fix: skip config validation when using connector

This changeset fixes a problem in the original custom `connector`
factory method implementation that required the `server` config property
to be defined even though its value is ignored.

Removing the validation when `config.options.connector` is defined fixes
the problem.

Ref: #1540
Fixes: #1541
Signed-off-by: Ruy Adorno <ruyadorno@google.com>

Author: ruyadorno

src/connection.ts

@@ -1052,7 +1052,7 @@ class Connection extends EventEmitter {
       throw new TypeError('The "config" argument is required and must be of type Object.');
     }
 
-    if (typeof config.server !== 'string') {
+    if (typeof config.server !== 'string' && !config.options!.connector) {
       throw new TypeError('The "config.server" property is required and must be of type string.');
     }
 
@@ -1343,8 +1343,15 @@ class Connection extends EventEmitter {
         if (typeof config.options.connector !== 'function') {
           throw new TypeError('The "config.options.connector" property must be a function.');
         }
+        if (config.server) {
+          throw new Error('Server and connector are mutually exclusive, but ' + config.server + ' and a connector function were provided');
+        }
+        if (config.options.port) {
+          throw new Error('Port and connector are mutually exclusive, but ' + config.options.port + ' and a connector function were provided');
+        }
 
         this.config.options.connector = config.options.connector;
+        this.config.options.port = undefined;
       }
 
       if (config.options.cryptoCredentialsDetails !== undefined) {
@@ -1900,7 +1907,10 @@ class Connection extends EventEmitter {
   initialiseConnection() {
     const signal = this.createConnectTimer();
 
-    if (this.config.options.port) {
+    if (this.config.options.connector) {
+      // port and multiSubnetFailover are not used when using a custom connector
+      return this.connectOnPort(0, false, signal, this.config.options.connector);
+    } else if (this.config.options.port) {
       return this.connectOnPort(this.config.options.port, this.config.options.multiSubnetFailover, signal, this.config.options.connector);
     } else {
       return instanceLookup({
@@ -1995,7 +2005,12 @@ class Connection extends EventEmitter {
         this.socket = socket;
 
         this.closed = false;
-        this.debug.log('connected to ' + this.config.server + ':' + this.config.options.port);
+
+        const message =
+          'connected to ' + this.config.server + ':' + this.config.options.port;
+        const customConnectorMessage =
+          'connected via custom connector';
+        this.debug.log(customConnector ? customConnectorMessage : message);
 
         this.sendPreLogin();
         this.transitionTo(this.STATE.SENT_PRELOGIN);
@@ -2073,8 +2088,10 @@ class Connection extends EventEmitter {
    */
   connectTimeout() {
     const message = `Failed to connect to ${this.config.server}${this.config.options.port ? `:${this.config.options.port}` : `\\${this.config.options.instanceName}`} in ${this.config.options.connectTimeout}ms`;
-    this.debug.log(message);
-    this.emit('connect', new ConnectionError(message, 'ETIMEOUT'));
+    const customConnectorMessage = `Failed to connect using custom connector in ${this.config.options.connectTimeout}ms`;
+    const errMessage = this.config.options.connector ? customConnectorMessage : message;
+    this.debug.log(errMessage);
+    this.emit('connect', new ConnectionError(errMessage, 'ETIMEOUT'));
     this.connectTimer = undefined;
     this.dispatchEvent('connectTimeout');
   }
@@ -2202,8 +2219,10 @@ class Connection extends EventEmitter {
   socketError(error: Error) {
     if (this.state === this.STATE.CONNECTING || this.state === this.STATE.SENT_TLSSSLNEGOTIATION) {
       const message = `Failed to connect to ${this.config.server}:${this.config.options.port} - ${error.message}`;
-      this.debug.log(message);
-      this.emit('connect', new ConnectionError(message, 'ESOCKET'));
+      const customConnectorMessage = `Failed to connect using custom connector - ${error.message}`;
+      const errMessage = this.config.options.connector ? customConnectorMessage : message;
+      this.debug.log(errMessage);
+      this.emit('connect', new ConnectionError(errMessage, 'ESOCKET'));
     } else {
       const message = `Connection lost - ${error.message}`;
       this.debug.log(message);
@@ -2228,15 +2247,21 @@ class Connection extends EventEmitter {
    * @private
    */
   socketClose() {
-    this.debug.log('connection to ' + this.config.server + ':' + this.config.options.port + ' closed');
+    const message = 'connection to ' + this.config.server + ':' + this.config.options.port + ' closed';
+    const customConnectorMessage = 'connection closed';
+    this.debug.log(this.config.options.connector ? customConnectorMessage : message);
     if (this.state === this.STATE.REROUTING) {
-      this.debug.log('Rerouting to ' + this.routingData!.server + ':' + this.routingData!.port);
+      const message = 'Rerouting to ' + this.routingData!.server + ':' + this.routingData!.port;
+      const customConnectorMessage = 'Rerouting';
+      this.debug.log(this.config.options.connector ? customConnectorMessage : message);
 
       this.dispatchEvent('reconnect');
     } else if (this.state === this.STATE.TRANSIENT_FAILURE_RETRY) {
       const server = this.routingData ? this.routingData.server : this.config.server;
       const port = this.routingData ? this.routingData.port : this.config.options.port;
-      this.debug.log('Retry after transient failure connecting to ' + server + ':' + port);
+      const message = 'Retry after transient failure connecting to ' + server + ':' + port;
+      const customConnectorMessage = 'Retry after transient failure connecting';
+      this.debug.log(this.config.options.connector ? customConnectorMessage : message);
 
       this.dispatchEvent('retry');
     } else {

test/unit/custom-connector.js

@@ -28,7 +28,6 @@ describe('custom connector', function() {
     const host = server.address().address;
     const port = server.address().port;
     const connection = new Connection({
-      server: host,
       options: {
         connector: async () => {
           customConnectorCalled = true;
@@ -37,7 +36,6 @@ describe('custom connector', function() {
             port,
           });
         },
-        port
       },
     });
 
@@ -59,4 +57,63 @@ describe('custom connector', function() {
 
     connection.connect();
   });
+
+  it('should emit socket error custom connector msg', function(done) {
+    const connection = new Connection({
+      options: {
+        connector: async () => {
+          throw new Error('ERR');
+        },
+      },
+    });
+
+    connection.connect((err) => {
+      assert.strictEqual(
+        err.code,
+        'ESOCKET',
+        'should emit expected error code'
+      );
+      assert.strictEqual(
+        err.message,
+        'Failed to connect using custom connector - ERR',
+        'should emit expected custom connector error msg'
+      );
+      done();
+    });
+  });
+
+  it('should only accept functions', function(done) {
+    assert.throws(() => {
+      new Connection({
+        options: {
+          connector: 'foo',
+        },
+      });
+    }, Error, 'The "config.options.connector" property must be a function.');
+    done();
+  });
+
+  it('should not allow setting both server and connector options', function(done) {
+    assert.throws(() => {
+      new Connection({
+        server: '0.0.0.0',
+        options: {
+          connector: async () => {},
+        },
+      });
+    }, Error, 'Server and connector are mutually exclusive, but 0.0.0.0 and a connector function were provided');
+    done();
+  });
+
+  it('should not allow setting both port and connector options', function(done) {
+    assert.throws(() => {
+      new Connection({
+        options: {
+          connector: async () => {},
+          port: 8080,
+        },
+      });
+    }, Error, 'Port and connector are mutually exclusive, but 8080 and a connector function were provided');
+    done();
+  });
 });