fix(shell-api): Add support for running aggregate database with a single stage MONGOSH-1868

packages/shell-api/src/collection.ts

@@ -164,7 +164,7 @@ export default class Collection extends ShellApiWithMongoClass {
   async aggregate(
     pipeline: Document[],
     options: Document & { explain: ExplainVerbosityLike }
-  ): Promise<Document>;
+  ): Promise<AggregationCursor>;
   async aggregate(...stages: Document[]): Promise<AggregationCursor>;
   @returnsPromise
   @returnType('AggregationCursor')
@@ -191,7 +191,10 @@ export default class Collection extends ShellApiWithMongoClass {
       this._database._name,
       this._name,
       pipeline,
-      { ...(await this._database._baseOptions()), ...aggOptions },
+      {
+        ...(await this._database._baseOptions()),
+        ...aggOptions,
+      },
       dbOptions
     );
     const cursor = new AggregationCursor(this._mongo, providerCursor);

packages/shell-api/src/database.spec.ts

@@ -390,6 +390,17 @@ describe('Database', function () {
         serviceProviderCursor = stubInterface<ServiceProviderAggCursor>();
       });
 
+      it('throws if the given argument is not an array', async function () {
+        let caughtError: MongoshInvalidInputError | undefined;
+        // eslint-disable-next-line @typescript-eslint/no-unsafe-argument
+        await database.aggregate({} as any).catch((err) => {
+          caughtError = err;
+        });
+        expect(caughtError?.message).contains(
+          'Aggregate pipeline argument must be an array'
+        );
+      });
+
       it('calls serviceProvider.aggregateDb with pipleline and options', async function () {
         await database.aggregate([{ $piplelineStage: {} }], { options: true });
 

packages/shell-api/src/database.ts

@@ -432,6 +432,14 @@ export default class Database extends ShellApiWithMongoClass {
       );
     }
     assertArgsDefinedType([pipeline], [true], 'Database.aggregate');
+
+    if (!Array.isArray(pipeline)) {
+      throw new MongoshInvalidInputError(
+        'Aggregate pipeline argument must be an array',
+        CommonErrors.InvalidArgument
+      );
+    }
+
     this._emitDatabaseApiCall('aggregate', { options, pipeline });
 
     const { aggOptions, dbOptions, explain } = adaptAggregateOptions(options);
@@ -1429,6 +1437,7 @@ export default class Database extends ShellApiWithMongoClass {
         CommonErrors.CommandFailed
       );
     }
+    // eslint-disable-next-line @typescript-eslint/no-unnecessary-type-assertion
     for (const cmdDescription of Object.values(result.commands) as Document[]) {
       if ('slaveOk' in cmdDescription) {
         cmdDescription.secondaryOk = cmdDescription.slaveOk;