Use 'ArgumentOutOfRangeException.ThrowIfNegative' instead of explicitly throwing a new exception instance (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1512)

Use recommended dispose pattern to ensure that object created by 'new DummyFileWriter(filepathToCreate, bufferSize)' is disposed on all paths. If possible, wrap the creation within a 'using' statement or a 'using' declaration. Otherwise, use a try-finally pattern, with a dedicated local variable declared before the try region and an unconditional Dispose invocation on non-null value in the 'finally' region, say 'x?.Dispose()'. If the object is explicitly disposed within the try region or the dispose ownership is transfered to another object or method, assign 'null' to the local variable just after such an operation to prevent double dispose in 'finally'. (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca2000)

Test methods should not call ConfigureAwait(false), as it may bypass parallelization limits. Omit ConfigureAwait, or use ConfigureAwait(true) to avoid CA2007. (https://xunit.net/xunit.analyzers/rules/xUnit1030)

Test methods should not call ConfigureAwait(false), as it may bypass parallelization limits. Omit ConfigureAwait, or use ConfigureAwait(true) to avoid CA2007. (https://xunit.net/xunit.analyzers/rules/xUnit1030)

Test methods should not call ConfigureAwait(false), as it may bypass parallelization limits. Omit ConfigureAwait, or use ConfigureAwait(true) to avoid CA2007. (https://xunit.net/xunit.analyzers/rules/xUnit1030)

Test methods should not call ConfigureAwait(false), as it may bypass parallelization limits. Omit ConfigureAwait, or use ConfigureAwait(true) to avoid CA2007. (https://xunit.net/xunit.analyzers/rules/xUnit1030)

Test methods should not call ConfigureAwait(false), as it may bypass parallelization limits. Omit ConfigureAwait, or use ConfigureAwait(true) to avoid CA2007. (https://xunit.net/xunit.analyzers/rules/xUnit1030)

Test methods should not call ConfigureAwait(false), as it may bypass parallelization limits. Omit ConfigureAwait, or use ConfigureAwait(true) to avoid CA2007. (https://xunit.net/xunit.analyzers/rules/xUnit1030)

Dereference of a possibly null reference.