Remove tests3 and add solution to tests4

solutions/17_tests/tests3.rs

@@ -1 +1,45 @@
-// Solutions will be available before the stable release. Thank you for testing the beta version 🥰
+struct Rectangle {
+    width: i32,
+    height: i32,
+}
+
+impl Rectangle {
+    // Don't change this function.
+    fn new(width: i32, height: i32) -> Self {
+        if width <= 0 || height <= 0 {
+            // Returning a `Result` would be better here. But we want to learn
+            // how to test functions that can panic.
+            panic!("Rectangle width and height can't be negative");
+        }
+
+        Rectangle { width, height }
+    }
+}
+
+fn main() {
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn correct_width_and_height() {
+        let rect = Rectangle::new(10, 20);
+        assert_eq!(rect.width, 10); // Check width
+        assert_eq!(rect.height, 20); // Check height
+    }
+
+    #[test]
+    #[should_panic] // Added this attribute to check that the test panics.
+    fn negative_width() {
+        let _rect = Rectangle::new(-10, 10);
+    }
+
+    #[test]
+    #[should_panic] // Added this attribute to check that the test panics.
+    fn negative_height() {
+        let _rect = Rectangle::new(10, -10);
+    }
+}

solutions/17_tests/tests4.rs

@@ -1 +0,0 @@
-// Solutions will be available before the stable release. Thank you for testing the beta version 🥰