Running type tests on CI

package.json

@@ -32,13 +32,14 @@
     }
   ],
   "scripts": {
-    "typescript:check": "yarn tsc --noEmit",
+    "typescript:check": "tsc --noEmit",
     "typescript:watch": "tsc --watch",
     "typescript:build": "tsc",
+    "typescript:test": "tsc ./test/type-tests/** --noEmit",
     "prettier:check": "prettier --debug-check $npm_package_config_prettier_target",
     "prettier:write": "prettier --write $npm_package_config_prettier_target",
-    "validate": "yarn typescript:check && yarn prettier:check",
-    "test": "yarn jest",
+    "validate": "yarn typescript:check && yarn typescript:test && yarn prettier:check",
+    "test": "tsc ./test/type-tests/** --noEmit",
     "size:check": "size-limit",
     "build:clean": "rimraf dist",
     "build": "yarn build:clean && yarn typescript:build",
@@ -47,7 +48,7 @@
   "devDependencies": {
     "@size-limit/preset-small-lib": "^7.0.5",
     "@types/jest": "^27.4.0",
-    "expect-type": "^0.13.0",
+    "expect-type": "^0.15.0",
     "jest": "^27.4.7",
     "prettier": "^2.5.1",
     "rimraf": "^3.0.2",

src/bind-all.ts

@@ -1,4 +1,4 @@
-import { Binding, InferEvent, InferEventType, Listener, UnbindFn } from './types';
+import { Binding, InferEventType, Listener, UnbindFn } from './types';
 import { bind } from './bind';
 
 function toOptions(value?: boolean | AddEventListenerOptions): AddEventListenerOptions | undefined {
@@ -46,11 +46,8 @@ export function bindAll<
         type: TTypes[K] | (string & {});
         listener: Listener<
           TTarget,
-          InferEvent<
-            TTarget,
-            // `& string` "cast" is not needed since TS 4.7 (but the repo is using TS 4.6 atm)
-            TTypes[K] & string
-          >
+          // `& string` "cast" is not needed since TS 4.7 (but the repo is using TS 4.6 atm)
+          TTypes[K] & string
         >;
         options?: boolean | AddEventListenerOptions;
       };

src/bind.ts

@@ -22,7 +22,7 @@ export function bind<TTarget extends EventTarget, TType extends InferEventType<T
     // however, doing that today breaks autocompletion
     // this is being fixed by https://github.com/microsoft/TypeScript/pull/51770 but we need wait for its release in TS 5.0
     type: TType | (string & {});
-    listener: Listener<TTarget, InferEvent<TTarget, TType>>;
+    listener: Listener<TTarget, TType>;
     options?: boolean | AddEventListenerOptions;
   },
 ): UnbindFn {

src/types.ts

@@ -31,12 +31,12 @@ type ListenerObject<TEvent extends Event> = {
 };
 
 // event listeners can be an object or a function
-export type Listener<TTarget extends EventTarget, TEvent extends Event> =
-  | ListenerObject<TEvent>
-  | { (this: TTarget, ev: TEvent): void };
+export type Listener<TTarget extends EventTarget, TType extends string = string> =
+  | ListenerObject<InferEvent<TTarget, TType>>
+  | { (this: TTarget, ev: InferEvent<TTarget, TType>): void };
 
 export type Binding<TTarget extends EventTarget = EventTarget, TType extends string = string> = {
   type: TType;
-  listener: Listener<TTarget, InferEvent<TTarget, TType>>;
+  listener: Listener<TTarget, TType>;
   options?: boolean | AddEventListenerOptions;
 };

test/type-tests/bind-all.usage-types.ts

@@ -1,3 +1,4 @@
+import { expectTypeOf } from 'expect-type';
 import { bindAll } from '../../src';
 
 // inline definitions
@@ -23,14 +24,14 @@ import { bindAll } from '../../src';
   bindAll(button, [
     {
       type: 'click',
-      listener(event: MouseEvent) {
-        const value: number = event.button;
+      listener(event) {
+        expectTypeOf(event).toEqualTypeOf<MouseEvent>();
       },
     },
     {
       type: 'keydown',
-      listener(event: KeyboardEvent) {
-        const value: string = event.key;
+      listener(event) {
+        expectTypeOf(event).toEqualTypeOf<KeyboardEvent>();
       },
     },
   ]);

test/type-tests/bind.usage-types.ts

@@ -1,4 +1,5 @@
 import { bind } from '../../src';
+import { expectTypeOf } from 'expect-type';
 
 // inline definitions
 {
@@ -10,14 +11,38 @@ import { bind } from '../../src';
   });
 }
 
+// inline definitions (inferred)
+{
+  const button: HTMLElement = document.createElement('button');
+
+  bind(button, {
+    type: 'keydown',
+    listener(event) {
+      expectTypeOf(event).toEqualTypeOf<KeyboardEvent>();
+    },
+  });
+}
+
+// inline definitions (inferred + no concrete event type)
+{
+  const button: HTMLElement = document.createElement('button');
+
+  bind(button, {
+    type: 'hello',
+    listener(event) {
+      expectTypeOf(event).toEqualTypeOf<Event>();
+    },
+  });
+}
+
 // inferred types
 {
   const button: HTMLElement = document.createElement('button');
 
   bind(button, {
     type: 'click',
     listener(event) {
-      const value: number = event.button;
+      expectTypeOf(event).toEqualTypeOf<MouseEvent>();
     },
   });
 }

yarn.lock

@@ -1261,10 +1261,10 @@ exit@^0.1.2:
   resolved "https://registry.yarnpkg.com/exit/-/exit-0.1.2.tgz#0632638f8d877cc82107d30a0fff1a17cba1cd0c"
   integrity sha1-BjJjj42HfMghB9MKD/8aF8uhzQw=
 
-expect-type@^0.13.0:
-  version "0.13.0"
-  resolved "https://registry.yarnpkg.com/expect-type/-/expect-type-0.13.0.tgz#916646a7a73f3ee77039a634ee9035efe1876eb2"
-  integrity sha512-CclevazQfrqo8EvbLPmP7osnb1SZXkw47XPPvUUpeMz4HuGzDltE7CaIt3RLyT9UQrwVK/LDn+KVcC0hcgjgDg==
+expect-type@^0.15.0:
+  version "0.15.0"
+  resolved "https://registry.yarnpkg.com/expect-type/-/expect-type-0.15.0.tgz#89f75e22c88554844ea2b2faf4ef5fc2e579d3b5"
+  integrity sha512-yWnriYB4e8G54M5/fAFj7rCIBiKs1HAACaY13kCz6Ku0dezjS9aMcfcdVK2X8Tv2tEV1BPz/wKfQ7WA4S/d8aA==
 
 expect@^27.4.6:
   version "27.4.6"