Rig.TUnit.Observability.Logging 0.1.0-beta.2

Rig.TUnit.Observability.Logging

In-memory ILogger<T> capture with structured-scope stack, fluent LogAssert, and runtime AntiPatternDetector (PII + interpolated templates).

What this package is

A logging integration-test fixture. LoggingFixture provides a CreateLogger(category) factory backed by an in-memory ILoggerProvider that captures every log entry plus the full BeginScope stack. LogAssert gives fluent assertions over the captured entries: LogAssert.Logged(fx, LogLevel.Information).WithProperty("OrderId", 42).Once(). AntiPatternDetector runs at assertion time and catches two of the most common logging foot-guns: PII in structured properties and string-interpolated log templates.

When to use it

• Asserting log messages emitted under specific conditions.
• Regression-testing log shape after a refactor.
• Catching interpolated templates ($"...") before they land in prod.
• Not for: volumetric load testing — the in-memory capture is unbounded and will OOM on millions of entries.

Prerequisites

• .NET 10 SDK
• Microsoft.Extensions.Logging (transitive)

Quick start

using Microsoft.Extensions.Logging;
using Rig.TUnit.Observability.Logging.Fixtures;

await using var fx = new LoggingFixture();
await fx.InitializeAsync();

fx.CreateLogger("Orders").LogInformation("Processing {OrderId}", 42);

Options

Fixture + helper APIs

• Rig.TUnit.Observability.Logging.Fixtures.LoggingFixture
• Rig.TUnit.Observability.Logging.Options.LoggingFixtureOptions
• Rig.TUnit.Observability.Logging.Builder.LoggingRigBuilder
• Rig.TUnit.Observability.Logging.Assertions.LogAssert
• Rig.TUnit.Observability.Logging.Helpers.AntiPatternDetector

Per-test isolation

Each LoggingFixture owns its entry buffer. No shared state. Safe under full parallelism.

Parallelism + performance

• Fixture construction: ~1 ms.
• Per-log overhead: ~5 µs (capture + scope clone).
• Safe under full parallelism.

Troubleshooting

• LogAssert.Logged(…).Once() fails with 0 — the MinLevel filtered the entry out. Check fx.MinLevel matches the level you expect.
• AntiPatternDetector flags a non-PII property — tune the AntiPatternDetector.IgnoreProperties list for the false positive.

See .

Provider quirks + edge cases

• BeginScope state is captured as an opaque object — the harness deep-clones it via JsonSerializer so later mutations do not corrupt the captured scope.
• Structured properties under {Name} placeholders are what gets captured; positional {0}-style logs capture only the formatted string. AntiPatternDetector flags the positional form.

Benchmarks

See ; baseline in benchmarks/baseline-005.json.

Related docs

• Family base:
• Sibling:

License

MIT. See .