public async Task GetAsync_WhenRepositoryIsNull_ThrowsArgumentNullException <TEntity, TKey>(
TKey defaultKey,
TEntity entity,
Expression <Func <TEntity, bool> > filterExpression)
where TEntity : class, IEntity <TKey>
{
// Arrange & Act & Assert
var exception = await Assert.ThrowsAsync <ArgumentNullException>(
() => RepositoryExtensions.GetAsync <TEntity, TKey>(null, filterExpression)
);
if (entity != null && entity.Id != null)
{
Assert.IsType(defaultKey.GetType(), entity.Id);
}
Assert.Equal("repository", exception.ParamName);
}