Sample Coding Test (561 words)

Being in the job market again I been doing quite a few tests. Since I have already put in the effort to a test without result I thought I would post it here.

The test involved producing output from a supplied CSV input file which contained insurance claims. Something about taking the input and using it to predict future claims. Please forgive my explanation as I am not a financial expert. Anyway the idea was to take an input such as the following,

Header
One, 1992, 1992, 110.0
One, 1992, 1993, 170.0
One, 1993, 1993, 200.0
Two, 1990, 1990, 45.2
Two, 1990, 1991, 64.8
Two, 1990, 1993, 37.0
Two, 1991, 1991, 50.0
Two, 1991, 1992, 75.0
Two, 1991, 1993, 25.0
Two, 1992, 1992, 55.0
Two, 1992, 1993, 85.0
Two, 1993, 1993, 100.0

into the following,

1990, 4
One, 0, 0, 0, 0, 0, 0, 0, 110, 280, 200
Two, 45.2, 110, 110, 147, 50, 125, 150, 55, 140, 100

The test was mostly about proving that you can write maintainable code which is unit testable and the like. Anyway here is my solution. It takes in a list of objects which represent each of the four columns of the input.

The feedback I received back was that the coverage I achieved was high (I had a collection of tests over the methods), the code clean and well documented.

public class TriangleCSVLine
{
    public string product { get; set; }
    public int originYear { get; set; }
    public int developmentYear { get; set; }
    public double incrementalValue { get; set; }
}

public List<string> TranslateToOutput(List<TriangleCSVLine> parsedCsv)
{
    var output = new List<string>();

    // Sanity checks...
    if (parsedCsv == null || parsedCsv.Count == 0)
    {
        return output;
    }
    output.Add(GenerateHeader(parsedCsv));

    // Used to determine where we are looking
    var totalYears = parsedCsv.Select(x => x.developmentYear).Distinct().OrderBy(x => x);
    var minYear = totalYears.Min();
    var maxYear = totalYears.Max();

    foreach (var product in parsedCsv.Select(x => x.product).Distinct())
    {
        // All of the products values and the years it has
        var productValues = parsedCsv.Where(x => product.Equals(x.product));
        var originYears = Enumerable.Range(minYear, (maxYear - minYear) + 1);

        var values = new List<double>();

        foreach (var year in originYears)
        {
            // For each of the development years for this "period"
            var developmentYears = parsedCsv.Where(x => x.originYear == year)
                                                .Select(x => x.developmentYear).Distinct();

            // If we have no development years
            // that means we have an origin year without a year 1 
            // development year. This means we have no idea how many values
            // of zero should be in the file, so lets bail
            // should probably go into a pre validation
            if (developmentYears.Count() == 0)
            {
                throw new MissingOriginDevelopmentTrangleCSVException(
                    string.Format("Missing development years for origin {0} in product {1}", year, product)
                );
            }

            // The values are running values...
            // so we keep the total and increment it as we go
            double runningTotal = 0;
            foreach (var rangeYear in Enumerable.Range(developmentYears.Min(), (developmentYears.Max() - developmentYears.Min()) + 1))
            {
                var value1 = productValues.Where(x => x.originYear == year && x.developmentYear == rangeYear).SingleOrDefault();
                if (value1 != null)
                {
                    runningTotal += value1.incrementalValue;
                }
                values.Add(runningTotal);
            }
                    
        }
        output.Add(string.Format("{0}, {1}", product, string.Join(", ", values)));
    }

    return output;
}

private string GenerateHeader(List<TriangleCSVLine> parsedCsv)
{
    // Get distinct list of all the years
    var years = parsedCsv.Select(x => x.developmentYear).Distinct();

    // 1990-1990 counts as 1 year so add one
    var developmentYears = (years.Max() - years.Min()) + 1; 
    var header = string.Join(", ", years.Min(), developmentYears);

    return header;
}