SingleResponsibilityPrinciple_Violation.cs

public class Sensor
{
    public string Name { get; }
    public List<double> MeasuredValues { get; }
    public double AverageValue
       => MeasuredValues.Average();
    public double MinimumValue
        => MeasuredValues.Min();
    public double MaximumValue
        => MeasuredValues.Max();

    public Sensor(string name, IEnumerable<double> measuredValues)
    {
        Name = name;
        MeasuredValues = new List<double>(measuredValues);
    }

    public void SaveToReportFile(string reportFile) 
        => SaveReportToFile(reportFile, ToFileContent());

    private void SaveReportToFile(string reportFile, string fileContent)
    {
        using (var fileStream = new FileStream(reportFile, FileMode.OpenOrCreate, FileAccess.Write))
        {
            using (var streamWriter = new StreamWriter(fileStream))
            {
                streamWriter.Write(fileContent);
            }
        }
    }

    private string ToFileContent()
    {
        var fileContent =
            $"#SensorInfo#Name:{Name};Average:{AverageValue};"
            + $"Minimum:{MinimumValue};Maximum:{MaximumValue}";

        MeasuredValues.ForEach(
                value => fileContent += $@"{Environment.NewLine}##{value}"
            );

        return fileContent;
    }
}