Add test coverage for ExportUsers class

.babelrc

@@ -4,5 +4,10 @@
   }]],
   "presets": [
     "@babel/preset-env"
-  ]
+  ],
+  "env": {
+    "test": {
+      "plugins": ["@babel/plugin-transform-runtime"]
+    }
+  }
 }

__mocks__/cognito-fake.js

@@ -0,0 +1,18 @@
+export default class CognitoFake {
+  listUsers() {
+    return {
+      promise: async () => {
+        return new Promise(resolve => {
+          return resolve(
+            {
+              Users: [
+                { Username: 'user1' },
+                { Username: 'user2' }
+              ]
+            }
+          )
+        })
+      }
+    }
+  }
+}

__mocks__/cognito-pagination-fake.js

@@ -0,0 +1,33 @@
+export default class CognitoPaginationFake {
+  constructor() {
+    this.calledAlready = false
+  }
+
+  listUsers() {
+    return {
+      promise: async () => {
+        return new Promise(resolve => {
+          if (this.calledAlready) {
+            return resolve(
+              {
+                Users: [
+                  { Username: 'user2' }
+                ]
+              }
+            )
+          } else {
+            this.calledAlready= true
+            return resolve(
+              {
+                Users: [
+                  { Username: 'user1' }
+                ],
+                PaginationToken: 'token'
+              }
+            )
+          }
+        })
+      }
+    }
+  }
+}

__tests__/ExportUsers.test.js

@@ -1,5 +1,51 @@
+import AWS from 'aws-sdk'
+import ExportUsers from '../src/ExportUsers'
+import CognitoFake from '../__mocks__/cognito-fake'
+import CognitoPaginationFake from '../__mocks__/cognito-pagination-fake'
+
 describe('ExportUsers', () => {
-  test('dummy test', () => {
-    expect(true).toEqual(true)
+  const exporter = new ExportUsers()
+
+  describe('constructor()', () => {
+    it('sets cognito', () => {
+      expect(exporter.cognito).toBeInstanceOf(AWS.CognitoIdentityServiceProvider)
+    })
+  })
+
+  describe('export()', () => {
+    const logSpy = jest.spyOn(console, 'log')
+
+    describe('without pagination', () => {
+      beforeAll(() => {
+        exporter.cognito = new CognitoFake()
+      })
+
+      it('logs a message', async () => {
+        await exporter.export()
+        expect(logSpy).toHaveBeenCalledWith('Users exported from Cognito')
+      })
+
+      it('returns a list of users', async () => {
+        const userList = await exporter.export()
+        expect(userList).toEqual([{"Username":"user1"},{"Username":"user2"}])
+      })
+    })
+
+    describe('with pagination', () => {
+      // NOTE: Using beforeEach instead of beforeAll because the pagination fake stores the state of whether listUsers() has been called already
+      beforeEach(() => {
+        exporter.cognito = new CognitoPaginationFake()
+      })
+
+      it('logs a message', async () => {
+        await exporter.export()
+        expect(logSpy).toHaveBeenCalledWith('Users exported from Cognito')
+      })
+
+      it('returns a list of users', async () => {
+        const userList = await exporter.export()
+        expect(userList).toEqual([{"Username":"user1"},{"Username":"user2"}])
+      })
+    })
   })
 })

package.json

@@ -38,6 +38,7 @@
     }
   ],
   "devDependencies": {
+    "@babel/plugin-transform-runtime": "^7.4.4",
     "babel-eslint": "^10.0.1",
     "eslint": "^5.16.0",
     "eslint-plugin-import": "^2.17.2",

src/ExportUsers.js

@@ -13,11 +13,12 @@ export default class ExportUsers {
 
     const paginationCalls = async (exportedUsers = []) => {
       const { Users = [], PaginationToken } = await this.cognito.listUsers(params).promise()
+
       const combinedUsers = exportedUsers.concat(Users)
 
       if (PaginationToken) {
         params.PaginationToken = PaginationToken
-        await paginationCalls(combinedUsers)
+        return await paginationCalls(combinedUsers)
       }
 
       return combinedUsers