Initial commit

exercises/17_tests/README.md

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+# Tests
+
+Going out of order from the book to cover tests -- many of the following exercises will ask you to make tests pass!
+
+## Further information
+
+- [Writing Tests](https://doc.rust-lang.org/book/ch11-01-writing-tests.html)

exercises/17_tests/tests1.rs

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+// Tests are important to ensure that your code does what you think it should
+// do.
+
+fn is_even(n: i64) -> bool {
+    n % 2 == 0
+}
+
+fn main() {
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    // TODO: Import `is_even`. You can use a wildcard to import everything in
+    // the outer module.
+
+    use super::is_even;
+
+    #[test]
+    fn you_can_assert() {
+        // TODO: Test the function `is_even` with some values.
+        assert!(is_even(2));
+        assert!(is_even(4));
+    }
+}

exercises/17_tests/tests2.rs

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+// Calculates the power of 2 using a bit shift.
+// `1 << n` is equivalent to "2 to the power of n".
+fn power_of_2(n: u8) -> u64 {
+    1 << n
+}
+
+fn main() {
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn you_can_assert_eq() {
+        // TODO: Test the function `power_of_2` with some values.
+        assert_eq!(power_of_2(1), 2);
+        assert_eq!(power_of_2(2), 4);
+        assert_eq!(power_of_2(3), 8);
+        assert_eq!(power_of_2(4), 16);
+    }
+}

exercises/17_tests/tests3.rs

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+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 must be positive");
+        }
+
+        Rectangle { width, height }
+    }
+}
+
+fn main() {
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn correct_width_and_height() {
+        // TODO: This test should check if the rectangle has the size that we
+        // pass to its constructor.
+        let rect = Rectangle::new(10, 20);
+        assert_eq!(rect.width, 10); // Check width
+        assert_eq!(rect.height, 20); // Check height
+    }
+
+    // TODO: This test should check if the program panics when we try to create
+    // a rectangle with negative width.
+    #[test]
+    #[should_panic(expected = "Rectangle width and height must be positive")]
+    fn negative_width() {
+        let _rect = Rectangle::new(-10, 10);
+    }
+
+    // TODO: This test should check if the program panics when we try to create
+    // a rectangle with negative height.
+    #[test]
+    #[should_panic(expected = "Rectangle width and height must be positive")]
+    fn negative_height() {
+        let _rect = Rectangle::new(10, -10);
+    }
+}