Improve exercise generator (#1797)

- Add a clap-based CLI
  All user-input can now be entered upfront with cli flags
  or later by being prompted for it interactively.

- Limit output of rustfmt passed onto user
  (There are usually many duplicates when generating test cases.)

- Handle absence of canonical data
  (e.g. for custom exercises) not from problem-specifications)

piggyback:

- Make exercise difficulty in track config type-safe

docs/CONTRIBUTING.md

@@ -29,7 +29,7 @@ Please familiarize yourself with the [Exercism documentation about practice exer
 
 [Exercism documentation about practice exercises]: https://exercism.org/docs/building/tracks/practice-exercises
 
-Run `just add-practice-exercise` and you'll be prompted for the minimal
+Run `just add-exercise` and you'll be prompted for the minimal
 information required to generate the exercise stub for you.
 After that, jump in the generated exercise and fill in any todos you find.
 This includes most notably:
@@ -89,7 +89,7 @@ This includes their test suite and user-facing documentation.
 Before proposing changes here,
 check if they should be made `problem-specifications` instead.
 
-Run `just update-practice-exercise` to update an exercise.
+Run `just update-exercise` to update an exercise.
 This outsources most work to `configlet sync --update`
 and runs the test generator again.
 

justfile

@@ -17,13 +17,8 @@ test:
     cd rust-tooling && cargo test
     # TODO format exercises
 
-add-practice-exercise:
-    cd rust-tooling && cargo run --quiet --bin generate_exercise
+add-exercise *args="":
+    cd rust-tooling/generate; cargo run --quiet --release -- add {{ args }}
 
-update-practice-exercise:
-    cd rust-tooling && cargo run --quiet --bin generate_exercise update
-
-# TODO remove. resets result of add-practice-exercise.
-clean:
-    git restore config.json exercises/practice
-    git clean -- exercises/practice
+update-exercise *args="":
+    cd rust-tooling/generate; cargo run --quiet --release -- update {{ args }}

rust-tooling/Cargo.toml

@@ -1,3 +1,3 @@
 [workspace]
-members = ["generator", "ci-tests", "utils", "models"]
+members = ["generate", "ci-tests", "utils", "models"]
 resolver = "2"

rust-tooling/generator/Cargo.toml → rust-tooling/generate/Cargo.toml

@@ -1,12 +1,13 @@
 [package]
-name = "generator"
+name = "generate"
 version = "0.1.0"
 edition = "2021"
 description = "Generates exercise boilerplate, especially test cases"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+clap = { version = "4.4.8", features = ["derive"] }
 convert_case = "0.6.0"
 glob = "0.3.1"
 inquire = "0.6.2"