Track Driving History with Ruby

Objective

The objective of this project is to showcase my design and implementation of production quality code as a member of your development team.

Problem Statement

Let's write some code to track driving history for people.

The code will process an input file. You can either choose to accept the input via stdin (e.g. if you're using Ruby cat input.txt | ruby yourcode.rb), or as a file name given on the command line (e.g. ruby yourcode.rb input.txt). You can use any programming language that you want. Please choose a language that allows you to best demonstrate your programming ability.

Each line in the input file will start with a command. There are two possible commands.

The first command is Driver, which will register a new Driver in the app. Example:

Driver Dan

The second command is Trip, which will record a trip attributed to a driver. The line will be space delimited with the following fields: the command (Trip), driver name, start time, stop time, miles driven. Times will be given in the format of hours:minutes. We'll use a 24-hour clock and will assume that drivers never drive past midnight (the start time will always be before the end time). Example:

Trip Dan 07:15 07:45 17.3

Discard any trips that average a speed of less than 5 mph or greater than 100 mph.

Generate a report containing each driver with total miles driven and average speed. Sort the output by most miles driven to least. Round miles and miles per hour to the nearest integer.

Example input:

Driver Dan
Driver Lauren
Driver Kumi
Trip Dan 07:15 07:45 17.3
Trip Dan 06:12 06:32 21.8
Trip Lauren 12:01 13:16 42.0

Expected output:

Lauren: 42 miles @ 34 mph
Dan: 39 miles @ 47 mph
Kumi: 0 miles

Design Approach

My primary goal is to design the backend to avoid the classic phenomemum of Fat Models and God Classes.

Architected the software with separation of concerns in mind, resulting in a clear tier architecture, and a linear data flow. The code base is structured as follows:

• models: contain data only. No business logic
• models/factory/model_factory.rb: is the singleton model creator. Keeps data persistency
• services: provide the business logic as procedural static methods
• reports: provide the report generation as procedural static methods

Implementation

Below is a few stats of the code base.

Application LOC

$ find app -iname '*.rb' | xargs wc -l | grep total$
    206 total

Testing LOC

$ find spec -iname '*_spec.rb' | xargs wc -l | grep total$
    530 total

Test Coverage

There is 100% test coverage, see coverage/index.html for more details:

Run Program

Run program as follows:

ruby track_driving_history.rb input.txt

Note: This code was tested with Ruby 2.4.5

Unit Tests

Run unit tests as follows:

$ rspec