Append Assertions

Every Append and AppendMany call returns an IAppendResult. The Cratis.Chronicle.Testing package provides built-in Should* extension methods for asserting on these results.

Assertion reference

Method	Asserts
`result.ShouldBeSuccessful()`	Operation succeeded with no violations or errors
`result.ShouldBeFailed()`	Operation failed (any violation or error)
`result.ShouldHaveConstraintViolations()`	At least one constraint violation is present
`result.ShouldNotHaveConstraintViolations()`	No constraint violations are present
`result.ShouldHaveConstraintViolationFor(name)`	A violation for the named constraint is present
`result.ShouldHaveConcurrencyViolations()`	At least one concurrency violation is present
`result.ShouldNotHaveConcurrencyViolations()`	No concurrency violations are present
`result.ShouldHaveErrors()`	At least one error is present
`result.ShouldNotHaveErrors()`	No errors are present

All Should* methods throw AppendResultAssertionException on failure. The exception message describes all violations and errors found, making it easy to diagnose failures.

Happy path assertion

var result = await scenario.EventLog.Append(authorId, new AuthorRegistered("Jane Smith"));
result.ShouldBeSuccessful();

Failure assertions

var result = await scenario.EventLog.Append(newAuthorId, new AuthorRegistered("Jane Smith"));
result.ShouldBeFailed();

Constraint violation assertions

Assert that a specific named constraint fired:

result.ShouldHaveConstraintViolations();
result.ShouldHaveConstraintViolationFor("UniqueAuthorName");

Assert that no constraint violations occurred:

result.ShouldNotHaveConstraintViolations();

Concurrency violation assertions

result.ShouldHaveConcurrencyViolations();
result.ShouldNotHaveConcurrencyViolations();

Error assertions

result.ShouldHaveErrors();
result.ShouldNotHaveErrors();

For asserting on the event sequence itself (tail sequence number, event types, and event content), see Event Sequence Assertions.

Example: testing a constraint violation end-to-end

Pre-seed state with Given, then verify the conflicting append is rejected with the expected constraint name:

var scenario = new EventScenario();

// Pre-seed: an author with this name is already registered
await scenario.Given
    .ForEventSource(existingAuthorId)
    .Events(new AuthorRegistered("John Doe"));

// Act: attempt to register the same name under a new event source
var result = await scenario.EventLog.Append(newAuthorId, new AuthorRegistered("John Doe"));

result.ShouldBeFailed();
result.ShouldHaveConstraintViolations();
result.ShouldHaveConstraintViolationFor("UniqueAuthorName");