update tests and impl

Author: W-A-James

src/error.ts

@@ -1,10 +1,10 @@
-import type { Document } from './bson';
+import type { Document, ObjectId } from './bson';
 import {
   type ClientBulkWriteError,
   type ClientBulkWriteResult
 } from './operations/client_bulk_write/common';
 import type { ServerType } from './sdam/common';
-import type { TopologyVersion } from './sdam/server_description';
+import type { ServerDescription, TopologyVersion } from './sdam/server_description';
 import type { TopologyDescription } from './sdam/topology_description';
 
 /** @public */
@@ -340,6 +340,43 @@ export class MongoRuntimeError extends MongoDriverError {
   }
 }
 
+/**
+ * An error generated when a primary server is marked stale, never directly thrown
+ * @privateRemarks
+ * Should **never** be directly instantiated.
+ *
+ * @public
+ * @category Error
+ */
+export class MongoStalePrimaryError extends MongoRuntimeError {
+  /**
+   * **Do not use this constructor!**
+   *
+   * Meant for internal use only.
+   *
+   * @remarks
+   * This class is only meant to be constructed within the driver. This constructor is
+   * not subject to semantic versioning compatibility guarantees and may change at any time.
+   *
+   * @public
+   **/
+  constructor(
+    serverDescription: ServerDescription,
+    maxSetVersion: number | null,
+    maxElectionId: ObjectId | null,
+    options?: { cause?: Error }
+  ) {
+    super(
+      `primary marked stale due to electionId/setVersion mismatch: server setVersion: ${serverDescription.setVersion}, server electionId: ${serverDescription.electionId}, topology setVersion: ${maxSetVersion}, topology electionId: ${maxElectionId}`,
+      options
+    );
+  }
+
+  override get name(): string {
+    return 'MongoStalePrimaryError';
+  }
+}
+
 /**
  * An error generated when a batch command is re-executed after one of the commands in the batch
  * has failed

src/sdam/topology_description.ts

@@ -1,6 +1,6 @@
 import { EJSON, type ObjectId } from '../bson';
 import * as WIRE_CONSTANTS from '../cmap/wire_protocol/constants';
-import { MongoError, MongoRuntimeError } from '../error';
+import { type MongoError, MongoRuntimeError, MongoStalePrimaryError } from '../error';
 import { compareObjectId, shuffle } from '../utils';
 import { ServerType, TopologyType } from './common';
 import { ServerDescription } from './server_description';
@@ -401,9 +401,7 @@ function updateRsFromPrimary(
       serverDescriptions.set(
         serverDescription.address,
         new ServerDescription(serverDescription.address, undefined, {
-          error: new MongoError(
-            `primary marked stale due to electionId/setVersion mismatch: server setVersion: ${serverDescription.setVersion}, server electionId: ${serverDescription.electionId}, topology setVersion: ${maxSetVersion}, topology electionId: ${maxElectionId}`
-          )
+          error: new MongoStalePrimaryError(serverDescription, maxSetVersion, maxElectionId)
         })
       );
 
@@ -421,9 +419,7 @@ function updateRsFromPrimary(
           serverDescriptions.set(
             serverDescription.address,
             new ServerDescription(serverDescription.address, undefined, {
-              error: new MongoError(
-                `primary marked stale due to electionId/setVersion mismatch: server setVersion: ${serverDescription.setVersion}, server electionId: ${serverDescription.electionId}, topology setVersion: ${maxSetVersion}, topology electionId: ${maxElectionId}`
-              )
+              error: new MongoStalePrimaryError(serverDescription, maxSetVersion, maxElectionId)
             })
           );
 
@@ -449,9 +445,7 @@ function updateRsFromPrimary(
       serverDescriptions.set(
         address,
         new ServerDescription(server.address, undefined, {
-          error: new MongoError(
-            `primary marked stale due to electionId/setVersion mismatch: server setVersion: ${server.setVersion}, server electionId: ${server.electionId}, topology setVersion: ${maxSetVersion}, topology electionId: ${maxElectionId}`
-          )
+          error: new MongoStalePrimaryError(serverDescription, maxSetVersion, maxElectionId)
         })
       );
 

test/unit/assorted/server_discovery_and_monitoring.spec.test.ts

@@ -271,7 +271,7 @@ function normalizeServerDescription(serverDescription) {
     // it as `Unknown`.
     serverDescription.type = 'Unknown';
   }
-  serverDescription.error == serverDescription?.error?.message;
+  //serverDescription.error = serverDescription?.error?.message;
 
   return serverDescription;
 }
@@ -475,7 +475,7 @@ function assertTopologyDescriptionOutcomeExpectations(
       } else if (expectedKey !== 'error') {
         expect(actualServer).to.have.deep.property(expectedKey, expectedValue);
       } else {
-        // Check that if we have
+        // pull the message off the error if it is present
         expect(actualServer).to.have.deep.property(expectedKey).instanceof(MongoError);
         expect(actualServer).property(expectedKey).property('message').includes(expectedValue);
       }