[Josh] Week 3 solution

week3/Cargo.toml

@@ -6,3 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+rand = "0.8.5"

week3/src/lib.rs

@@ -1 +1,85 @@
+use rand::prelude::*;
+use std::f64::consts::PI;
 
+#[derive(Debug)]
+pub enum Shape {
+    Circle(f64),
+    Square(isize),
+    Rectangle(isize, isize),
+}
+
+pub fn area(shape: &Shape) -> f64 {
+    match shape {
+        Shape::Circle(radius) => radius * radius * PI,
+        Shape::Square(length) => (length * length) as f64,
+        Shape::Rectangle(width, height) => (height * width) as f64,
+    }
+}
+
+pub fn random_shape() -> Shape {
+    let mut rng = rand::thread_rng();
+    let random_number: isize = rng.gen_range(0..2);
+
+    match random_number {
+        0 => Shape::Circle(rng.gen()),
+        1 => Shape::Rectangle(rng.gen(), rng.gen()),
+        _ => Shape::Square(rng.gen()),
+    }
+}
+
+pub fn circle_area(shape: &Shape) -> Option<f64> {
+    if let Shape::Circle(shape) = shape {
+        Some(area(&Shape::Circle(*shape)))
+    } else {
+        None
+    }
+}
+
+#[cfg(test)]
+mod test_shape_areas {
+    use super::*;
+
+    #[test]
+    fn gets_area_of_circle() {
+        const RADIUS: f64 = 1.0;
+        const ANSWER: f64 = 3.141592653589793;
+
+        let circle = Shape::Circle(RADIUS);
+
+        assert_eq!(ANSWER, area(&circle));
+    }
+    #[test]
+    fn gets_area_of_rectangle() {
+        const WIDTH: isize = 100;
+        const HEIGHT: isize = 20;
+        const ANSWER: f64 = 2000.0 as f64;
+        let rectangle = Shape::Rectangle(WIDTH, HEIGHT);
+
+        assert_eq!(ANSWER, area(&rectangle));
+    }
+    #[test]
+    fn gets_area_of_square() {
+        const LENGTH: isize = 100;
+        const ANSWER: f64 = 10000.0 as f64;
+        let square = Shape::Square(LENGTH);
+
+        assert_eq!(ANSWER, area(&square));
+    }
+    #[test]
+    fn gets_circle_area() {
+        const RADIUS: f64 = 1.0;
+        const ANSWER: Option<f64> = Some(3.141592653589793);
+
+        let circle = Shape::Circle(RADIUS);
+
+        assert_eq!(ANSWER, circle_area(&circle));
+    }
+    #[test]
+    fn gets_circle_area_else() {
+        const LENGTH: isize = 100;
+
+        let square = Shape::Square(LENGTH);
+
+        assert_eq!(None, circle_area(&square));
+    }
+}

week3/src/main.rs

@@ -0,0 +1,6 @@
+use week3::random_shape;
+
+fn main() {
+    let shape = random_shape();
+    println!("{:?}", shape);
+}