1 files changed, 73 insertions, 0 deletions
diff --git a/solutions/18_iterators/iterators3.rs b/solutions/18_iterators/iterators3.rs
new file mode 100644
index 0000000..d66d1ef
--- /dev/null
+++ b/solutions/18_iterators/iterators3.rs
@@ -0,0 +1,73 @@
+#[derive(Debug, PartialEq, Eq)]
+enum DivisionError {
+    DivideByZero,
+    NotDivisible,
+}
+
+fn divide(a: i64, b: i64) -> Result<i64, DivisionError> {
+    if b == 0 {
+        return Err(DivisionError::DivideByZero);
+    }
+
+    if a % b != 0 {
+        return Err(DivisionError::NotDivisible);
+    }
+
+    Ok(a / b)
+}
+
+fn result_with_list() -> Result<Vec<i64>, DivisionError> {
+    //                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+    let numbers = [27, 297, 38502, 81];
+    let division_results = numbers.into_iter().map(|n| divide(n, 27));
+    // Collects to the expected return type. Returns the first error in the
+    // division results (if one exists).
+    division_results.collect()
+}
+
+fn list_of_results() -> Vec<Result<i64, DivisionError>> {
+    //               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+    let numbers = [27, 297, 38502, 81];
+    let division_results = numbers.into_iter().map(|n| divide(n, 27));
+    // Collects to the expected return type.
+    division_results.collect()
+}
+
+fn main() {
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_success() {
+        assert_eq!(divide(81, 9), Ok(9));
+    }
+
+    #[test]
+    fn test_divide_by_0() {
+        assert_eq!(divide(81, 0), Err(DivisionError::DivideByZero));
+    }
+
+    #[test]
+    fn test_not_divisible() {
+        assert_eq!(divide(81, 6), Err(DivisionError::NotDivisible));
+    }
+
+    #[test]
+    fn test_divide_0_by_something() {
+        assert_eq!(divide(0, 81), Ok(0));
+    }
+
+    #[test]
+    fn test_result_with_list() {
+        assert_eq!(result_with_list().unwrap(), [1, 11, 1426, 3]);
+    }
+
+    #[test]
+    fn test_list_of_results() {
+        assert_eq!(list_of_results(), [Ok(1), Ok(11), Ok(1426), Ok(3)]);
+    }
+}