feat: add test for catching errors in Emitter

Author: jsjoeio

test/emitter.test.ts

@@ -1,7 +1,25 @@
+// Note: we need to import logger from the root
+// because this is the logger used in logError in ../src/common/util
+import { logger } from "../node_modules/@coder/logger"
+
 import { Emitter } from "../src/common/emitter"
 
 describe("emitter", () => {
   describe("Emitter", () => {
+    let spy: jest.SpyInstance
+
+    beforeEach(() => {
+      spy = jest.spyOn(logger, "error")
+    })
+
+    afterEach(() => {
+      jest.clearAllMocks()
+    })
+
+    afterAll(() => {
+      jest.restoreAllMocks()
+    })
+
     it("should return an Emitter", async () => {
       const HELLO_WORLD = "HELLO_WORLD"
       const GOODBYE_WORLD = "GOODBYE_WORLD"
@@ -43,10 +61,28 @@ describe("emitter", () => {
       emitter.dispose()
     })
 
-    it.skip("should log an error if something goes wrong", () => {
-      // not sure how we're going to test this
-      // need to mock logger
-      // and then somehow throw or something in the callback
+    it("should log an error if something goes wrong", async () => {
+      const HELLO_WORLD = "HELLO_WORLD"
+      const mockCallback = jest.fn(() => "Mock function called")
+      const message = "You don't have access to that folder."
+
+      const emitter = new Emitter<{ event: string; callback: () => void }>()
+
+      const onHelloWorld = ({ event, callback }: { event: string; callback: () => void }): void => {
+        if (event === HELLO_WORLD) {
+          callback()
+          throw new Error(message)
+        }
+      }
+
+      emitter.event(onHelloWorld)
+
+      await emitter.emit({ event: HELLO_WORLD, callback: mockCallback })
+
+      // Check that error was called
+      expect(spy).toHaveBeenCalled()
+      expect(spy).toHaveBeenCalledTimes(1)
+      expect(spy).toHaveBeenCalledWith(message)
     })
   })
 })