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Snapshot assertions with Verify

Sometimes the clearest assertion is “the whole thing looks like this” — every field of a persisted entity, not a dozen hand-written Assert.Thats. Verify snapshots the object to a committed .verified.txt file and fails when it drifts. Mokkit wraps it in a normal inspect verb, so a snapshot is just another word in your vocabulary.

A Verify inspect verb

Section titled “A Verify inspect verb”

Centralise the Verify settings once, then expose a verb that snapshots any value (with [CallerFilePath] so the snapshot lands next to the test):

public static class VerifierSetup
{
    public static VerifySettings Default(Action<VerifySettings>? configure = null)
    {
        var settings = new VerifySettings();
        settings.DontScrubGuids();               // our ids are deterministic — show them literally
        settings.DontIgnoreEmptyCollections();
        configure?.Invoke(settings);
        return settings;
    }
}


public static ITestInspect Verify<T>(
    this ITestInspect inspect, Capture<T> capture,
    Action<VerifySettings>? configure = null,
    [CallerFilePath] string sourceFile = "") =>
    inspect.Then(async _ => await Verifier.Verify(capture.Value, VerifierSetup.Default(configure), sourceFile));

Using it in a chain

Section titled “Using it in a chain”

Read the row into a capture, then hand that capture to Verify — the snapshot covers every field at once:

await Inspect
    .SaveResult(result).IsSuccess(ArrangeClient.FixedClientId)
    .DbClientById(clientId, out var saved, c => Assert.That(c, Is.Not.Null))
    .Verify(saved)                          // snapshot the whole persisted entity
    .CacheUpdated(clientId)
    .EventPublished(clientId, "created");

Because the clock and ids are deterministic, the snapshot is stable run to run — CreatedAt is always the fixed time, the id is always the fixed Guid — so a diff means a real change, not noise.

The workflow

Section titled “The workflow”
  1. First run writes <TestClass>.<TestName>.received.txt and the test “fails”.
  2. Review it. If it’s right, accept it — rename to .verified.txt (or use a clipboard/accept tool) and commit it.
  3. From then on, any drift from the committed snapshot fails the test with a diff.

Next

Section titled “Next”