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Eventual assertions for FluentAssertions
FluentAssertions.Eventual
is an extension that allows to wait for FluentAssertions
checks to pass which can be useful when writing end-to-end tests.
Basic usage
Any FluentAssertions
checks can be placed under a special foreach
loop, which will implement the waiting and retry logic.
foreach (var _ in EventualAssertions.Attempts(4.Seconds(), 400.Milliseconds()))
{
button.Should().BeVisible();
}
Source generator usage
When having a custom assertion class for a dynamic by nature subject the class can be decorated by the [GenerateEventual]
attribute to get a special waiting wrapper generated.
Your code (simplified):
[GenerateEventual]
public class ButtonAssertions
{
[CustomAssertion]
public AndConstraint<ButtonAssertions> BeVisible(string? because = null, params object[] becauseArgs)
{
// implementation
}
}
What gets generated (simplified):
public static class ButtonAssertions_Eventual_Extensions
{
public static ButtonAssertions_Eventual Eventually(this ButtonAssertions underlying) { /* ... */ }
// more generated extensions
}
public class ButtonAssertions_Eventual
{
// constructor, fields
[CustomAssertion]
public AndConstraint<ButtonAssertions> BeVisible(string? because = null, params object[] becauseArgs)
{
AndConstraint<CurrentDateTimeAssertions> result = default !;
foreach (var _ in EventualAssertions.Attempts(timeout, delay))
result = underlying.BeVisible(because, becauseArgs);
return result;
}
}
Which allows for the following syntax:
button.Should().Eventually().BeVisible();
button.Should().Eventually(4.Seconds(), 400.Milliseconds()).BeVisible();
button.Should().EventuallyLong().BeVisible();