/// <summary>Creates a concrete arg type from the given generic arg.</summary>
/// <param name="type">Generic arg to create.</param>
/// <returns>Created arg type.</returns>
private Type CreateArg(Type type)
{
bool newNeeded = type.GenericParameterAttributes.HasFlag(
GenericParameterAttributes.DefaultConstructorConstraint);
Type arg;
if (type.GenericParameterAttributes.HasFlag(
GenericParameterAttributes.NotNullableValueTypeConstraint))
{
arg = _gen.NextItem(ValueRandom.ValueTypes);
}
else if (newNeeded)
{
arg = typeof(object);
}
else
{
arg = typeof(string);
}
Type[] constraints = type.GetGenericParameterConstraints();
Limiter.Dozen.Repeat(() =>
{
while (!constraints.All(c => arg.Inherits(c)) &&
(!newNeeded || arg.GetConstructor(Type.EmptyTypes) != null))
{
arg = _randomizer.Create(_gen.NextItem(constraints)).GetType();
}
}).Wait();
return(arg);
}
/// <inheritdoc/>
public object Variant(Type type, object instance, params object[] extraInstances)
{
IEnumerable <object> values = (extraInstances ?? Enumerable.Empty <object>()).Prepend(instance);
object result = default;
try
{
_limiter.StallUntil(
() => result = _randomizer.Create(type),
() => values.All(o => !_valuer.Equals(result, o))).Wait();
}
catch (AggregateException e)
{
throw new TimeoutException($"Could not create different instance of type '{type}'.", e);
}
return(result);
}