testcontainers-shared-fixture

What problem does it solve?

Many xUnit integration test classes each start their own MongoDbContainer which multiplies startup time and inflates CI run durations; this pattern reduces repeated container startups by sharing a single Testcontainers MongoDB instance per xUnit collection while preserving test isolation.

Core Features & Use Cases

• Shared Fixture Lifecycle: Use a MongoDbFixture implementing IAsyncLifetime to start and stop one MongoDbContainer per xUnit collection.
• Collection-level Parallelism: Define ICollectionFixture-based collections so related test classes share a container while different collections run in parallel.
• Per-test Isolation: Create unique databases per test method using GUID-based names to maintain isolation without per-class containers.
• CI Performance: Configure xunit.runner.json to enable collection-level parallelization and dramatically reduce total test startup time.
• Practical Use Case: Ideal for .NET integration tests that use Testcontainers and MongoDB where dozens of test classes previously created slow sequential containers.

Quick Start

Convert per-class MongoDbContainer setups into a single MongoDbFixture shared via ICollectionFixture and enable parallelizeTestCollections in xunit.runner.json to cut container startup overhead.