testsuite: add rust generator test

This would have caught a failure on DMOJ#1148.

testsuite/rust_generator/README.md

@@ -0,0 +1 @@
+This test checks that a generator, using rand, can be compiled and run in Rust.

testsuite/rust_generator/generator.rs

@@ -0,0 +1,14 @@
+use rand::{Rng, SeedableRng};
+
+type ConcreteRng = rand_xoshiro::Xoshiro256PlusPlus;
+
+fn main() {
+    let mut args = std::env::args();
+    args.next();
+    let mut rng = ConcreteRng::seed_from_u64(args.next().unwrap().parse().unwrap());
+
+    let x = rng.gen_range(0..10);
+    let y = rng.gen_range(0..10);
+    println!("{x} {y}");
+    eprintln!("{}", x + y);
+}

testsuite/rust_generator/init.yml

@@ -0,0 +1,5 @@
+generator: generator.rs
+test_cases:
+- {generator_args: [1], points: 10}
+- {generator_args: [2], points: 10}
+- {generator_args: [3], points: 30}

testsuite/rust_generator/tests/AC/sol.py

@@ -0,0 +1,2 @@
+x, y = map(int, input().split())
+print(x + y)

testsuite/rust_generator/tests/AC/test.yml

@@ -0,0 +1,5 @@
+language: PY3
+time: 2
+memory: 65536
+source: sol.py
+expect: [AC, AC, AC]