How to Mock FeatureFilterEvaluationContext Parameters?

Question

I created a custom feature filter and in EvaluateAsync I get the feature flag's custom settings from Azure's Feature manager for this specific feature flag's filter.

public virtual Task<Boolean> EvaluateAsync(FeatureFilterEvaluationContext context)
{
    _settings = context.Parameters.Get<IdFilterSettings>();

Where IdFilterSettings looks like this:

internal class IdFilterSettings
{
    public String[]? AllowedIds { get; set; }
    public String[]? BlockedIds { get; set; }
}

When calling it through an actual API call, _settings properly gets set to a new instance of IdFilterSettings with AllowedIds and BlockedIds properly populated.

But, when I try to unit test this and mock FeatureFilterEvaluationContext with this code:

var allowedIds = new string[2] { "someId1", "someId2" };
var blockedIds = new string[1] { "someId3" };
var parameters = new Dictionary<string, string?>
{
    { "AllowedIds", JsonSerializer.Serialize(allowedIds) },
    { "BlockedIds", JsonSerializer.Serialize(blockedIds) }
};
var context = new FeatureFilterEvaluationContext
{
    Parameters = new ConfigurationBuilder().AddInMemoryCollection(parameters).Build()
};

_filter = new CustomIdFilter(_httpContextAccessor.Object);

var result = await _filter.EvaluateAsync(context);

If I put a break point after _settings = context.Parameters.Get<IdFilterSettings>();, settings is a new instance of IdFilterSettings, but AllowedIds and BlockedIds are both null.

Answer 1

As per jimmyca15's answer here, I had to alter the parameters Dictionary to be:

var parameters = new Dictionary<string, string?>
{
    { "AllowedIds:0", "someId1" },
    { "AllowedIds:1", "someId2" },
    { "BlockedIds:0", "someId3" }
};