setProps({foo: 'abc', bar: 123})
+// @ts-expect-error :: should require string
+propsWrapper.setProps({foo: 123})
+// @ts-expect-error :: unknown prop
+propsWrapper.setProps({badProp: true})
+
+expectType<string | undefined>(propsWrapper.props().foo)
+expectType<number | undefined>(propsWrapper.props().bar)
+// @ts-expect-error :: unknown prop
+propsWrapper.props().badProp;
+
+expectType<string | undefined>(propsWrapper.props('foo'))
+expectType<number | undefined>(propsWrapper.props('bar'))
+// @ts-expect-error :: unknown prop
+propsWrapper.props('badProp')