MongoDB’s document model introduces testing challenges that relational database tests do not have: schema flexibility (different documents can have different fields), aggregation pipelines, geospatial queries, and text search. Testing these against an embedded Flapdoodle MongoDB works for basic CRUD but breaks down for aggregation pipelines, custom index types, and MongoDB-version-specific behavior. This article covers MongoDB testing with a real MongoDB container. What You’ll Learn MongoDBContainer setup and @ServiceConnection @DataMongoTest slice testing for repositories Testing aggregation pipelines Testing compound indexes and text indexes Querying documents with MongoTemplate Testing document validation rules Dependencies <dependency> <groupId>org.