Test: First simple solving test

src/sudoku_solver.rs

@@ -0,0 +1,41 @@
+use crate::playfield::Playfield;
+
+pub struct SudokuSolver {
+    playfield: Playfield,
+}
+
+impl SudokuSolver {
+    pub fn new(playfield: &Playfield) -> SudokuSolver {
+        Self {
+            playfield: playfield.clone(),
+        }
+    }
+    pub fn solve(&self) -> Playfield {
+        return self.playfield.clone();
+    }
+
+    fn populate_possible_values(&self) {
+        for row in &self.playfield.fields {
+            for field in row {
+                if field.value.is_some() {
+                    continue;
+                }
+            }
+        }
+    }
+}
+#[cfg(test)]
+mod tests {
+    mod solve {
+        use super::super::*;
+        #[test]
+        fn simple() {
+            let playfield = Playfield::new(&"1 2 3 2 3 1 3 1 0".to_string(), 3);
+            let expected = Playfield::new(&"1 2 3 2 3 1 3 1 2".to_string(), 3);
+
+            let solved = SudokuSolver::new(&playfield).solve();
+
+            assert_eq!(solved, expected);
+        }
+    }
+}