initial commit

exercises/02_basic_calculator/02_variables/src/lib.rs

@@ -0,0 +1,34 @@
+// 👇 The lines below, starting with `///`, are called **documentation comments**.
+//    They attach documentation to the item that follows them. In this case, the `speed` function.
+//    If you run `cargo doc --open` from this exercise's directory, Rust will generate
+//    HTML documentation from these comments and open it in your browser.
+
+/// Given the start and end points of a journey, and the time it took to complete it,
+/// calculate the average speed.
+pub fn speed(start: u32, end: u32, time_elapsed: u32) -> u32 {
+    // TODO: define a variable named `distance` with the right value to get tests to pass
+    //  Do you need to annotate the type of `distance`? Why or why not?
+
+    // Don't change the line below
+    distance / time_elapsed
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::speed;
+
+    #[test]
+    fn case1() {
+        assert_eq!(speed(0, 10, 10), 1);
+    }
+
+    #[test]
+    fn case2() {
+        assert_eq!(speed(10, 30, 10), 2);
+    }
+
+    #[test]
+    fn case3() {
+        assert_eq!(speed(10, 31, 10), 2);
+    }
+}