fix(type): only return Promise with delay

package.json

@@ -26,7 +26,7 @@
   "homepage": "https://github.com/testing-library/user-event#readme",
   "files": [
     "dist",
-    "typings"
+    "typings/index.d.ts"
   ],
   "scripts": {
     "build": "kcd-scripts build",
@@ -35,7 +35,8 @@
     "test": "kcd-scripts test",
     "test:debug": "kcd-scripts --inspect-brk test --runInBand",
     "test:update": "npm test -- --updateSnapshot --coverage",
-    "validate": "kcd-scripts validate"
+    "validate": "kcd-scripts validate",
+    "typecheck": "tsc --project typings"
   },
   "dependencies": {
     "@babel/runtime": "^7.10.2"
@@ -46,7 +47,8 @@
     "@types/estree": "0.0.45",
     "is-ci": "^2.0.0",
     "jest-serializer-ansi": "^1.0.3",
-    "kcd-scripts": "^6.2.3"
+    "kcd-scripts": "^6.2.3",
+    "typescript": "^4.0.5"
   },
   "peerDependencies": {
     "@testing-library/dom": ">=7.21.4"

typings/index.d.ts

@@ -53,11 +53,11 @@ declare const userEvent: {
     files: FilesArgument,
     init?: UploadInitArgument,
   ) => void
-  type: (
+  type: <T extends ITypeOpts>(
     element: TargetElement,
     text: string,
-    userOpts?: ITypeOpts,
-  ) => Promise<void>
+    userOpts?: T,
+  ) => T extends {delay: number} ? Promise<void> : void
   tab: (userOpts?: ITabUserOptions) => void
   paste: (
     element: TargetElement,

typings/test.ts

@@ -0,0 +1,8 @@
+import userEvent, {TargetElement} from '.'
+
+declare const element: TargetElement
+type NotVoid = string | number | boolean | object | null
+
+userEvent.type(element, 'foo', {delay: 1}) as Promise<void>
+// @ts-expect-error No delay returns void
+userEvent.type(element, 'foo') as NotVoid

typings/tsconfig.json

@@ -0,0 +1,7 @@
+{
+  "compilerOptions": {
+    "lib": ["dom"],
+    "noEmit": true,
+    "strict": true
+  }
+}