adding in tests to test the emit with latency

test/test.js

@@ -668,6 +668,40 @@ test('rolling percentile enabled option set to false', (t) => {
   t.end();
 });
 
+test('Circuit Breaker success event emits latency', (t) => {
+  t.plan(1);
+  const breaker = cb(passFail);
+  breaker.on('success', (result, latencyTime) => {
+    t.ok(latencyTime, 'second argument is the latency');
+    t.end();
+  });
+
+  breaker.fire(1);
+});
+
+test('Circuit Breaker timeout event emits latency', (t) => {
+  t.plan(1);
+  const breaker = cb(passFail);
+  breaker.on('failure', (result, latencyTime) => {
+    t.ok(latencyTime, 'second argument is the latency');
+    t.end();
+  });
+
+  breaker.fire(-1).catch(() => {});
+});
+
+test('Circuit Breaker failure event emits latency', (t) => {
+  t.plan(1);
+  const breaker = cb(slowFunction, { timeout: 10 });
+
+  breaker.on('timeout', (result, latencyTime) => {
+    t.ok(latencyTime, 'second argument is the latency');
+    t.end();
+  });
+
+  breaker.fire(-1).catch(() => {});
+});
+
 /**
  * Returns a promise that resolves if the parameter
  * 'x' evaluates to >= 0. Otherwise the returned promise fails.