fix(NODE-3767): don't delete dbName if authSource is provided

src/connection_string.ts

@@ -291,11 +291,6 @@ export function parseOptions(
     }
   }
 
-  if (urlOptions.has('authSource')) {
-    // If authSource is an explicit key in the urlOptions we need to remove the dbName
-    urlOptions.delete('dbName');
-  }
-
   const objectOptions = new CaseInsensitiveMap(
     Object.entries(options).filter(([, v]) => v != null)
   );

test/unit/connection_string.test.js

@@ -99,6 +99,17 @@ describe('Connection String', function () {
     expect(options.credentials.source).to.equal('0001');
   });
 
+  it('should not remove dbName from the options if authSource is provided', function () {
+    const dbName = 'my-db-name';
+    const authSource = 'admin';
+    const options = parseOptions(
+      `mongodb://myName:myPassword@localhost:27017/${dbName}?authSource=${authSource}`
+    );
+
+    expect(options).has.property('dbName', dbName);
+    expect(options.credentials).to.have.property('source', authSource);
+  });
+
   it('should parse a replicaSet with a leading number', function () {
     const options = parseOptions('mongodb://localhost/?replicaSet=123abc');
     expect(options).to.have.property('replicaSet');

test/unit/mongo_client.test.js

@@ -787,4 +787,63 @@ describe('MongoOptions', function () {
     // Nothing wrong with the name, just DNE
     expect(thrownError).to.have.property('code', 'ENOTFOUND');
   });
+
+  describe('dbName and authSource', () => {
+    describe('in the URI', () => {
+      it('should set the database name to the dbName in the uri', () => {
+        const client = new MongoClient('mongodb://u:p@host/myDb');
+        const db = client.db();
+        expect(db).to.have.property('databaseName', 'myDb');
+        expect(client).to.have.nested.property('options.credentials.source', 'myDb');
+      });
+      it('should set the database name to the uri pathname and respect the authSource option', () => {
+        const client = new MongoClient('mongodb://u:p@host/myDb?authSource=myAuthDb');
+        const db = client.db();
+        expect(db).to.have.property('databaseName', 'myDb');
+        expect(client).to.have.nested.property('options.credentials.source', 'myAuthDb');
+      });
+      it('should set the database name to the uri pathname and respect the authSource option in options object', () => {
+        const client = new MongoClient('mongodb://u:p@host/myDb', { authSource: 'myAuthDb' });
+        const db = client.db();
+        expect(db).to.have.property('databaseName', 'myDb');
+        expect(client).to.have.nested.property('options.credentials.source', 'myAuthDb');
+      });
+    });
+
+    describe('in the options object', () => {
+      it('should set the database name to the dbName in the options object', () => {
+        const client = new MongoClient('mongodb://u:p@host', { dbName: 'myDb' });
+        const db = client.db();
+        expect(db).to.have.property('databaseName', 'myDb');
+        expect(client).to.have.nested.property('options.credentials.source', 'myDb');
+      });
+      it('should set the database name to dbName and respect the authSource option', () => {
+        const client = new MongoClient('mongodb://u:p@host?authSource=myAuthDb', {
+          dbName: 'myDb'
+        });
+        const db = client.db();
+        expect(db).to.have.property('databaseName', 'myDb');
+        expect(client).to.have.nested.property('options.credentials.source', 'myAuthDb');
+      });
+      it('should set the database name to dbName and respect the authSource option in options object', () => {
+        const client = new MongoClient('mongodb://u:p@host', {
+          dbName: 'myDb',
+          authSource: 'myAuthDb'
+        });
+        const db = client.db();
+        expect(db).to.have.property('databaseName', 'myDb');
+        expect(client).to.have.nested.property('options.credentials.source', 'myAuthDb');
+      });
+
+      it('should set the database name to dbName in options object and respect the authSource option in options object', () => {
+        const client = new MongoClient('mongodb://u:p@host/myIgnoredDb', {
+          dbName: 'myDb',
+          authSource: 'myAuthDb'
+        });
+        const db = client.db();
+        expect(db).to.have.property('databaseName', 'myDb');
+        expect(client).to.have.nested.property('options.credentials.source', 'myAuthDb');
+      });
+    });
+  });
 });