public void TheRequestedNumberOfTokensDepletesTheTokenBucket()
{
// Given
const int Interval = 10;
const int AverageRate = 2;
const int Bursting = 2;
const int Requested = 4;
const int Capacity = AverageRate * Bursting;
var tokenBucket = new TokenBucket.TokenBucket(
interval: Interval,
averageRate: AverageRate,
bursting: Bursting);
// When the number of tokens requested depletes the token bucket
var response = tokenBucket.Consume(Requested);
// Then it should allow token consumption
response.IsAllowed.Should().BeTrue();
response.Limit.Should().Be(Capacity);
response.Remaining.Should().Be(Capacity - Requested);
// And it should return the expected number of available tokens
response.Remaining.Should().Be(AverageRate * Bursting - Requested);
}
public void TheTokenConsumptionRateDoesNotBurstAboveCapacityInAnInterval()
{
// Given
const int Interval = 1;
const int AverageRate = 2;
const int Bursting = 2;
const int Requested = 1;
var response = new List <ConsumeResult>();
var tokenBucket = new TokenBucket.TokenBucket(
interval: Interval,
averageRate: AverageRate,
bursting: Bursting);
// Do not burst above average rate
response.Add(tokenBucket.Consume(Requested));
response.Add(tokenBucket.Consume(Requested));
var lastConsumedAt = DateTimeOffset.UtcNow.ToUnixTimeSeconds();
// Wait for interval to lapse
Thread.Sleep(Interval * 1000);
// When another token is consumed
response.Add(tokenBucket.Consume(Requested));
var availableTokensAfterBurst = (DateTimeOffset.UtcNow.ToUnixTimeSeconds() - lastConsumedAt) / Interval * AverageRate;
// Then it should return the expected sequence of responses
var capacityAtBurst = AverageRate * Bursting;
response[0].IsAllowed.Should().BeTrue();
response[0].Limit.Should().Be(capacityAtBurst);
response[0].Remaining.Should().Be(capacityAtBurst - 1);
response[1].IsAllowed.Should().BeTrue();
response[1].Limit.Should().Be(capacityAtBurst);
response[1].Remaining.Should().Be(capacityAtBurst - 2);
response[2].IsAllowed.Should().BeTrue();
response[2].Limit.Should().Be(capacityAtBurst);
response[2].Remaining.Should().Be(capacityAtBurst - 1);
}
public void TheRequestedNumberOfTokensExceedsAvailableTokens()
{
// Given
const int Interval = 10;
const int AverageRate = 2;
const int Bursting = 2;
const int Requested = 10;
const int Capacity = AverageRate * Bursting;
var tokenBucket = new TokenBucket.TokenBucket(
interval: Interval,
averageRate: AverageRate,
bursting: Bursting);
// When a token is consumed exceeding available capacity
var response = tokenBucket.Consume(Requested);
// Then it should not allow token consumption
response.IsAllowed.Should().BeFalse();
response.Limit.Should().Be(Capacity);
response.Remaining.Should().Be(Capacity);
}