Reject non-positive lengths in RingBuffer<T>

Containers.Test/RingBufferTests.cs

@@ -259,4 +259,53 @@ public void Clear_AllowsReuseAfterClearing()
 		Assert.AreEqual(1, buffer.Count);
 		Assert.AreEqual(7, buffer.At(0));
 	}
+
+	[TestMethod]
+	public void Constructor_NonPositiveLength_Throws()
+	{
+		Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => new RingBuffer<int>(0));
+		Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => new RingBuffer<int>(-1));
+	}
+
+	[TestMethod]
+	public void Constructor_PrefillValue_NonPositiveLength_Throws()
+	{
+		Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => new RingBuffer<int>(42, 0));
+		Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => new RingBuffer<int>(42, -1));
+	}
+
+	[TestMethod]
+	public void Constructor_PrefillItems_NonPositiveLength_Throws()
+	{
+		int[] items = [1, 2, 3];
+		Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => new RingBuffer<int>(items, 0));
+		Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => new RingBuffer<int>(items, -1));
+	}
+
+	[TestMethod]
+	public void Resize_NonPositiveLength_Throws()
+	{
+		RingBuffer<int> buffer = new(3);
+		Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => buffer.Resize(0));
+		Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => buffer.Resize(-1));
+	}
+
+	[TestMethod]
+	public void Resample_NonPositiveLength_Throws()
+	{
+		RingBuffer<int> buffer = new(3);
+		buffer.PushBack(1);
+		Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => buffer.Resample(0));
+		Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => buffer.Resample(-1));
+	}
+
+	[TestMethod]
+	public void Constructor_MinimumLength_IsUsable()
+	{
+		RingBuffer<int> buffer = new(1);
+		buffer.PushBack(1);
+		buffer.PushBack(2);
+		Assert.AreEqual(1, buffer.Count);
+		Assert.AreEqual(2, buffer.At(0));
+	}
 }

Containers/RingBuffer.cs

@@ -78,6 +78,7 @@ public class RingBuffer<T> : IReadOnlyList<T>
 	/// Initializes a new instance of the <see cref="RingBuffer{T}"/> class with the specified length.
 	/// </summary>
 	/// <param name="length">The number of elements the buffer should store.</param>
+	/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="length"/> is less than one.</exception>
 	public RingBuffer(int length) => AllocateBuffer(length);
 
 	/// <summary>
@@ -86,6 +87,7 @@ public class RingBuffer<T> : IReadOnlyList<T>
 	/// </summary>
 	/// <param name="items">The items to prefill the buffer with.</param>
 	/// <param name="length">The number of elements the buffer should store.</param>
+	/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="length"/> is less than one.</exception>
 	public RingBuffer(IEnumerable<T> items, int length)
 		: this(length)
 	{
@@ -111,6 +113,7 @@ public RingBuffer(IEnumerable<T> items, int length)
 	/// </summary>
 	/// <param name="value">The value to prefill the buffer with.</param>
 	/// <param name="length">The number of elements the buffer should store.</param>
+	/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="length"/> is less than one.</exception>
 	public RingBuffer(T value, int length)
 		: this(length)
 	{
@@ -124,8 +127,11 @@ public RingBuffer(T value, int length)
 	/// Allocates and initializes the internal buffer with the specified length.
 	/// </summary>
 	/// <param name="length">The number of elements to allocate space for.</param>
+	/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="length"/> is less than one.</exception>
 	private void AllocateBuffer(int length)
 	{
+		ArgumentOutOfRangeException.ThrowIfNegativeOrZero(length);
+
 		Length = length;
 		Capacity = NextPower2(Length);
 		Buffer = new T[Capacity];
@@ -218,6 +224,7 @@ private static int NextPower2(int v)
 	/// Resizes the buffer to the specified length, discarding all current contents.
 	/// </summary>
 	/// <param name="length">The new length of the buffer.</param>
+	/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="length"/> is less than one.</exception>
 	public void Resize(int length) => AllocateBuffer(length);
 
 	/// <summary>
@@ -234,6 +241,7 @@ private static int NextPower2(int v)
 	/// If the buffer is empty, this method will resize the buffer without adding any elements.
 	/// </remarks>
 	/// <param name="length">The new length of the buffer.</param>
+	/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="length"/> is less than one.</exception>
 	public void Resample(int length)
 	{
 		// Save the current count of valid elements