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NCBC-4279: Stop unit tests asserting exact sizes on pooled buffers #158

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NCBC-4279: Stop unit tests asserting exact sizes on pooled buffers #158

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42 changes: 26 additions & 16 deletions tests/Couchbase.UnitTests/Core/IO/Operations/OperationBuilderTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -494,74 +494,84 @@ private void EnsureCapacity_Zero_NoChange()
Assert.Equal(currentCapacity, builder.Capacity);
}

// The growth tests below assert an inequality. EnsureCapacity rents from ArrayPool and
// promises only that the buffer is at least as large as requested; any doubling is the
// pool's bucket rounding, not something OperationBuilder implements. Asserting an exact
// size makes these depend on pool internals, which on .NET Framework overshoot to a larger
// bucket when the requested one is exhausted.

[Fact]
private void EnsureCapacity_OneMore_Doubles()
private void EnsureCapacity_OneMore_Grows()
{
// Arrange

using var builder = new OperationBuilder();
var currentCapacity = builder.Capacity;
var requested = builder.Capacity + 1;

// Act

builder.EnsureCapacity(currentCapacity + 1);
builder.EnsureCapacity(requested);

// Assert

Assert.Equal(currentCapacity * 2, builder.Capacity);
AssertAtLeast(requested, builder.Capacity);
}

[Fact]
private void EnsureCapacity_Double_Doubles()
private void EnsureCapacity_Double_Grows()
{
// Arrange

using var builder = new OperationBuilder();
var currentCapacity = builder.Capacity;
var requested = builder.Capacity * 2;

// Act

builder.EnsureCapacity(currentCapacity * 2);
builder.EnsureCapacity(requested);

// Assert

Assert.Equal(currentCapacity * 2, builder.Capacity);
AssertAtLeast(requested, builder.Capacity);
}

[Fact]
private void EnsureCapacity_OneMoreThanDouble_Quadruples()
private void EnsureCapacity_OneMoreThanDouble_Grows()
{
// Arrange

using var builder = new OperationBuilder();
var currentCapacity = builder.Capacity;
var requested = builder.Capacity * 2 + 1;

// Act

builder.EnsureCapacity(currentCapacity * 2 + 1);
builder.EnsureCapacity(requested);

// Assert

Assert.Equal(currentCapacity * 4, builder.Capacity);
AssertAtLeast(requested, builder.Capacity);
}

[Fact]
private void EnsureCapacity_Quadruple_Quadruples()
private void EnsureCapacity_Quadruple_Grows()
{
// Arrange

using var builder = new OperationBuilder();
var currentCapacity = builder.Capacity;
var requested = builder.Capacity * 4;

// Act

builder.EnsureCapacity(currentCapacity * 4);
builder.EnsureCapacity(requested);

// Assert

Assert.Equal(currentCapacity * 4, builder.Capacity);
AssertAtLeast(requested, builder.Capacity);
}

private static void AssertAtLeast(int requested, int actualCapacity) =>
Assert.True(actualCapacity >= requested,
$"Expected a capacity of at least {requested}, found {actualCapacity}.");

#endregion

#region Helpers
Expand Down
18 changes: 12 additions & 6 deletions tests/Couchbase.UnitTests/Utils/SlicedMemoryOwnerTests.cs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,4 @@
using System;
using System.Buffers;
using System.Linq;
using Couchbase.UnitTests.Helpers;
using Couchbase.Utils;
Expand All @@ -9,6 +8,13 @@ namespace Couchbase.UnitTests.Utils
{
public class SlicedMemoryOwnerTests
{
// These tests use FakeMemoryOwner rather than MemoryPool<byte>.Shared.Rent, because Rent
// only promises *at least* the requested size. On .NET Framework the pool falls back to a
// larger bucket when the requested one is exhausted, so a Rent(32) under load returns 64
// and every assertion below that depends on the buffer being exactly 32 bytes fails.
private static FakeMemoryOwner<byte> ExactlySized(int length) =>
new FakeMemoryOwner<byte>(new byte[length]);

#region ctor1

[Fact]
Expand All @@ -27,7 +33,7 @@ public void ctor1_NullMemoryOwner_ArgumentNullException()
public void ctor1_StartOutsideRange_ArgumentOutOfRangeException(int start)
{
// Act/Assert
using (var memory = MemoryPool<byte>.Shared.Rent(32))
using (var memory = ExactlySized(32))
{
Assert.Throws<ArgumentOutOfRangeException>(() => new SlicedMemoryOwner<byte>(memory, start));
}
Expand All @@ -40,7 +46,7 @@ public void ctor1_StartOutsideRange_ArgumentOutOfRangeException(int start)
public void ctor1_StartWithinRange_SliceUntilEnd(int start, int expectedLength)
{
// Act/Assert
using (var memory = new SlicedMemoryOwner<byte>(MemoryPool<byte>.Shared.Rent(32), start))
using (var memory = new SlicedMemoryOwner<byte>(ExactlySized(32), start))
{
Assert.Equal(expectedLength, memory.Memory.Length);
}
Expand Down Expand Up @@ -82,7 +88,7 @@ public void ctor2_NullMemoryOwner_ArgumentNullException()
public void ctor2_NegativeStart_ArgumentOutOfRangeException()
{
// Act/Assert
using (var memory = MemoryPool<byte>.Shared.Rent(32))
using (var memory = ExactlySized(32))
{
Assert.Throws<ArgumentOutOfRangeException>(() => new SlicedMemoryOwner<byte>(memory, -1, 10));
}
Expand All @@ -96,7 +102,7 @@ public void ctor2_NegativeStart_ArgumentOutOfRangeException()
public void ctor2_StartOutsideRange_ArgumentOutOfRangeException(int start)
{
// Act/Assert
using (var memory = MemoryPool<byte>.Shared.Rent(32))
using (var memory = ExactlySized(32))
{
Assert.Throws<ArgumentOutOfRangeException>(() => new SlicedMemoryOwner<byte>(memory, start, 1));
}
Expand All @@ -109,7 +115,7 @@ public void ctor2_StartOutsideRange_ArgumentOutOfRangeException(int start)
public void ctor2_StartWithinRange_SliceLength(int start, int length)
{
// Act/Assert
using (var memory = new SlicedMemoryOwner<byte>(MemoryPool<byte>.Shared.Rent(32), start, length))
using (var memory = new SlicedMemoryOwner<byte>(ExactlySized(32), start, length))
{
Assert.Equal(length, memory.Memory.Length);
}
Expand Down
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