This is an exercise helping you to learn Test-Driven Development. Your task is to test-drive a function that filters, sorts and paginates a bunch of data. In this case the data concerns horses.

One of the challenges of this exercise is to design suitable test data. There is some sample data provided which you can use as a starting point. Feel free to modify it as needed.

There is also a sample test case provided which is a starting point, feel free to change it as you wish.

There is a function in the horse backend marked with 'TODO' statements. This function should filter, sort and paginate an arbitrary table of horse data, as specified. You can change anything about the code, except for the signature of this function. It will be called by a front-end component which expects exactly this signature.

Note on data size and performance:

• Assume the table data will have no more than 50 000 rows and 100 columns, and will easily fit into available memory space.
• Assume you will filter on a maximum of 100 columns
• Assume you will only sort on one column
• Assume the pagination is for page sizes of anything from 1 to 500 rows.

Use Test-Driven Development!

If your favourite programming language isn't present in this repository, please feel free to make a translation and send me a pull request. Alternatively, use the json below as a starting point.

I didn't want to include parsing json as part of the exercise since it's awkward to do in some languages, and isn't the main thing I want people to learn how to do. My focus is really on TDD, small steps, and particularly in this case, designing good test data. Having said that, the json is below if you prefer to start from there.

A request from the front end might look like this:

{
    "Filters": [{"ColumnHeader": "Breed", "Value": "Thoroughbred"}, 
                {"ColumnHeader": "Age", "Value": 2}],
    "Sorting": {"ColumnHeader": "Height", "SortOrder": "Descending"},
    "Pagination": {"FirstRecordInPage": 4, "PageSize": 3}
}

The table data you have in the back end and might look like this: (You should write code that would work with more columns and more rows).

{
    "Headers": ["Breed", "Colour", "Height", "Age", "Shoes"],
    "TableData": [["Thoroughbred", "Bay", 1.60, 3, true],
                  ["Thoroughbred", "Grey", 1.55, 3, true],
                  ["Arabian horse", "Bay", 1.51, 5, true],
                  ["Shetland Pony", "Black", 1.01, 2, false],
                  ["Shire horse", "Black", 1.71, 4, true]]
}

You should return data to the front end in this format:

{
    "Headers": ["Breed", "Colour", "Height", "Age", "Shoes"],
    "TableData": [["Thoroughbred", "Grey", "1.55", "3", "true"],
                  ["Arabian horse", "Bay", "1.51", "5", "true"],
                  ["Shetland Pony", "Black", "1.01", "2", "false"],
                  ["Shire horse", "Black", "1.71", "4", "true"]],
    "TotalRows": 6
}

"TotalRows" refers to the actual number of rows that exist in the back end that match the criteria, it will normally be larger than the number of rows in "TableData". The data should all be presented as strings, and satisfy the filter, sorting and pagination request. (Note, the data in this example doesn't do that. Part of the exercise is to come up with better test data).