https://github.com/lemonlion/mongodb.inmemoryemulator
An In-Process Emulator/Fake For MongoDB To Be Used For Integration/Component Testing
https://github.com/lemonlion/mongodb.inmemoryemulator
acceptance-testing component-testing database emulator fake integration-testing mock mocking-library mongodb testing testing-tools
Last synced: 17 days ago
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An In-Process Emulator/Fake For MongoDB To Be Used For Integration/Component Testing
- Host: GitHub
- URL: https://github.com/lemonlion/mongodb.inmemoryemulator
- Owner: lemonlion
- License: mit
- Created: 2026-04-25T17:19:13.000Z (18 days ago)
- Default Branch: main
- Last Pushed: 2026-04-26T10:36:11.000Z (17 days ago)
- Last Synced: 2026-04-26T11:23:07.558Z (17 days ago)
- Topics: acceptance-testing, component-testing, database, emulator, fake, integration-testing, mock, mocking-library, mongodb, testing, testing-tools
- Language: C#
- Homepage:
- Size: 226 KB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 12
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
- Agents: AGENTS.md
Awesome Lists containing this project
README
# 
MongoDB.InMemoryEmulator
[](https://www.nuget.org/packages/MongoDB.InMemoryEmulator/)
[](LICENSE)
A high-fidelity, in-process fake for the **MongoDB .NET/C# Driver** — zero Docker, zero network, instant startup.
## Why?
- **Instant** — ~0ms startup (vs 2-15s for Docker/Mongo2Go)
- **Portable** — No Docker, no `mongod` binaries, no ports
- **Reliable** — No flaky timeouts, port conflicts, or container failures
- **High-fidelity** — Real filter, update, and aggregation semantics (not mocks)
## Quick Start
```
dotnet add package MongoDB.InMemoryEmulator
```
### Unit Tests
```csharp
var result = InMemoryMongo.Create("orders");
var collection = result.Collection;
await collection.InsertOneAsync(new Order { Total = 99.99m });
var found = await collection.Find(o => o.Total > 50).FirstOrDefaultAsync();
```
### Integration Tests (DI)
```csharp
services.UseInMemoryMongoDB(options =>
{
options.DatabaseName = "testdb";
options.AddCollection("orders");
});
```
## What's Supported
| Feature | Status |
|---------|--------|
| Full CRUD (Insert, Find, Update, Replace, Delete, BulkWrite) | ✅ |
| Aggregation Pipeline (34 stages, 100+ expression operators) | ✅ |
| Indexes (Unique, Compound, Sparse, Partial Filter, TTL) | ✅ |
| Change Streams | ✅ |
| Transactions (snapshot isolation) | ✅ |
| GridFS | ✅ |
| Schema Validation (`$jsonSchema`) | ✅ |
| Capped Collections + Tailable Cursors | ✅ |
| Views | ✅ |
| LINQ (`AsQueryable()`) | ✅ |
| Fault Injection | ✅ |
| State Persistence (Export/Import) | ✅ |
| DI Integration (2 extension methods) | ✅ |
## NuGet Packages
| Framework | Package | Description | NuGet |
|---|---|---|---|
| **Core library** | `MongoDB.InMemoryEmulator` | Primary features | [](https://www.nuget.org/packages/MongoDB.InMemoryEmulator) |
| **JavaScript Triggers** | `MongoDB.InMemoryEmulator.JsTriggers` | `$function`, `$accumulator`, `$where` via Jint | [](https://www.nuget.org/packages/MongoDB.InMemoryEmulator.JsTriggers) |
## Documentation
See the [Wiki](https://github.com/lemonlion/MongoDB.InMemoryEmulator/wiki) for full documentation:
- [Getting Started](https://github.com/lemonlion/MongoDB.InMemoryEmulator/wiki/Getting-Started)
- [Setup Guide](https://github.com/lemonlion/MongoDB.InMemoryEmulator/wiki/Setup-Guide) (5 DI patterns)
- [Features](https://github.com/lemonlion/MongoDB.InMemoryEmulator/wiki/Features)
- [Filter & Update Operators](https://github.com/lemonlion/MongoDB.InMemoryEmulator/wiki/Filter-Update-Operators)
- [Aggregation Pipeline](https://github.com/lemonlion/MongoDB.InMemoryEmulator/wiki/Aggregation-Pipeline) (34 stages)
- [Migration Guide](https://github.com/lemonlion/MongoDB.InMemoryEmulator/wiki/Migration-Guide) (from Mongo2Go / Testcontainers)
- [Known Limitations](https://github.com/lemonlion/MongoDB.InMemoryEmulator/wiki/Known-Limitations)
## Requirements
- .NET 8.0+
- MongoDB.Driver 2.28.0+
## License
[MIT](LICENSE)