diff --git a/src/operations/map_reduce.ts b/src/operations/map_reduce.ts
index d89bb5202f4..5786b9a6a4c 100644
--- a/src/operations/map_reduce.ts
+++ b/src/operations/map_reduce.ts
@@ -8,7 +8,7 @@ import {
   Callback,
   maxWireVersion
 } from '../utils';
-import { ReadPreference, ReadPreferenceMode } from '../read_preference';
+import { ReadPreference } from '../read_preference';
 import { CommandOperation, CommandOperationOptions } from './command';
 import type { Server } from '../sdam/server';
 import type { Collection } from '../collection';
diff --git a/test/unit/core/connection_string.test.js b/test/unit/core/connection_string.test.js
index 40d9ff0d9c5..b61e649234d 100644
--- a/test/unit/core/connection_string.test.js
+++ b/test/unit/core/connection_string.test.js
@@ -220,72 +220,72 @@ describe('Connection String', function () {
     suites.forEach(suite => {
       describe(suite.name, function () {
         suite.tests.forEach(test => {
-          // it(test.description, {
-          //   metadata: { requires: { topology: 'single' } },
-          //   test: function (done) {
-          //     if (skipTests.indexOf(test.description) !== -1) {
-          //       return this.skip();
-          //     }
-
-          //     const valid = test.valid;
-          //     parseConnectionString(test.uri, { caseTranslate: false }, function (err, result) {
-          //       if (valid === false) {
-          //         expect(err).to.exist;
-          //         expect(err).to.be.instanceOf(MongoParseError);
-          //         expect(result).to.not.exist;
-          //       } else {
-          //         expect(err).to.not.exist;
-          //         expect(result).to.exist;
-
-          //         // remove data we don't track
-          //         if (test.auth && test.auth.password === '') {
-          //           test.auth.password = null;
-          //         }
-
-          //         if (test.hosts != null) {
-          //           test.hosts = test.hosts.map(host => {
-          //             delete host.type;
-          //             host.host = punycode.toASCII(host.host);
-          //             return host;
-          //           });
-
-          //           // remove values that require no validation
-          //           test.hosts.forEach(host => {
-          //             Object.keys(host).forEach(key => {
-          //               if (host[key] == null) delete host[key];
-          //             });
-          //           });
-
-          //           expect(result.hosts).to.containSubset(test.hosts);
-          //         }
-
-          //         if (test.auth) {
-          //           if (test.auth.db != null) {
-          //             expect(result.auth).to.have.property('db');
-          //             expect(result.auth.db).to.eql(test.auth.db);
-          //           }
-
-          //           if (test.auth.username != null) {
-          //             expect(result.auth).to.have.property('username');
-          //             expect(result.auth.username).to.eql(test.auth.username);
-          //           }
-
-          //           if (test.auth.password != null) {
-          //             expect(result.auth).to.have.property('password');
-          //             expect(result.auth.password).to.eql(test.auth.password);
-          //           }
-          //         }
-
-          //         if (test.options != null) {
-          //           // it's possible we have options which are not explicitly included in the spec test
-          //           expect(result.options).to.deep.include(test.options);
-          //         }
-          //       }
-
-          //       done();
-          //     });
-          //   }
-          // });
+          it(test.description, {
+            metadata: { requires: { topology: 'single' } },
+            test: function (done) {
+              if (skipTests.indexOf(test.description) !== -1) {
+                return this.skip();
+              }
+
+              const valid = test.valid;
+              parseConnectionString(test.uri, { caseTranslate: false }, function (err, result) {
+                if (valid === false) {
+                  expect(err).to.exist;
+                  expect(err).to.be.instanceOf(MongoParseError);
+                  expect(result).to.not.exist;
+                } else {
+                  expect(err).to.not.exist;
+                  expect(result).to.exist;
+
+                  // remove data we don't track
+                  if (test.auth && test.auth.password === '') {
+                    test.auth.password = null;
+                  }
+
+                  if (test.hosts != null) {
+                    test.hosts = test.hosts.map(host => {
+                      delete host.type;
+                      host.host = punycode.toASCII(host.host);
+                      return host;
+                    });
+
+                    // remove values that require no validation
+                    test.hosts.forEach(host => {
+                      Object.keys(host).forEach(key => {
+                        if (host[key] == null) delete host[key];
+                      });
+                    });
+
+                    expect(result.hosts).to.containSubset(test.hosts);
+                  }
+
+                  if (test.auth) {
+                    if (test.auth.db != null) {
+                      expect(result.auth).to.have.property('db');
+                      expect(result.auth.db).to.eql(test.auth.db);
+                    }
+
+                    if (test.auth.username != null) {
+                      expect(result.auth).to.have.property('username');
+                      expect(result.auth.username).to.eql(test.auth.username);
+                    }
+
+                    if (test.auth.password != null) {
+                      expect(result.auth).to.have.property('password');
+                      expect(result.auth.password).to.eql(test.auth.password);
+                    }
+                  }
+
+                  if (test.options != null) {
+                    // it's possible we have options which are not explicitly included in the spec test
+                    expect(result.options).to.deep.include(test.options);
+                  }
+                }
+
+                done();
+              });
+            }
+          });
 
           it(`${test.description} -- new MongoOptions parser`, function () {
             if (skipTests.includes(test.description)) {