Update tests to properly terminate (#255)

Which problem is this PR solving?
Cleans up two tests so that jest doesn't complain that some tests were failing to close sockets
Short description of the changes
Destroy a socket rather than close it because the socket was waiting for an acknowledgement that would never come
Adjust timeout so that server closes before jest gets bored
Call done() from within close() so that it has time to close.
Note that the standard formatting has changed a bit in the last 4 years, so this includes some whitespace changes due to eslint.

@jessitron contributed a lot to figuring this out.

src/__tests__/transmission_test.js

@@ -17,11 +17,15 @@ describe("base transmission", () => {
     mock.unmock(superagent);
   });
 
+  // This checks that the code connects to a proxy
   it("will hit a proxy", done => {
     let server = net.createServer(socket => {
-      socket.end();
-      server.close();
-      done();
+      // if we get here, we got data, so the test passes -- otherwise,
+      // the test will never end and will timeout, which is a failure.
+      socket.destroy();
+      server.close(() => {
+        done();
+      });
     });
 
     server.listen(9998, "127.0.0.1");
@@ -90,9 +94,9 @@ describe("base transmission", () => {
         return responseCount === batchSize
           ? done()
           : done(
-              "The events dispatched over transmission does not align with batch size when the same number of " +
-                `events were enqueued as the batchSizeTrigger. Expected ${batchSize}, got ${responseCount}.`
-            );
+            "The events dispatched over transmission does not align with batch size when the same number of " +
+            `events were enqueued as the batchSizeTrigger. Expected ${batchSize}, got ${responseCount}.`
+          );
       }
     });
 
@@ -121,7 +125,7 @@ describe("base transmission", () => {
 
     let transmission = new Transmission({
       batchTimeTrigger: 0,
-      responseCallback: function(_resp) {
+      responseCallback: function (_resp) {
         expect(endpointHit).toBe(true);
         done();
       }
@@ -142,7 +146,7 @@ describe("base transmission", () => {
   it("should eventually send a single event (after the timeout)", done => {
     let transmission = new Transmission({
       batchTimeTrigger: 10,
-      responseCallback: function(_resp) {
+      responseCallback: function (_resp) {
         done();
       }
     });
@@ -162,12 +166,12 @@ describe("base transmission", () => {
   it("should respect sample rate and accept the event", done => {
     let transmission = new Transmission({
       batchTimeTrigger: 10,
-      responseCallback: function(_resp) {
+      responseCallback: function (_resp) {
         done();
       }
     });
 
-    transmission._randomFn = function() {
+    transmission._randomFn = function () {
       return 0.09;
     };
     transmission.sendEvent(
@@ -185,10 +189,10 @@ describe("base transmission", () => {
   it("should respect sample rate and drop the event", done => {
     let transmission = new Transmission({ batchTimeTrigger: 10 });
 
-    transmission._randomFn = function() {
+    transmission._randomFn = function () {
       return 0.11;
     };
-    transmission._droppedCallback = function() {
+    transmission._droppedCallback = function () {
       done();
     };
 
@@ -228,7 +232,7 @@ describe("base transmission", () => {
       }
     });
 
-    transmission._droppedCallback = function() {
+    transmission._droppedCallback = function () {
       eventDropped = true;
     };
 
@@ -432,10 +436,10 @@ describe("base transmission", () => {
         return responseCount === responseExpected
           ? done()
           : done(
-              Error(
-                "Incorrect queue length. Queue should equal length of all valid and invalid events enqueued."
-              )
-            );
+            Error(
+              "Incorrect queue length. Queue should equal length of all valid and invalid events enqueued."
+            )
+          );
       }
     });
 
@@ -617,48 +621,39 @@ describe("base transmission", () => {
     // we can't use superagent-mocker here, since we want the request to timeout,
     // and there's no async flow in -mocker :(
 
+    // This number needs to be less than the global test timeout of 5000 so that the server closes in time
+    // before jest starts complaining.
+    const serverTimeout = 2500; // milliseconds
+
     const server = http.createServer((req, res) => {
       setTimeout(
         () => {
           // this part doesn't really matter
           res.writeHead(200, { "Content-Type": "application/json" });
           res.end("[{ status: 666 }]");
         },
-        // because this number is longer than our 5000 global test timeout, as well as (more importantly)
-        // the `timeout: 2000` below.
-        7500
+        serverTimeout
       );
     });
     server.listen(6666, "localhost", () => {
+      let errResult;
       let transmission = new Transmission({
         batchTimeTrigger: 10,
-        timeout: 2000,
-        responseCallback: function(respQueue) {
-          server.close();
-
+        timeout: serverTimeout - 500,
+        responseCallback: async function (respQueue) {
           if (respQueue.length !== 1) {
-            done(
-              new Error(
-                `expected response queue length = 1, got ${respQueue.length}`
-              )
-            );
-            return;
+            errResult = new Error(`expected response queue length = 1, got ${respQueue.length}`);
           }
 
           const resp = respQueue[0];
 
-          if (resp.error && resp.error.timeout) {
-            done();
-            return;
+          if (!(resp.error && resp.error.timeout)) {
+            errResult = new Error(`expected a timeout error, instead got ${JSON.stringify(resp.error)}`);
           }
 
-          done(
-            new Error(
-              `expected a timeout error, instead got ${JSON.stringify(
-                resp.error
-              )}`
-            )
-          );
+          server.close(() => {
+            done(errResult);
+          });
         }
       });