Property based testing

[jpuriol]

I believe it would be beneficial to add property-based tests to some of the exercises. This would ensure that students provide correct answers even for unusual edge cases. Have you considered this approach? I've already added property-based tests to the circular buffer exercise but am unsure how to contribute further.

[github-actions]

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[ErikSchierboom]

We have two such exercises:

• diamond
• hyperia forex

[jpuriol]

Do you think these tests will improve the Circular Buffer exercise? I personally feel more confident about my implementation after running them, but I'm uncertain whether they cover more scenarios than the example-based tests. If you believe they add value, I can create a pull request to include them.

[Property]
public void WriteAndRead_ShouldWorkCorrectly(int capacity, int[] values)
{
    if (capacity <= 0 || values == null) return;

    var buffer = new CircularBuffer<int>(capacity);

    foreach (var value in values)
    {
        buffer.Write(value);
        Assert.Equal(value, buffer.Read());
    }
}

[Property]
public void WriteBeyondCapacity_ShouldThrowException(int capacity, int[] values)
{
    if (capacity <= 0 || values == null) return;

    var buffer = new CircularBuffer<int>(capacity);

    foreach (var value in values)
    {
        if (buffer.Size < capacity)
        {
            buffer.Write(value);
        }
        else
        {
            Assert.Throws<InvalidOperationException>(() => buffer.Write(value));
        }
    }
}

[Property]
public void ReadFromEmptyBuffer_ShouldThrowException(int capacity)
{
    if (capacity <= 0) return;

    var buffer = new CircularBuffer<int>(capacity);
    Assert.Throws<InvalidOperationException>(() => buffer.Read());
}

[Property]
public void Overwrite_ShouldReplaceOldestValue(int capacity, int[] values)
{
    if (capacity <= 0 || values == null) return;

    var buffer = new CircularBuffer<int>(capacity);

    foreach (var value in values)
    {
        buffer.Overwrite(value);
    }

    for (int i = Math.Max(0, values.Length - capacity); i < values.Length; i++)
    {
        Assert.Equal(values[i], buffer.Read());
    }
}

[Property]
public void Clear_ShouldResetBuffer(int capacity, int[] values)
{
    if (capacity <= 0 || values == null) return;

    var buffer = new CircularBuffer<int>(capacity);

    foreach (var value in values)
    {
        if (buffer.Size < capacity)
        {
            buffer.Write(value);
        }
    }

    buffer.Clear();
    Assert.Throws<InvalidOperationException>(() => buffer.Read());
}

[ErikSchierboom]

Personally, I really like property-based tests, but in this case I think the existing test cases cover these scenarios well enough.