test: refactor several parallel/test-timer tests

Change var to const/let. Simplify test-timers-uncaught-exception.

PR-URL: #10524
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

test/parallel/test-timers-args.js

@@ -7,7 +7,7 @@ function range(n) {
 }
 
 function timeout(nargs) {
-  var args = range(nargs);
+  const args = range(nargs);
   setTimeout.apply(null, [callback, 1].concat(args));
 
   function callback() {
@@ -17,8 +17,8 @@ function timeout(nargs) {
 }
 
 function interval(nargs) {
-  var args = range(nargs);
-  var timer = setTimeout.apply(null, [callback, 1].concat(args));
+  const args = range(nargs);
+  const timer = setTimeout.apply(null, [callback, 1].concat(args));
 
   function callback() {
     clearInterval(timer);

test/parallel/test-timers-immediate-queue.js

@@ -6,15 +6,13 @@ const assert = require('assert');
 // but immediates queued while processing the current queue should happen
 // on the next turn of the event loop.
 
-// in v0.10 hit should be 1, because we only process one cb per turn
-// in v0.11 and beyond it should be the exact same size of QUEUE
-// if we're letting things recursively add to the immediate QUEUE hit will be
-// > QUEUE
+// hit should be the exact same size of QUEUE, if we're letting things
+// recursively add to the immediate QUEUE hit will be > QUEUE
 
-var ticked = false;
+let ticked = false;
 
-var hit = 0;
-var QUEUE = 1000;
+let hit = 0;
+const QUEUE = 1000;
 
 function run() {
   if (hit === 0)

test/parallel/test-timers-non-integer-delay.js

@@ -1,4 +1,6 @@
 'use strict';
+require('../common');
+
 /*
  * This test makes sure that non-integer timer delays do not make the process
  * hang. See https://github.com/joyent/node/issues/8065 and
@@ -15,13 +17,11 @@
  * it 100%.
  */
 
-require('../common');
-
-var TIMEOUT_DELAY = 1.1;
-var NB_TIMEOUTS_FIRED = 50;
+const TIMEOUT_DELAY = 1.1;
+const NB_TIMEOUTS_FIRED = 50;
 
-var nbTimeoutFired = 0;
-var interval = setInterval(function() {
+let nbTimeoutFired = 0;
+const interval = setInterval(function() {
   ++nbTimeoutFired;
   if (nbTimeoutFired === NB_TIMEOUTS_FIRED) {
     clearInterval(interval);

test/parallel/test-timers-ordering.js

@@ -1,22 +1,22 @@
 'use strict';
 require('../common');
 const assert = require('assert');
-var Timer = process.binding('timer_wrap').Timer;
 
-var N = 30;
+const Timer = process.binding('timer_wrap').Timer;
+const N = 30;
 
-var last_i = 0;
-var last_ts = 0;
+let last_i = 0;
+let last_ts = 0;
 
-var f = function(i) {
+const f = function(i) {
   if (i <= N) {
     // check order
-    assert.equal(i, last_i + 1, 'order is broken: ' + i + ' != ' +
+    assert.strictEqual(i, last_i + 1, 'order is broken: ' + i + ' != ' +
                  last_i + ' + 1');
     last_i = i;
 
     // check that this iteration is fired at least 1ms later than the previous
-    var now = Timer.now();
+    const now = Timer.now();
     console.log(i, now);
     assert(now >= last_ts + 1,
            'current ts ' + now + ' < prev ts ' + last_ts + ' + 1');

test/parallel/test-timers-uncaught-exception.js

@@ -1,40 +1,18 @@
 'use strict';
-require('../common');
+const common = require('../common');
 const assert = require('assert');
-
-var exceptions = 0;
-var timer1 = 0;
-var timer2 = 0;
+const errorMsg = 'BAM!';
 
 // the first timer throws...
-console.error('set first timer');
-setTimeout(function() {
-  console.error('first timer');
-  timer1++;
-  throw new Error('BAM!');
-}, 100);
+setTimeout(common.mustCall(function() {
+  throw new Error(errorMsg);
+}), 1);
 
 // ...but the second one should still run
-console.error('set second timer');
-setTimeout(function() {
-  console.error('second timer');
-  assert.equal(timer1, 1);
-  timer2++;
-}, 100);
+setTimeout(common.mustCall(function() {}), 1);
 
 function uncaughtException(err) {
-  console.error('uncaught handler');
-  assert.equal(err.message, 'BAM!');
-  exceptions++;
+  assert.strictEqual(err.message, errorMsg);
 }
-process.on('uncaughtException', uncaughtException);
 
-var exited = false;
-process.on('exit', function() {
-  assert(!exited);
-  exited = true;
-  process.removeListener('uncaughtException', uncaughtException);
-  assert.equal(exceptions, 1);
-  assert.equal(timer1, 1);
-  assert.equal(timer2, 1);
-});
+process.on('uncaughtException', common.mustCall(uncaughtException));