tests(types): add createEventBus compile time type checks test

added expect-type which is jest like compile time type checks test framework
added coverage for createEventBus return type check to prevent type regression
in the futur

package.json

@@ -45,6 +45,7 @@
     "@types/chrome": "^0.0.155",
     "@types/jest": "^26.0.20",
     "@types/ws": "^3.2.1",
+    "expect-type": "^0.13.0",
     "husky": "^4.3.8",
     "jest": "^28.1.3",
     "npm-run-all": "^4.1.5",

test/Types.spec.ts

@@ -0,0 +1,32 @@
+import { expectTypeOf } from 'expect-type'
+import { createEventBus } from '../src/Events'
+import { Slot, slot } from '../src/Slot'
+
+describe('createEventBus', () => {
+    type Events = {
+        numberToString: Slot<number, string>
+        eventToIgnore: Slot<void, void>
+    }
+
+    type FilteredEvents = {
+        numberToString: Slot<number, string>
+    }
+
+    const events: Events = {
+        numberToString: slot<number, string>(),
+        eventToIgnore: slot<void, void>(),
+    }
+
+    it('should return the right types regardless of an ingnoredEvents list being passed or not', () => {
+        const eventBus = createEventBus({ events })
+        const eventBusWithIgnored = createEventBus({
+            events,
+            ignoredEvents: ['eventToIgnore'],
+        })
+
+        expectTypeOf(eventBus).toEqualTypeOf<Events>()
+        expectTypeOf(eventBus).not.toEqualTypeOf<FilteredEvents>()
+        expectTypeOf(eventBusWithIgnored).not.toEqualTypeOf<Events>()
+        expectTypeOf(eventBusWithIgnored).toEqualTypeOf<FilteredEvents>()
+    })
+})

yarn.lock

@@ -2091,6 +2091,11 @@ 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@^28.1.3:
   version "28.1.3"
   resolved "https://registry.yarnpkg.com/expect/-/expect-28.1.3.tgz#90a7c1a124f1824133dd4533cce2d2bdcb6603ec"