Handle null transmission in flush (#253)

* Update libhoney.js
* Add support for async tests
* Add test for flush

package.json

@@ -45,6 +45,7 @@
     "jest": "^27.2.4",
     "jest-in-case": "^1.0.2",
     "prettier": "^2.3.1",
+    "regenerator-runtime": "^0.13.9",
     "rollup": "^2.58.0",
     "superagent-mocker": "^0.5.2"
   },
@@ -57,6 +58,9 @@
     "https-proxy-agent": "^3.0.0"
   },
   "jest": {
+    "setupFilesAfterEnv": [
+      "./setupTests.js"
+    ],
     "testPathIgnorePatterns": [
       "dist/",
       "/node_modules/"

setupTests.js

@@ -0,0 +1 @@
+import "regenerator-runtime/runtime";

src/__tests__/libhoney_test.js

@@ -154,7 +154,7 @@ describe("libhoney", () => {
   });
 
   describe("disabled = true", () => {
-    it("should not hit transmission", () => {
+    it("should not hit transmission", async () => {
       let honey = new libhoney({
         // these two properties are required
         writeKey: "12345",
@@ -165,6 +165,7 @@ describe("libhoney", () => {
       let transmission = honey.transmission;
 
       expect(transmission).toBe(null);
+      await expect(honey.flush()).resolves.toBeUndefined();
     });
   });
 });

src/libhoney.js

@@ -457,6 +457,10 @@ export default class Libhoney extends EventEmitter {
       this._options
     );
 
+    if (!transmission) {
+      return Promise.resolve();
+    }
+
     return transmission.flush();
   }
 }