Example Grader

This chapter will walk you through building a complete grader from start to finish. I'm writing this as I publish version 0.10.0. There will no doubt be changes in later versions.

Scenario

Let's say we wrote a lab to teach the basics of Git, and we need to ensure that the sudents have done the following:

• Installed Git
• Initialized Git in a repository
• Made at least 3 commits in the repository
• Pushed the repository to Github

These are our "criteria", which is an important term. Because we have 4 criteria, let's say each is worth 25 points for a total of 100 points.

Let's write a grader program that the student will run. The grader will check these criteria and send a report back to us.

Setup

Our grader will be written in Rust. Before we get started, be sure you have all the necessary tools to write a Rust application, including cargo. You can install it here if you don't already have it. Be sure you're running on the "nightly" release of Rust. You can switch to nightly with rustup default nightly.

We'll make a new Rust project using cargo

$ cargo new my_grader

This will make 3 files for us. Cargo.toml is where we specify details about our application (called a "crate"). You can leave most of it alone, as we won't be publishing this crate, but you need to add this crate (lab_grader) as a dependency.

[dependencies]
lab_grader = "0.10.0"

main.rs contains a hello world function, so you can go ahead and compile and run your program with

$ cargo run

After it compiles you should see "Hello, world!". Now we can move on to defining the criteria.