Testing File Storage¶

Deepstaging provides TestFileStore — a test double for IFileStore with call recording, seedable files, and a configurable presigned URL generator. No mocking libraries needed.

TestFileStore¶

Records every UploadAsync, DownloadAsync, DeleteAsync, ExistsAsync, GetMetadataAsync, and GetPresignedUrlAsync call. Seed files for download and existence checks.

var store = new TestFileStore();

// Seed a file
store.Seed("avatars/user-42.png", "image/png", imageBytes);

// ... run your handler that downloads files ...

// Assert the file was requested
await Assert.That(store.DownloadCalls).Contains("avatars/user-42.png");

Call Recording¶

Property	Type	Description
`UploadCalls`	`IReadOnlyList<UploadCall>`	All upload calls (key, content type, size)
`DownloadCalls`	`IReadOnlyList<string>`	All keys passed to `DownloadAsync`
`DeleteCalls`	`IReadOnlyList<string>`	All keys passed to `DeleteAsync`
`ExistsCalls`	`IReadOnlyList<string>`	All keys passed to `ExistsAsync`
`MetadataCalls`	`IReadOnlyList<string>`	All keys passed to `GetMetadataAsync`
`PresignedUrlCalls`	`IReadOnlyList<(string Key, TimeSpan Expiry)>`	All presigned URL requests

UploadCall Record¶

Each UploadAsync call is recorded as:

public record UploadCall(string Key, string ContentType, long Size);

Seeding Files¶

store.Seed("reports/q1.pdf", "application/pdf", pdfBytes);
store.Seed("images/logo.svg", "image/svg+xml", svgBytes);

Seeded files are returned by DownloadAsync, ExistsAsync, and GetMetadataAsync.

Configurable Presigned URLs¶

var store = new TestFileStore();

// Custom URL generator
store.OnGetPresignedUrl = (key, expiry) =>
    $"https://cdn.example.com/{key}?expires={expiry.TotalSeconds}";

var url = await store.GetPresignedUrlAsync("file.pdf", TimeSpan.FromHours(1));
// → "https://cdn.example.com/file.pdf?expires=3600"

Default generates memory:///{key}.

State Queries¶

// Check what's in the store
bool exists = store.Exists("avatars/user-42.png");
IReadOnlyCollection<string> allKeys = store.Keys();

Asserting Uploads¶

var store = new TestFileStore();

// ... run handler that uploads files ...

await Assert.That(store.UploadCalls).Count().IsEqualTo(1);
await Assert.That(store.UploadCalls[0].Key).IsEqualTo("avatars/user-42.png");
await Assert.That(store.UploadCalls[0].ContentType).IsEqualTo("image/png");

Reset Between Tests¶

store.Reset(); // Clears calls, seeded files, and restores default URL generator