From 0136cd12c71caa4eb53d2c0644c7dcf693b5064b Mon Sep 17 00:00:00 2001
From: emadum <eric.adum@mongodb.com>
Date: Wed, 6 May 2020 16:00:17 -0400
Subject: [PATCH 01/10] add test and fix

---
 lib/operations/connect.js          | 12 ++++++++++++
 package.json                       |  2 +-
 test/functional/connection.test.js | 30 +++++++++++++++++++++++++++---
 test/functional/shared.js          | 13 ++++++++++++-
 4 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/lib/operations/connect.js b/lib/operations/connect.js
index 7378367b4a0..08a69d291e4 100644
--- a/lib/operations/connect.js
+++ b/lib/operations/connect.js
@@ -260,6 +260,18 @@ function connect(mongoClient, url, options, callback) {
     throw new Error('no callback function provided');
   }
 
+  // Has a connection already been established?
+  if (mongoClient.topology) {
+    if (mongoClient.topology.isConnected()) {
+      throw new Error('already connected');
+    }
+    // this is a reconnect, clear out old state
+    mongoClient.topology = undefined;
+    mongoClient.s.options = {};
+    mongoClient.s.dbCache = new Map();
+    mongoClient.s.sessions = new Set();
+  }
+
   let didRequestAuthentication = false;
   const logger = Logger('MongoClient', options);
 
diff --git a/package.json b/package.json
index 56e7576de74..1ef4959cb55 100644
--- a/package.json
+++ b/package.json
@@ -68,7 +68,7 @@
     "test": "npm run lint && mocha --recursive test/functional test/unit test/core",
     "test-nolint": "mocha --recursive test/functional test/unit test/core",
     "coverage": "istanbul cover mongodb-test-runner -- -t 60000 test/core test/unit test/functional",
-    "lint": "eslint lib test",
+    "lint": "eslint -v && eslint lib test",
     "format": "prettier --print-width 100 --tab-width 2 --single-quote --write 'test/**/*.js' 'lib/**/*.js'",
     "bench": "node test/benchmarks/driverBench/",
     "generate-evergreen": "node .evergreen/generate_evergreen_tasks.js",
diff --git a/test/functional/connection.test.js b/test/functional/connection.test.js
index a75916eeb6f..f4a9ade250f 100644
--- a/test/functional/connection.test.js
+++ b/test/functional/connection.test.js
@@ -1,7 +1,8 @@
 'use strict';
-const test = require('./shared').assert,
-  setupDatabase = require('./shared').setupDatabase,
-  expect = require('chai').expect;
+const test = require('./shared').assert;
+const setupDatabase = require('./shared').setupDatabase;
+const withClient = require('./shared').withClient;
+const expect = require('chai').expect;
 
 describe('Connection', function() {
   before(function() {
@@ -514,4 +515,27 @@ describe('Connection', function() {
       });
     }
   });
+
+  it('should be able to connect again after close', function() {
+    return withClient(this.configuration.newClient(), client => done => {
+      expect(client.isConnected()).to.be.true;
+      const collection = () => client.db('testReconnect').collection('test');
+      collection().insertOne({ a: 1 }, (err, result) => {
+        expect(err).to.not.exist;
+        expect(result).to.exist;
+        client.close(err => {
+          expect(err).to.not.exist;
+          client.connect(err => {
+            expect(err).to.not.exist;
+            collection().insertOne({ b: 2 }, (err, result) => {
+              expect(err).to.not.exist;
+              expect(result).to.exist;
+              expect(client.topology.isDestroyed()).to.be.false;
+              done();
+            });
+          });
+        });
+      });
+    });
+  });
 });
diff --git a/test/functional/shared.js b/test/functional/shared.js
index 65023355140..d3c59094517 100644
--- a/test/functional/shared.js
+++ b/test/functional/shared.js
@@ -78,9 +78,20 @@ function makeCleanupFn(client) {
 function withClient(client, operation, errorHandler) {
   const cleanup = makeCleanupFn(client);
 
+  function operationHandler(client) {
+    // run the operation
+    const result = operation(client);
+    // if it returns a callback, wrap it in a Promise
+    if (typeof result === 'function') {
+      return new Promise(done => result(done));
+    }
+    // otherwise assume it returned a Promise
+    return result;
+  }
+
   return client
     .connect()
-    .then(operation, errorHandler)
+    .then(operationHandler, errorHandler)
     .then(() => cleanup(), cleanup);
 }
 

From 3be1b95cf432f62774016ef46e5051bdc6ea8aa4 Mon Sep 17 00:00:00 2001
From: emadum <eric.adum@mongodb.com>
Date: Fri, 8 May 2020 09:32:51 -0400
Subject: [PATCH 02/10] clean up evg logs

---
 .evergreen/install-dependencies.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.evergreen/install-dependencies.sh b/.evergreen/install-dependencies.sh
index acfd7f2fe11..d2edf9b8e83 100644
--- a/.evergreen/install-dependencies.sh
+++ b/.evergreen/install-dependencies.sh
@@ -18,7 +18,7 @@ mkdir -p "${NPM_TMP_DIR}"
 # install Node.js
 curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.8/install.sh | bash
 [ -s "${NVM_DIR}/nvm.sh" ] && \. "${NVM_DIR}/nvm.sh"
-nvm install --lts=${NODE_LTS_NAME}
+nvm install --no-progress --lts=${NODE_LTS_NAME}
 
 # setup npm cache in a local directory
 cat <<EOT > .npmrc

From 865d8b597d892a693dc41324e2eb56d96bf4b827 Mon Sep 17 00:00:00 2001
From: emadum <eric.adum@mongodb.com>
Date: Fri, 8 May 2020 09:46:11 -0400
Subject: [PATCH 03/10] update nvm to support --no-progress

---
 .evergreen/install-dependencies.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.evergreen/install-dependencies.sh b/.evergreen/install-dependencies.sh
index d2edf9b8e83..29ee53841cb 100644
--- a/.evergreen/install-dependencies.sh
+++ b/.evergreen/install-dependencies.sh
@@ -16,7 +16,7 @@ mkdir -p ${NPM_CACHE_DIR}
 mkdir -p "${NPM_TMP_DIR}"
 
 # install Node.js
-curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.8/install.sh | bash
+curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.35.3/install.sh | bash
 [ -s "${NVM_DIR}/nvm.sh" ] && \. "${NVM_DIR}/nvm.sh"
 nvm install --no-progress --lts=${NODE_LTS_NAME}
 

From 854c72f1129c2124a2f599632b02e91d91c56191 Mon Sep 17 00:00:00 2001
From: emadum <eric.adum@mongodb.com>
Date: Fri, 8 May 2020 09:53:58 -0400
Subject: [PATCH 04/10] add XFG_CONFIG_HOME for new nvm

---
 .evergreen/install-dependencies.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.evergreen/install-dependencies.sh b/.evergreen/install-dependencies.sh
index 29ee53841cb..e856ee76f48 100644
--- a/.evergreen/install-dependencies.sh
+++ b/.evergreen/install-dependencies.sh
@@ -9,6 +9,7 @@ NPM_TMP_DIR="${NODE_ARTIFACTS_PATH}/tmp"
 
 # this needs to be explicitly exported for the nvm install below
 export NVM_DIR="${NODE_ARTIFACTS_PATH}/nvm"
+export XDG_CONFIG_HOME=${NODE_ARTIFACTS_PATH}
 
 # create node artifacts path if needed
 mkdir -p ${NODE_ARTIFACTS_PATH}

From 5043ca3f6d8c4a8751c5aed5045bfdb85c130925 Mon Sep 17 00:00:00 2001
From: emadum <eric.adum@mongodb.com>
Date: Mon, 11 May 2020 09:45:01 -0400
Subject: [PATCH 05/10] incorporate review feedback

---
 lib/mongo_client.js                | 27 ++++++++-----
 lib/operations/connect.js          | 11 +-----
 test/functional/connection.test.js |  2 +-
 test/functional/shared.js          | 61 ++++++++++++++++--------------
 4 files changed, 53 insertions(+), 48 deletions(-)

diff --git a/lib/mongo_client.js b/lib/mongo_client.js
index 2d58247788b..8be08637778 100644
--- a/lib/mongo_client.js
+++ b/lib/mongo_client.js
@@ -167,6 +167,8 @@ function MongoClient(url, options) {
     writeConcern: WriteConcern.fromOptions(options),
     namespace: new MongoDBNamespace('admin')
   };
+
+  this.originalOptions = Object.assign({}, this.s.options);
 }
 
 /**
@@ -241,28 +243,35 @@ MongoClient.prototype.close = function(force, callback) {
     force = false;
   }
 
-  const client = this;
   return maybePromise(this, callback, cb => {
     const completeClose = err => {
-      client.emit('close', client);
+      this.emit('close', this);
 
-      if (!(client.topology instanceof NativeTopology)) {
-        for (const item of client.s.dbCache) {
-          item[1].emit('close', client);
+      if (!(this.topology instanceof NativeTopology)) {
+        for (const item of this.s.dbCache) {
+          item[1].emit('close', this);
         }
       }
 
-      client.removeAllListeners('close');
+      this.removeAllListeners('close');
+
+      // clear out references to old topology
+      this.topology = undefined;
+      this.s.dbCache = new Map();
+
+      // restore options
+      this.s.options = Object.assign({}, this.originalOptions);
+
       cb(err);
     };
 
-    if (client.topology == null) {
+    if (this.topology == null) {
       completeClose();
       return;
     }
 
-    client.topology.close(force, err => {
-      const autoEncrypter = client.topology.s.options.autoEncrypter;
+    this.topology.close(force, err => {
+      const autoEncrypter = this.topology.s.options.autoEncrypter;
       if (!autoEncrypter) {
         completeClose(err);
         return;
diff --git a/lib/operations/connect.js b/lib/operations/connect.js
index 08a69d291e4..5d5c2ba3b25 100644
--- a/lib/operations/connect.js
+++ b/lib/operations/connect.js
@@ -261,15 +261,8 @@ function connect(mongoClient, url, options, callback) {
   }
 
   // Has a connection already been established?
-  if (mongoClient.topology) {
-    if (mongoClient.topology.isConnected()) {
-      throw new Error('already connected');
-    }
-    // this is a reconnect, clear out old state
-    mongoClient.topology = undefined;
-    mongoClient.s.options = {};
-    mongoClient.s.dbCache = new Map();
-    mongoClient.s.sessions = new Set();
+  if (mongoClient.topology && mongoClient.topology.isConnected()) {
+    throw new Error(`'connect' cannot be called when already connected`);
   }
 
   let didRequestAuthentication = false;
diff --git a/test/functional/connection.test.js b/test/functional/connection.test.js
index f4a9ade250f..a4ce997d64f 100644
--- a/test/functional/connection.test.js
+++ b/test/functional/connection.test.js
@@ -517,7 +517,7 @@ describe('Connection', function() {
   });
 
   it('should be able to connect again after close', function() {
-    return withClient(this.configuration.newClient(), client => done => {
+    return withClient.call(this, (client, done) => {
       expect(client.isConnected()).to.be.true;
       const collection = () => client.db('testReconnect').collection('test');
       collection().insertOne({ a: 1 }, (err, result) => {
diff --git a/test/functional/shared.js b/test/functional/shared.js
index 85e07f54e11..79443b59a7f 100644
--- a/test/functional/shared.js
+++ b/test/functional/shared.js
@@ -57,8 +57,37 @@ function setupDatabase(configuration, dbsToClean) {
     );
 }
 
-function makeCleanupFn(client) {
-  return function(err) {
+function withTempDb(name, options, client, operation, errorHandler) {
+  return withClient(
+    client,
+    client => done => {
+      const db = client.db(name, options);
+      operation.call(this, db)(() => db.dropDatabase(done));
+    },
+    errorHandler
+  );
+}
+
+/**
+ * Safely perform a test with provided MongoClient, ensuring client won't leak.
+ *
+ * @param {MongoClient} [client] if not provided, withClient must be bound to test function `this`
+ * @param {Function} operation (client):Promise or (client, done):void
+ * @param {Function} [errorHandler]
+ */
+function withClient(client, operation, errorHandler) {
+  if (!(client instanceof MongoClient)) {
+    errorHandler = operation;
+    operation = client;
+    client = this.configuration.newClient();
+  }
+
+  if (operation.length === 2) {
+    const callback = operation;
+    operation = client => new Promise(resolve => callback(client, resolve));
+  }
+
+  function cleanup(err) {
     return new Promise((resolve, reject) => {
       try {
         client.close(closeErr => {
@@ -72,37 +101,11 @@ function makeCleanupFn(client) {
         return reject(err || e);
       }
     });
-  };
-}
-
-function withTempDb(name, options, client, operation, errorHandler) {
-  return withClient(
-    client,
-    client => done => {
-      const db = client.db(name, options);
-      operation.call(this, db)(() => db.dropDatabase(done));
-    },
-    errorHandler
-  );
-}
-
-function withClient(client, operation, errorHandler) {
-  const cleanup = makeCleanupFn(client);
-
-  function operationHandler(client) {
-    // run the operation
-    const result = operation(client);
-    // if it returns a callback, wrap it in a Promise
-    if (typeof result === 'function') {
-      return new Promise(done => result(done));
-    }
-    // otherwise assume it returned a Promise
-    return result;
   }
 
   return client
     .connect()
-    .then(operationHandler, errorHandler)
+    .then(operation, errorHandler)
     .then(() => cleanup(), cleanup);
 }
 

From 5763728f310129a6095702ae5081c5f1e171bb93 Mon Sep 17 00:00:00 2001
From: emadum <eric.adum@mongodb.com>
Date: Mon, 11 May 2020 09:59:28 -0400
Subject: [PATCH 06/10] refactor withTempDb to withDb

---
 test/functional/change_stream.test.js | 38 +++++++++++++--------------
 test/functional/shared.js             | 28 +++++++++++++-------
 2 files changed, 38 insertions(+), 28 deletions(-)

diff --git a/test/functional/change_stream.test.js b/test/functional/change_stream.test.js
index 020de3d6c44..f8ad85a1273 100644
--- a/test/functional/change_stream.test.js
+++ b/test/functional/change_stream.test.js
@@ -4,7 +4,8 @@ var Transform = require('stream').Transform;
 const MongoError = require('../../lib/core').MongoError;
 var MongoNetworkError = require('../../lib/core').MongoNetworkError;
 var setupDatabase = require('./shared').setupDatabase;
-var withTempDb = require('./shared').withTempDb;
+var withClient = require('./shared').withClient;
+var withDb = require('./shared').withDb;
 var delay = require('./shared').delay;
 var co = require('co');
 var mock = require('mongodb-mock-server');
@@ -2635,19 +2636,21 @@ describe('Change Streams', function() {
     it('should return null on single iteration of empty cursor', {
       metadata: { requires: { topology: 'replicaset', mongodb: '>=3.6' } },
       test: function() {
-        return withTempDb(
-          'testTryNext',
-          { w: 'majority' },
-          this.configuration.newClient(),
-          db => done => {
-            const changeStream = db.collection('test').watch();
-            tryNext(changeStream, (err, doc) => {
-              expect(err).to.not.exist;
-              expect(doc).to.not.exist;
+        return withClient.bind(this)(
+          withDb(
+            'testTryNext',
+            { w: 'majority' },
+            (db, done) => {
+              const changeStream = db.collection('test').watch();
+              tryNext(changeStream, (err, doc) => {
+                expect(err).to.not.exist;
+                expect(doc).to.not.exist;
 
-              changeStream.close(done);
-            });
-          }
+                changeStream.close(done);
+              });
+            },
+            true
+          )
         );
       }
     });
@@ -2655,11 +2658,8 @@ describe('Change Streams', function() {
     it('should iterate a change stream until first empty batch', {
       metadata: { requires: { topology: 'replicaset', mongodb: '>=3.6' } },
       test: function() {
-        return withTempDb(
-          'testTryNext',
-          { w: 'majority' },
-          this.configuration.newClient(),
-          db => done => {
+        return withClient.bind(this)(
+          withDb('testTryNext', { w: 'majority' }, (db, done) => {
             const collection = db.collection('test');
             const changeStream = collection.watch();
             waitForStarted(changeStream, () => {
@@ -2688,7 +2688,7 @@ describe('Change Streams', function() {
                 });
               });
             });
-          }
+          })
         );
       }
     });
diff --git a/test/functional/shared.js b/test/functional/shared.js
index 79443b59a7f..24906972ec8 100644
--- a/test/functional/shared.js
+++ b/test/functional/shared.js
@@ -57,15 +57,25 @@ function setupDatabase(configuration, dbsToClean) {
     );
 }
 
-function withTempDb(name, options, client, operation, errorHandler) {
-  return withClient(
-    client,
-    client => done => {
+/**
+ * use as the `operation` of `withClient`
+ *
+ * @param {string} name database name
+ * @param {object} [options] database options
+ * @param {Function} testFn test function to execute
+ * @param {boolean} [drop] drop database after test
+ */
+function withDb(name, options, testFn, drop) {
+  if (typeof options === 'function') {
+    drop = testFn;
+    testFn = options;
+    options = {};
+  }
+  return client =>
+    new Promise(resolve => {
       const db = client.db(name, options);
-      operation.call(this, db)(() => db.dropDatabase(done));
-    },
-    errorHandler
-  );
+      testFn(db, drop ? () => db.dropDatabase(resolve) : resolve);
+    });
 }
 
 /**
@@ -243,7 +253,7 @@ module.exports = {
   delay,
   withClient,
   withMonitoredClient,
-  withTempDb,
+  withDb,
   filterForCommands,
   filterOutCommands,
   ignoreNsNotFound,

From c4eb0fa429440ac3d2b664be338b7747c8a7476c Mon Sep 17 00:00:00 2001
From: emadum <eric.adum@mongodb.com>
Date: Mon, 11 May 2020 10:36:55 -0400
Subject: [PATCH 07/10] dont save options, show warnings instead

---
 lib/mongo_client.js | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/lib/mongo_client.js b/lib/mongo_client.js
index 8be08637778..f5a6b072d8e 100644
--- a/lib/mongo_client.js
+++ b/lib/mongo_client.js
@@ -167,8 +167,6 @@ function MongoClient(url, options) {
     writeConcern: WriteConcern.fromOptions(options),
     namespace: new MongoDBNamespace('admin')
   };
-
-  this.originalOptions = Object.assign({}, this.s.options);
 }
 
 /**
@@ -259,9 +257,6 @@ MongoClient.prototype.close = function(force, callback) {
       this.topology = undefined;
       this.s.dbCache = new Map();
 
-      // restore options
-      this.s.options = Object.assign({}, this.originalOptions);
-
       cb(err);
     };
 

From 32c1ce807976916f34fa5f1c2e77c937c670e164 Mon Sep 17 00:00:00 2001
From: emadum <eric.adum@mongodb.com>
Date: Mon, 11 May 2020 12:19:46 -0400
Subject: [PATCH 08/10] fix for sessions

---
 lib/mongo_client.js              | 1 +
 test/functional/sessions.test.js | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/mongo_client.js b/lib/mongo_client.js
index f5a6b072d8e..13fc4622ac9 100644
--- a/lib/mongo_client.js
+++ b/lib/mongo_client.js
@@ -256,6 +256,7 @@ MongoClient.prototype.close = function(force, callback) {
       // clear out references to old topology
       this.topology = undefined;
       this.s.dbCache = new Map();
+      this.s.sessions = new Set();
 
       cb(err);
     };
diff --git a/test/functional/sessions.test.js b/test/functional/sessions.test.js
index c79510001d2..b4f88b68e6f 100644
--- a/test/functional/sessions.test.js
+++ b/test/functional/sessions.test.js
@@ -125,7 +125,7 @@ describe('Sessions', function() {
               // verify that the `endSessions` command was sent
               const lastCommand = test.commands.started[test.commands.started.length - 1];
               expect(lastCommand.commandName).to.equal('endSessions');
-              expect(client.topology.s.sessionPool.sessions).to.have.length(0);
+              expect(client.topology).to.not.exist;
             });
         });
       });
@@ -149,7 +149,7 @@ describe('Sessions', function() {
             // verify that the `endSessions` command was sent
             const lastCommand = test.commands.started[test.commands.started.length - 1];
             expect(lastCommand.commandName).to.equal('endSessions');
-            expect(client.topology.s.sessionPool.sessions).to.have.length(0);
+            expect(client.topology).to.not.exist;
           });
       });
     }

From dafab246372d4a5245befb5518c6b91000c07fd4 Mon Sep 17 00:00:00 2001
From: emadum <eric.adum@mongodb.com>
Date: Mon, 11 May 2020 12:50:38 -0400
Subject: [PATCH 09/10] save reference to topology

---
 lib/mongo_client.js | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/lib/mongo_client.js b/lib/mongo_client.js
index 13fc4622ac9..7b0c603a64f 100644
--- a/lib/mongo_client.js
+++ b/lib/mongo_client.js
@@ -241,11 +241,13 @@ MongoClient.prototype.close = function(force, callback) {
     force = false;
   }
 
+  const topology = this.topology;
+
   return maybePromise(this, callback, cb => {
     const completeClose = err => {
       this.emit('close', this);
 
-      if (!(this.topology instanceof NativeTopology)) {
+      if (!(topology instanceof NativeTopology)) {
         for (const item of this.s.dbCache) {
           item[1].emit('close', this);
         }
@@ -261,13 +263,13 @@ MongoClient.prototype.close = function(force, callback) {
       cb(err);
     };
 
-    if (this.topology == null) {
+    if (topology == null) {
       completeClose();
       return;
     }
 
-    this.topology.close(force, err => {
-      const autoEncrypter = this.topology.s.options.autoEncrypter;
+    topology.close(force, err => {
+      const autoEncrypter = topology.s.options.autoEncrypter;
       if (!autoEncrypter) {
         completeClose(err);
         return;

From 414e091d71161fbffb4ebf8692d151b9467512fb Mon Sep 17 00:00:00 2001
From: emadum <eric.adum@mongodb.com>
Date: Tue, 12 May 2020 15:02:17 -0400
Subject: [PATCH 10/10] fix flaky tryNext tests

---
 test/functional/change_stream.test.js | 96 +++++++++++++++------------
 test/functional/shared.js             | 72 +++++++++++++++++---
 2 files changed, 115 insertions(+), 53 deletions(-)

diff --git a/test/functional/change_stream.test.js b/test/functional/change_stream.test.js
index f8ad85a1273..5a834a92feb 100644
--- a/test/functional/change_stream.test.js
+++ b/test/functional/change_stream.test.js
@@ -6,6 +6,7 @@ var MongoNetworkError = require('../../lib/core').MongoNetworkError;
 var setupDatabase = require('./shared').setupDatabase;
 var withClient = require('./shared').withClient;
 var withDb = require('./shared').withDb;
+var withCollection = require('./shared').withCollection;
 var delay = require('./shared').delay;
 var co = require('co');
 var mock = require('mongodb-mock-server');
@@ -60,8 +61,12 @@ function tryNext(changeStream, callback) {
   let complete = false;
   function done(err, result) {
     if (complete) return;
-    // if the arity is 1 then this a callback for `more`
+    // if the arity is 1 then this is a callback for `more`
     if (arguments.length === 1) {
+      if (err instanceof Error) {
+        callback(err);
+        return;
+      }
       result = err;
       const batch = result.cursor.firstBatch || result.cursor.nextBatch;
       if (batch.length === 0) {
@@ -2633,64 +2638,67 @@ describe('Change Streams', function() {
   });
 
   describe('tryNext', function() {
-    it('should return null on single iteration of empty cursor', {
-      metadata: { requires: { topology: 'replicaset', mongodb: '>=3.6' } },
-      test: function() {
+    function withTemporaryCollectionOnDb(database, testFn) {
+      return function() {
         return withClient.bind(this)(
           withDb(
-            'testTryNext',
-            { w: 'majority' },
-            (db, done) => {
-              const changeStream = db.collection('test').watch();
-              tryNext(changeStream, (err, doc) => {
-                expect(err).to.not.exist;
-                expect(doc).to.not.exist;
-
-                changeStream.close(done);
-              });
-            },
-            true
+            database,
+            { helper: { drop: true } },
+            withCollection(
+              {
+                collection: { w: 'majority' },
+                helper: { create: true }
+              },
+              testFn
+            )
           )
         );
-      }
+      };
+    }
+    it('should return null on single iteration of empty cursor', {
+      metadata: { requires: { topology: 'replicaset', mongodb: '>=3.6' } },
+      test: withTemporaryCollectionOnDb('test_try_next_empty', (collection, done) => {
+        const changeStream = collection.watch();
+        tryNext(changeStream, (err, doc) => {
+          expect(err).to.not.exist;
+          expect(doc).to.not.exist;
+
+          changeStream.close(done);
+        });
+      })
     });
 
     it('should iterate a change stream until first empty batch', {
       metadata: { requires: { topology: 'replicaset', mongodb: '>=3.6' } },
-      test: function() {
-        return withClient.bind(this)(
-          withDb('testTryNext', { w: 'majority' }, (db, done) => {
-            const collection = db.collection('test');
-            const changeStream = collection.watch();
-            waitForStarted(changeStream, () => {
-              collection.insertOne({ a: 42 }, err => {
-                expect(err).to.not.exist;
+      test: withTemporaryCollectionOnDb('test_try_next_results', (collection, done) => {
+        const changeStream = collection.watch();
+        waitForStarted(changeStream, () => {
+          collection.insertOne({ a: 42 }, err => {
+            expect(err).to.not.exist;
 
-                collection.insertOne({ b: 24 }, err => {
-                  expect(err).to.not.exist;
-                });
-              });
+            collection.insertOne({ b: 24 }, err => {
+              expect(err).to.not.exist;
             });
+          });
+        });
 
-            tryNext(changeStream, (err, doc) => {
-              expect(err).to.not.exist;
-              expect(doc).to.exist;
+        tryNext(changeStream, (err, doc) => {
+          expect(err).to.not.exist;
+          expect(doc).to.exist;
 
-              tryNext(changeStream, (err, doc) => {
-                expect(err).to.not.exist;
-                expect(doc).to.exist;
+          tryNext(changeStream, (err, doc) => {
+            expect(err).to.not.exist;
+            expect(doc).to.exist;
 
-                tryNext(changeStream, (err, doc) => {
-                  expect(err).to.not.exist;
-                  expect(doc).to.not.exist;
+            tryNext(changeStream, (err, doc) => {
+              expect(err).to.not.exist;
+              expect(doc).to.not.exist;
 
-                  changeStream.close(done);
-                });
-              });
+              changeStream.close(done);
             });
-          })
-        );
-      }
+          });
+        });
+      })
     });
   });
 
diff --git a/test/functional/shared.js b/test/functional/shared.js
index 2d53e677c9e..5ee460f526d 100644
--- a/test/functional/shared.js
+++ b/test/functional/shared.js
@@ -57,24 +57,77 @@ function setupDatabase(configuration, dbsToClean) {
     );
 }
 
+/**
+ * use as the `testFn` of `withDb`
+ *
+ * @param {string} [name='test'] database name
+ * @param {object} [options] options
+ * @param {object} [options.collection={}] collection options
+ * @param {object} [options.helper={}] helper options
+ * @param {boolean} [options.helper.create] create collection before test
+ * @param {boolean} [options.helper.drop] drop collection after test
+ * @param {Function} testFn test function to execute
+ */
+function withCollection(name, options, testFn) {
+  if (arguments.length === 1) {
+    testFn = name;
+    name = 'test';
+    options = { collection: {}, helper: {} };
+  } else if (arguments.length === 2) {
+    testFn = options;
+    if (typeof name === 'string') {
+      options = { collection: {}, helper: {} };
+    } else {
+      options = name;
+      name = 'test';
+    }
+  }
+  function runTest(collection, done) {
+    testFn(collection, options.helper.drop ? () => collection.drop(done) : done);
+  }
+  if (options.helper.create) {
+    return (db, done) =>
+      db.createCollection(name, options, (err, collection) => {
+        if (err) return done(err);
+        runTest(collection, done);
+      });
+  }
+  return (db, done) => {
+    const collection = db.collection(name, options.collection);
+    runTest(collection, done);
+  };
+}
+
+
 /**
  * use as the `operation` of `withClient`
  *
- * @param {string} name database name
- * @param {object} [options] database options
+ * @param {string} [name='test'] database name
+ * @param {object} [options] options
+ * @param {object} [options.db={}] database options
+ * @param {object} [options.helper={}] helper options
+ * @param {boolean} [options.helper.drop] drop database after test
  * @param {Function} testFn test function to execute
- * @param {boolean} [drop] drop database after test
+ 
  */
-function withDb(name, options, testFn, drop) {
-  if (typeof options === 'function') {
-    drop = testFn;
+function withDb(name, options, testFn) {
+  if (arguments.length === 1) {
+    testFn = name;
+    name = 'test';
+    options = { db: {}, helper: {} };
+  } else if (arguments.length === 2) {
     testFn = options;
-    options = {};
+    if (typeof name === 'string') {
+      options = { db: {}, helper: {} };
+    } else {
+      options = name;
+      name = 'test';
+    }
   }
   return client =>
     new Promise(resolve => {
-      const db = client.db(name, options);
-      testFn(db, drop ? () => db.dropDatabase(resolve) : resolve);
+      const db = client.db(name, options.db);
+      testFn(db, options.helper.drop ? () => db.dropDatabase(resolve) : resolve);
     });
 }
 
@@ -277,6 +330,7 @@ module.exports = {
   withClient,
   withMonitoredClient,
   withDb,
+  withCollection,
   filterForCommands,
   filterOutCommands,
   ignoreNsNotFound,