Programming Exercise

This repository contains a skeleton application to be used as part of the MindLink software development interview.

Application

Overview

This application is meant to read a conversation from a plain text file and output the conversation as JSON.

We are looking for the application to be fixed so that it works as intended and extended to support the functionality described below.

Features

• A user can export a conversation from a given file path stored in the following file format into a JSON file at the given output path:

<conversation_name><new_line>
(<unix_timestamp><space><username><space><message><new_line>)*

• Messages can be filtered by a specific user
  • The user can be provided as a command-line argument --filterByUser=<user>
  • All messages sent by the specified user appear in the JSON output
  • Messages sent by any other user do not appear in the JSON output
• Messages can be filtered by a specific keyword
  • The keyword can be specified as a command-line argument --filterByKeyword=<keyword>
  • All messages sent containing the keyword appear in the JSON output
  • Messages sent that do not contain the keyword do not appear in the JSON output
• Hide specific words
  • A blacklist can be specified as a command-line argument --blacklist=<word1> --blacklist=<word2>
  • Any blacklisted word is replaced with "*redacted*" in the JSON output.
• Include a report of the number of messages each user sent
  • Adding the report to the output can be specified as a command-line argument --report
  • The report is sorted in descending order of number of messages sent
  • The report should appear in the final JSON output under the activity property:

  {
   "name": "...",
   "messages": [...],
   "activity": [
      {
          "sender": "...",
          "count": 100
      },
      ...]
  }
  

Building and running

• This solution uses maven (https://maven.apache.org/users/index.html), feel free to change it to a different build solution.

• Command line with the Java SDK and Maven

  • To build everything
    • ./build.cmd from within the solution directory
    • OR mvn package from within the solution directory
  • To run the application
    • ./run.cmd from within the solution directory
    • OR java -jar target/my-chat-1.0-SNAPSHOT.jar -i <input> -o <output> from within the solution directory
  • To run the unit tests
    • ./test.cmd from within the solution directory
    • OR mvn clean test from within the solution directory

• IntelliJ Idea should detect the maven project and work as-is

Dependencies

• picocli (https://picocli.info/) - used to parse the command line
• Google gson (https://github.com/google/gson) - used to read and write JSON
• JUnit 4 (https://junit.org/junit4/) - used for unit testing

Instructions

1. Think about your architecture, maybe even sketch out a UML diagram!

2. Fork the repository into your own GitHub area

3. Install the Java 8 (or above) SDK from https://www.oracle.com/java/technologies/javase-downloads.html or if you prefer you can download the Open JDK from https://developers.redhat.com/products/openjdk/download

4. Download Maven from https://maven.apache.org/users/index.html, extract it somewhere and add it to your environment PATH for easy access (follow the maven usage instructions)

5. Identify and fix the existing issue

6. Make whatever changes you feel are necessary, it's your code now!

7. Make sure all features are implemented, the code works and all the tests you wrote pass!

8. When you are satisfied, submit back via a pull request. See details on GitHub's Fork & Pull model

9. Notify our recruitment team at careers <at> mindlinksoft.com with a link to your pull request and your real name ;)

What we are looking for

• Application of SOLID principles - https://en.wikipedia.org/wiki/SOLID

  • Imagine that there are another 20 features to implement, design with that in mind!
  • DON'T put everything in one method/one class
  • DO think about abstractions and commonality between features
  • DO think about separating concerns (IO vs business logic vs configuration and command line)

• A well-formed exception model

  • DON'T throw new Exception("non-descript message here")
  • DO throw appropriate exceptions e.g. is an argument null and shouldn't be? IllegalArgumentException then!
  • DO create and throw your own exception types when it makes sense
  • DO include inner exceptions, otherwise you lose your stack!

• Tidy code

  • Well named variables and methods
  • Consistent style

• Application of appropriate design patterns

  • There is scope to approach this challenge in different ways and design patterns can help you!

• Unit tests

  • DO write tests!
  • DO isolate your units under test (you don't need to read and write the file to test filtering behaviour if you have designed it well!)
  • DO include some end-to-end tests