From 62c33147a1f69e1bba727e4ce8436c70e3a15948 Mon Sep 17 00:00:00 2001
From: Cem Staveley <cem.staveley@bbc.co.uk>
Date: Thu, 3 Aug 2017 15:06:37 +0100
Subject: [PATCH] Task: send ceych.errors stats when communicating with the
 cache results in an error

---
 lib/memoize.js      | 11 ++++++++++-
 test/lib/memoize.js | 30 ++++++++++++++++++++++++++----
 2 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/lib/memoize.js b/lib/memoize.js
index 9d750b8..7686fcb 100644
--- a/lib/memoize.js
+++ b/lib/memoize.js
@@ -36,10 +36,16 @@ function registerCallback(promise, cb) {
 }
 
 module.exports = (cacheClient, cacheOpts, fn) => {
+  const statsClient = cacheOpts.statsClient;
+
   function setInCache(key, ttl) {
     return (returnValues) => {
       return cacheClient
         .setAsync(key, returnValues, ttl * 1000)
+        .catch((err) => {
+          statsClient ? statsClient.increment('ceych.errors') : _.noop();
+          return Promise.reject(err);
+        })
         .then(() => returnValues);
     };
   }
@@ -64,7 +70,10 @@ module.exports = (cacheClient, cacheOpts, fn) => {
     }
 
     const reply = cacheClient.getAsync(cacheKey)
-      .catch((err) => Promise.reject(err))
+      .catch((err) => {
+        statsClient ? statsClient.increment('ceych.errors') : _.noop();
+        return Promise.reject(err);
+      })
       .then((cached) => {
         if (cached) {
           statsClient ? statsClient.increment('ceych.hits') : _.noop();
diff --git a/test/lib/memoize.js b/test/lib/memoize.js
index 8df1912..b53f0dc 100644
--- a/test/lib/memoize.js
+++ b/test/lib/memoize.js
@@ -98,8 +98,8 @@ describe('memoize', () => {
       const func = memoize(cacheClient, opts, wrappableWithObject);
 
       return func({
-          testing: '123'
-        })
+        testing: '123'
+      })
         .catch(assert.ifError)
         .then(() => {
           sinon.assert.calledWith(hash.create, `${wrappableWithObject.toString()}[{"testing":"123"}]`);
@@ -234,8 +234,8 @@ describe('memoize', () => {
         const func = memoize(cacheClient, opts, wrappableStub);
 
         return func(1, {
-            two: 'three'
-          }, [4], 'five')
+          two: 'three'
+        }, [4], 'five')
           .catch(assert.ifError)
           .then(() => {
             sinon.assert.calledWith(wrappableStub, 1, sinon.match({
@@ -410,5 +410,27 @@ describe('memoize', () => {
         done();
       });
     });
+
+    it('increments a StatsD counter when fetching from the cache returns an error', (done) => {
+      cacheClient.getAsync.returns(Promise.reject(new Error('error')));
+      const func = memoize(cacheClient, optsWithStats, wrappableWithCb);
+
+      func((err) => {
+        assert.ok(err);
+        sinon.assert.calledWith(statsClient.increment, 'ceych.errors');
+        done();
+      });
+    });
+
+    it('increments a StatsD counter when saving to the cache returns an error', (done) => {
+      cacheClient.setAsync.returns(Promise.reject(new Error('error')));
+      const func = memoize(cacheClient, optsWithStats, wrappableWithCb);
+
+      func((err) => {
+        assert.ok(err);
+        sinon.assert.calledWith(statsClient.increment, 'ceych.errors');
+        done();
+      });
+    });
   });
 });