add rudimentary tests for solvability of generated sudokus

src/sudoku/generator.rs

@@ -91,7 +91,7 @@ pub fn generate_sudoku(difficulty: Difficulty) -> Board {
 /// TODO: currently empty cells needs to be recreated
 ///       on each recursive call, and are randomized anew
 ///       each time, which is an unnecessary overhead.
-fn solve_random(board: &mut Board) -> Result<(), ()> {
+pub fn solve_random(board: &mut Board) -> Result<(), ()> {
     let mut empty_cells: Vec<(usize, usize)> = Vec::new();
 
     let mut rows: Vec<usize> = (0..9).collect::<Vec<_>>();

src/tests/generator.rs

@@ -1,4 +1,4 @@
-use crate::{generate_sudoku, Board, Difficulty};
+use crate::{generator::*, Board};
 
 #[test]
 fn generated_sudoku_uniqueness() {
@@ -30,3 +30,33 @@ fn generated_sudoku_uniqueness() {
         iterations - uniques.len()
     );
 }
+
+
+#[test]
+fn generated_sudoku_solvability_small() {
+    use Difficulty::*;
+
+    let iterations = 20;
+
+    for difficulty in [Easy, Mid, Hard, Expert] {
+        for _ in 0..iterations {
+            let mut sudoku = generate_sudoku(difficulty);
+            solve_random(&mut sudoku).expect("Generated sudoku not solvable");
+        }
+    }
+}
+
+#[test]
+#[ignore]
+fn generated_sudoku_solvability_large() {
+    use Difficulty::*;
+
+    let iterations = 400;
+
+    for difficulty in [Easy, Mid, Hard, Expert] {
+        for _ in 0..iterations {
+            let mut sudoku = generate_sudoku(difficulty);
+            solve_random(&mut sudoku).expect("Generated sudoku not solvable");
+        }
+    }
+}