moved iterator exercises

exercises/iterators/iterators3.rs

@@ -0,0 +1,85 @@
+// iterators3.rs
+// This is a bigger exercise than most of the others! You can do it!
+// Here is your mission, should you choose to accept it:
+// 1. Complete the divide function to get the first four tests to pass.
+// 2. Get the remaining tests to pass by completing the result_with_list and
+//    list_of_results functions.
+// Execute `rustlings hint iterators3` or use the `hint` watch subcommand for a hint.
+
+// I AM NOT DONE
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum DivisionError {
+    NotDivisible(NotDivisibleError),
+    DivideByZero,
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct NotDivisibleError {
+    dividend: i32,
+    divisor: i32,
+}
+
+// Calculate `a` divided by `b` if `a` is evenly divisible by `b`.
+// Otherwise, return a suitable error.
+pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {
+    todo!();
+}
+
+// Complete the function and return a value of the correct type so the test passes.
+// Desired output: Ok([1, 11, 1426, 3])
+fn result_with_list() -> () {
+    let numbers = vec![27, 297, 38502, 81];
+    let division_results = numbers.into_iter().map(|n| divide(n, 27));
+}
+
+// Complete the function and return a value of the correct type so the test passes.
+// Desired output: [Ok(1), Ok(11), Ok(1426), Ok(3)]
+fn list_of_results() -> () {
+    let numbers = vec![27, 297, 38502, 81];
+    let division_results = numbers.into_iter().map(|n| divide(n, 27));
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_success() {
+        assert_eq!(divide(81, 9), Ok(9));
+    }
+
+    #[test]
+    fn test_not_divisible() {
+        assert_eq!(
+            divide(81, 6),
+            Err(DivisionError::NotDivisible(NotDivisibleError {
+                dividend: 81,
+                divisor: 6
+            }))
+        );
+    }
+
+    #[test]
+    fn test_divide_by_0() {
+        assert_eq!(divide(81, 0), Err(DivisionError::DivideByZero));
+    }
+
+    #[test]
+    fn test_divide_0_by_something() {
+        assert_eq!(divide(0, 81), Ok(0));
+    }
+
+    #[test]
+    fn test_result_with_list() {
+        assert_eq!(format!("{:?}", result_with_list()), "Ok([1, 11, 1426, 3])");
+    }
+
+    #[test]
+    fn test_list_of_results() {
+        assert_eq!(
+            format!("{:?}", list_of_results()),
+            "[Ok(1), Ok(11), Ok(1426), Ok(3)]"
+        );
+    }
+}