replaced get/put fn expressions with arrow functions

Author: emilygilberts

tests/unit/test.mapreduce.js

@@ -9,9 +9,7 @@ describe('test.mapreduce.js-upsert', function () {
   it('should throw an error if the doc errors', async function () {
     try {
       await upsert({
-        get: function () {
-          return Promise.reject(new Error('a fake error!'));
-        },
+        get: () => Promise.reject(new Error('a fake error!')),
       }, 'foo');
 
       should.fail("Expected promise to be rejected");
@@ -22,9 +20,7 @@ describe('test.mapreduce.js-upsert', function () {
 
   it('should fulfill if the diff returns false', async function () {
     const res = await upsert({
-      get: function () {
-        return Promise.resolve({ _rev: 'xyz' });
-      },
+      get: () => Promise.resolve({ _rev: 'xyz' }),
     }, 'foo', function () {
       return false;
     });
@@ -35,12 +31,8 @@ describe('test.mapreduce.js-upsert', function () {
 
   it('should put if get throws 404', async function () {
     const res = await upsert({
-      get: function () {
-        return Promise.reject({ status: 404 });
-      },
-      put: function () {
-        return Promise.resolve({ rev: 'abc' });
-      },
+      get: () => Promise.reject({ status: 404 }),
+      put: () => Promise.resolve({ rev: 'abc' }),
     }, 'foo', function () {
       return { difference: "something" };
     });
@@ -52,14 +44,10 @@ describe('test.mapreduce.js-upsert', function () {
   it('should error if it can\'t put', async function () {
     try {
       await upsert({
-        get: function () {
-          return Promise.resolve({ _rev: 'xyz' });
-        },
-        put: function () {
-          return Promise.reject(new Error('falala'));
-        },
+        get: () => Promise.resolve({ _rev: 'xyz' }),
+        put: () => Promise.reject(new Error('falala')),
       }, 'foo', function () {
-          return { difference: "something" };
+        return { difference: "something" };
       });
 
       should.fail("Expected promise to be rejected");