Software Engineer Technical Test

This technical test consists of two parts, one covering PHP, and the other covering SQL.

Part 1: PHP

The puzzle

A man is trying to visit his friend in a large apartment building, but he can't find the right floor - the directions he got are a little confusing. He starts on the ground floor (floor 0) and then follows the instructions one character at a time.

An opening parenthesis, (, means he should go up one floor, and a closing parenthesis, ), means he should go down one floor. Any other characters in the instructions should be ignored.

The apartment building is very tall, and the basement is very deep; he will never find the top or bottom floors.

He needs you to help him work out which floor his friend lives on.

The solution

We have created a PHP class Solution in src/Part1/Solution.php. This class takes an instruction set as a string in its constructor, and has a single method getAnswer(). The method is not implemented.

Implement the getAnswer() method; it should return the floor number, as an int, that the instruction set will lead to.

We encourage you to use an object-oriented solution. Although we have included a Solution class in this repository, you can add other classes and/or functions as necessary in order to come up with a solution.

The solution should work for any set of input instructions (i.e. any combination of ( and ) characters).

We have provided a set of sample instruction sets in input/, and a test that uses each of these sample instruction sets.

Do not remove or change SolutionTest. We encourage you to add unit tests for any other classes or functions that you create.

Part 2: SQL

The data

We have a collection of tables for a music library application. The tables are as follows:

|----------- ARTISTS -----------|
| id (INTEGER) | name (VARCHAR) |
|--------------|----------------|
| 1            | The Beatles    |
|--------------|----------------|
| 2            | Nirvana        |
|--------------|----------------|
| ...          | ...            |
|--------------|----------------|

|----------- SONGS --------------------------------------------|
| id (INTEGER) | title (VARCHAR)         | artist_id (INTEGER) |
|--------------|-------------------------|---------------------|
| 1            | Come Together           | 1                   |
|--------------|-------------------------|---------------------|
| 2            | Smells Like Teen Spirit | 2                   |
|--------------|-------------------------|---------------------|
| ...          | ...                     | ...                 |
|--------------|-------------------------|---------------------|

|----------- GENRES ------------|
| id (INTEGER) | name (VARCHAR) |
|--------------|----------------|
| 1            | Pop            |
|--------------|----------------|
| 2            | Rock           |
|--------------|----------------|
| ...          | ...            |
|--------------|----------------|

|------------- SONGS_GENRES -------------|
| song_id (INTEGER) | genre_id (INTEGER) |
|-------------------|--------------------|
| 1                 | 1                  |
|-------------------|--------------------|
| 1                 | 2                  |
|-------------------|--------------------|
| 2                 | 2                  |
|-------------------|--------------------|
| 2                 | 3                  |
|-------------------|--------------------|
| ...               | ...                |
|-------------------|--------------------|

The solution

We have created a PHP class Solution in src/Part2/Solution.php. There are two methods in this class, artistAndSongTitleSQL and artistsWithMultipleGenresSQL. These methods are not yet implemented.

1. Implement the artistAndSongTitleSQL() method; it should return the appropriate SQL to select the artist name and song title for every song in the dataset. Fill in the return statement provided with your SQL SELECT statement.

2. Implement the artistsWithMultipleGenresSQL method; it should return the appropriate SQL to select those artists who have MULTIPLE (>1) genres in the dataset along with the number of genres they have.

• The tests use an in-memory SQLite database filled with data. You can explore the data in schema/data.sql.
• You should not need to change anything in Solution except to add your SQL.
• The bundled test suite should not be changed (although you may add more tests if you want).
• The test suite must pass.

Instructions

• Fork this repository and clone it.
• Implement your solution in src/Part1/Solution.php and src/Part2/Solution.php. Remember, you can add more PHP classes and functions if you want to. You can do this in the src/ directory.
• Commit your solution and push to your fork.
• Submit a pull request to our repository ahead of your scheduled interview.

Running the tests

The tests will run automatically any time you push, using GitHub Actions. You can verify that the tests pass for your solution by visiting your GitHub repository homepage, then clicking Actions at the top of the page.

Running the tests locally (on your computer)

We have deliberately designed this puzzle so that you do not need to run the tests locally to demonstrate that you have solved it. However, it is of course possible by following these steps:

• You will need an environment with PHP 8.1, and Composer.
• Install dependencies with composer install.
• Run tests with vendor/bin/phpunit.