Zero-Allocation Testing -- Performance Enforcement

"Catch memory regressions before they hit production."

Industry First: Skugga is the only .NET mocking library providing allocation assertions to prove your hot paths are truly zero-allocation.

The Problem

You've optimized your code to avoid allocations, but how do you prove it stays that way?

// You think this is zero-allocation...
public string GetCacheKey(int userId, string resource)
{
    return $"user:{userId}:{resource}"; // Allocates!
}
// 1M requests/day x 80 bytes = 80 GB of garbage!

The Solution

Zero-Allocation Assertion

AssertAllocations.Zero(() => {
    cache.Lookup(key); // If this allocates, test FAILS
});

Allocation Budgets

AssertAllocations.AtMost(() => {
    ProcessRequest(data);
}, maxBytes: 1024); // Fail if > 1KB

Measurement & Comparison

var report = AssertAllocations.Measure(() => {
    for (int i = 0; i < 1000; i++) {
        GetCacheKey(i, "profile");
    }
}, "Cache Key Generation");

Console.WriteLine($"Allocated: {report.BytesAllocated:N0} bytes");
Console.WriteLine($"Gen0: {report.Gen0Collections}");
Console.WriteLine($"Gen1: {report.Gen1Collections}");

Real-World Examples

String Optimization

// Before: 50,000 bytes
var key = "user:" + userId + ":profile";

// After: 0 bytes
FormatCacheKey(stackAllocBuffer, userId);

LINQ vs Loops

// Before: 80,000 bytes (LINQ iterators + ToList)
var filtered = items.Where(x => x % 2 == 0).Select(x => x * 2).ToList();

// After: 4,000 bytes (pre-sized list, for-loop)
var result = new List<int>(500);
for (int i = 0; i < items.Count; i++)
    if (items[i] % 2 == 0) result.Add(items[i] * 2);

CI/CD Integration

[Fact]
public void HotPath_NoAllocationRegression()
{
    const long MaxAllowedBytes = 512; // Baseline

    var report = AssertAllocations.Measure(() => HotPath.Execute(input));

    Assert.True(
        report.BytesAllocated <= MaxAllowedBytes,
        $"Regression! Expected <= {MaxAllowedBytes}, got {report.BytesAllocated}"
    );
}

Comparison

Tool	Assertions	CI/CD	Zero Setup
Skugga	Yes	Yes	Yes
BenchmarkDotNet	No	Partial	No
PerfView	No	No	No
dotMemory	No	No	No

Full Allocation Testing guide | Demo code