Table of Contents

Tips & Tricks

A grab‑bag of pragmatic techniques to keep scenarios fast, readable, and low‑ceremony.

1. Prefer Delegates / Function Pointers Over Inline Lambdas (Where Hot)

For extremely hot paths (thousands of scenarios), the JIT can better optimize static delegates or function pointers.

static int Inc(int x) => x + 1;
await Given(() => 1)
    .When("+1", Inc) // delegate reuse
    .Then("> 0", v => v > 0);

In most test suites the difference is negligible—use only if profiling justifies it.

2. Title Economy

Keep step titles business readable; avoid leaking implementation detail unless it clarifies intent. Bad: When invoke Handler.Process(OrderDto{...}) Better: When submitting a valid order

3. Reuse Seed Builders

Extract object graph creation into factories:

static Order NewOrder(params string[] skus) => new(skus.Select(s => new LineItem(s)).ToList());
await Given("new order", () => NewOrder("A123")) ...

4. Fast Data Variations

Leverage parameterized tests (xUnit [Theory], NUnit [TestCase]) wrapping TinyBDD chains for data sets.

[Theory]
[InlineData(0)]
[InlineData(5)]
public async Task Adds(int start) =>
    await Given(() => start)
        .When("+1", x => x + 1)
        .Then("> start", v => v > start)
        .AssertPassed();

5. Combine Predicates with Fluent Expectations

Use simple predicates for binary checks, fluent expectations for multi‑facet diagnostics.

.Then("status ok", r => r.Status == 200)
.And("payload ok", r => Expect.For(r.Body).ToNotBeNull().ToSatisfy(b => b.Length > 0, "have content"))

6. Snapshot / Golden File Verification

If you want to snapshot outputs, capture CurrentItem after the chain and compare serialized form (serialize with stable ordering). Keep snapshots versioned.

7. Parallelization Caution

Ambient context uses AsyncLocal—safe for parallel test runners. Avoid mutating shared static state in step delegates.

8. Timeouts Strategically

Use ScenarioOptions.StepTimeout for untrusted integrations; keep local pure logic un‑timed to avoid noise.

var ctx = Bdd.CreateContext(this, options: new ScenarioOptions { StepTimeout = TimeSpan.FromSeconds(2) });

9. Partial Scenario Reconfiguration

Duplicate setups with slight meta differences via Bdd.ReconfigureContext.

var fastCtx = Bdd.ReconfigureContext(ctx, proto => proto.ScenarioName = proto.ScenarioName + " (fast) ");

10. Rich Failure Context

Attach hints (With) sparingly to point to actionable remediation steps (config file, external dependency name, etc.). Avoid restating the assertion itself.

11. Logging During Execution

Use Pipeline.BeforeStep / AfterStep hooks (via adapter that exposes pipeline) to stream to logs. Or inspect ScenarioContext.IO after run.

12. Keep Scenarios Deterministic

Eliminate non‑determinism: random seeds, time providers, network calls replaced with fakes. Deterministic tests reduce flaky noise and improve perceived reliability.

Proceed to: Extensibility & Advanced

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