some progress

node_modules/mongoose/lib/helpers/topology/allServersUnknown.js

@@ -0,0 +1,12 @@
+'use strict';
+
+const getConstructorName = require('../getConstructorName');
+
+module.exports = function allServersUnknown(topologyDescription) {
+  if (getConstructorName(topologyDescription) !== 'TopologyDescription') {
+    return false;
+  }
+
+  const servers = Array.from(topologyDescription.servers.values());
+  return servers.length > 0 && servers.every(server => server.type === 'Unknown');
+};

node_modules/mongoose/lib/helpers/topology/isAtlas.js

@@ -0,0 +1,31 @@
+'use strict';
+
+const getConstructorName = require('../getConstructorName');
+
+/**
+ * @typedef { import('mongodb').TopologyDescription } TopologyDescription
+ */
+
+/**
+ * Checks if topologyDescription contains servers connected to an atlas instance
+ *
+ * @param  {TopologyDescription} topologyDescription
+ * @returns {boolean}
+ */
+module.exports = function isAtlas(topologyDescription) {
+  if (getConstructorName(topologyDescription) !== 'TopologyDescription') {
+    return false;
+  }
+
+  if (topologyDescription.servers.size === 0) {
+    return false;
+  }
+
+  for (const server of topologyDescription.servers.values()) {
+    if (server.host.endsWith('.mongodb.net') === false || server.port !== 27017) {
+      return false;
+    }
+  }
+
+  return true;
+};

node_modules/mongoose/lib/helpers/topology/isSSLError.js

@@ -0,0 +1,16 @@
+'use strict';
+
+const getConstructorName = require('../getConstructorName');
+
+const nonSSLMessage = 'Client network socket disconnected before secure TLS ' +
+  'connection was established';
+
+module.exports = function isSSLError(topologyDescription) {
+  if (getConstructorName(topologyDescription) !== 'TopologyDescription') {
+    return false;
+  }
+
+  const descriptions = Array.from(topologyDescription.servers.values());
+  return descriptions.length > 0 &&
+    descriptions.every(descr => descr.error && descr.error.message.indexOf(nonSSLMessage) !== -1);
+};