Implement tests

[Git-Math]

Implement tests:

• Universe.step()
• Configuration.step()
• Universe.solve_interference()
• Universe.measure()
• get_cell_coordinates()
• Implement a function to check the validity of a rule "matrix"
• Maybe add tests to compute_rules()
• Maybe add tests to square_state_to_index()
• Maybe add tests to index_to_square_state()

[elhmn]

I tried to implement the tests but it quickly became a pain as every time I tried ran the test script, the application was entirely recompiled. The compilation took a while because of nannou dependencies that needed to be rebuild every time.

In #41 the project was splitted in workspaces. This will allow us to implement
tests exclusively for the core crate which does not have nannou as a dependency. The dev feedback loop should be smaller and writing tests will be more enjoyable.

[elhmn]

We have also decided to use the state_2_diagonal_cells.json file as the main test fixture.
This file will help us create test scenarios and snapshots that can be used to write every tests.

We will also be tracking the test coverage using the tools provided by the cargo llvm profiler and grcov.

You might need to install llvm-tools

rustup component add llvm-tools-preview

Generate coverage files

RUSTFLAGS='-Cinstrument-coverage' LLVM_PROFILE_FILE='cargo-test-%m.profraw' cargo test

Generate html page to visualise the coverage using grcov

grcov . --binary-path ./target/debug/deps/ -s . -t html --branch --ignore-not-existing --ignore '../*' --ignore "/*" -o target/coverage

Visualize the coverage

open ./target/coverage/html/index.html

This should open a nice web page with a nice test coverage report