diff --git a/src/lib.rs b/src/lib.rs
index fb13107..01ea6cd 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -25,12 +25,6 @@ pub enum Urgency {
     High,
 }
 
-#[test]
-fn urgency_ord_does_the_right_thing() {
-    assert!(Urgency::High > Urgency::Normal);
-    assert!(Urgency::Normal > Urgency::Low);
-}
-
 /// The entire to-do list.
 #[derive(Debug, Default)]
 pub struct TodoList {
@@ -44,6 +38,10 @@ impl TodoList {
         TodoList::default()
     }
 
+    pub fn add_full_item(&mut self, item: &Item) {
+        self.items.push(item.clone());
+    }
+
     /// Adds a new item with default settings to the to-do list.
     pub fn add(&mut self, item_text: String) {
         todo!("Insert code here to add an item to the todo list")
@@ -75,7 +73,17 @@ impl TodoList {
         urgency_at_least: Option<Urgency>,
         urgency_at_most: Option<Urgency>,
     ) -> Vec<(usize, Item)> {
-        todo!("Insert code here to search for items based on given criteria.")
+        self.items.iter().enumerate().filter(|(_, item)| {
+            (urgency_at_least.is_some() && // Some > None, add this check
+             Some(&item.urgency) >= urgency_at_least.as_ref()) ||
+            // no need to worry about is_some check as Some > None
+            Some(&item.urgency) <= urgency_at_most.as_ref() ||
+            Some(&item.text) == text_substr.as_ref() ||
+            Some(&item.checked) == checked.as_ref() ||
+            item.due_at.map_or(false, 
+                |date| Some(date - Utc::now()) <= due_in_less_than
+            ) 
+        }).map(|(ind, item)| (ind, (*item).clone())).collect()
     }
 
     /// Sets whether a to-do item is checked off.
@@ -98,3 +106,247 @@ impl TodoList {
         todo!("Insert code here to set the urgency of an item.")
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /* urgency tests */
+    #[test]
+    fn urgency_ord_does_the_right_thing() {
+        assert!(Urgency::High > Urgency::Normal);
+        assert!(Urgency::Normal > Urgency::Low);
+    }
+
+    /* search tests */
+    fn setup_search_tests(add: bool) -> (Vec<Item>, TodoList) {
+        let mut list = TodoList::new();
+        let mut item_vec: Vec<Item> = vec![];
+        if add {
+            let item1 = Item { 
+                text: String::from("I am item1!"),
+                checked: false,
+                due_at: None,
+                urgency: Urgency::Low   
+            };
+    
+            let item2 = Item {
+                text: String::from("I am item2!"),
+                checked: true,
+                due_at: Some(Utc::now() + Duration::seconds(100000)), // 27 hours roughly
+                urgency: Urgency::High
+            };
+    
+            let item3 = Item {
+                text: String::from("I am item3!"),
+                checked: false,
+                due_at: None,
+                urgency: Urgency::Normal
+            };
+
+            item_vec.extend([item1, item2, item3]);
+            for item in item_vec.iter() {
+                list.add_full_item(&item);
+            }
+        };
+
+        (item_vec, list)
+    }
+
+    fn compare_items(item1: &Item, item2: &Item) {
+        assert!(item1.text == item2.text);
+        assert!(item1.urgency == item2.urgency);
+        assert!(item1.checked == item2.checked);
+        assert!(item1.due_at == item2.due_at);
+    }
+
+    fn compare_item_lists(list1: &Vec<(usize, Item)>, list2: &Vec<Item>) {
+        assert!(list1.len() == list2.len());
+        for (ind, item) in list1.iter() {
+            assert!(ind < &list2.len());
+            let act_item = &list2[*ind];
+            compare_items(item, act_item);
+        }
+    }
+
+    #[test]
+    fn none_search_on_empty_list_returns_nothing() {
+        let (_, list) = setup_search_tests(false);
+
+        let empty_list = list.search(None, None, None, None, None);
+
+        assert!(empty_list.len() == 0);
+    }
+
+    #[test]
+    fn non_none_search_on_empty_list_returns_nothing() {
+        let (_, list) = setup_search_tests(false);
+
+        let empty_list = list.search(
+            Some(String::from("nothing here!")), 
+            None, None, None, None
+        );
+
+        assert!(empty_list.len() == 0);
+    }
+
+    #[test]
+    fn none_search_on_full_list_returns_nothing() {
+        let (_, list) = setup_search_tests(true);
+
+        let empty_list = list.search(None, None, None, None, None);
+
+        assert!(empty_list.len() == 0);
+    }
+
+    #[test]
+    fn search_on_full_list_with_no_matchable_items_returns_nothing() {
+        let (_, list) = setup_search_tests(true);
+
+        let empty_list = list.search(
+            Some(String::from("nothing here!")),
+            None, None, None, None
+        );
+
+        assert!(empty_list.len() == 0);
+    }
+
+    #[test]
+    fn search_on_list_with_one_matching_item() {
+        let (items, list) = setup_search_tests(true);
+
+        let one_list = list.search(
+            Some(String::from("I am item1!")), 
+            None, None, None, None
+        );
+
+        assert!(one_list.len() == 1);
+        
+        let (ind, item) = &one_list[0];
+        let (act_ind, act_item) = (0, &items[0]);
+        assert!(*ind == act_ind);
+        compare_items(&item, act_item);
+    }
+
+    #[test]
+    fn search_on_list_matching_all() {
+        let (items, list) = setup_search_tests(true);
+
+        let all_list = list.search(
+            None, None, None, Some(Urgency::Low), Some(Urgency::High)
+        );
+
+        compare_item_lists(&all_list, &items);
+    }
+
+    #[test]
+    fn search_returned_values_arent_modified() {
+        let (_, list) = setup_search_tests(true);
+
+        let all_list = list.search(
+            None, None, None, Some(Urgency::Low), Some(Urgency::High)
+        );
+
+        compare_item_lists(&all_list, &list.items);
+    }
+
+    #[test]
+    fn search_on_string() {
+        let (items, list) = setup_search_tests(true);
+
+        let string_list = list.search(
+            Some(String::from("I am item2!")), None, None, None, None
+        );
+
+        assert!(string_list.len() == 1);
+        let (ind, item) = &string_list[0];
+        assert!(*ind < items.len());
+        assert!(*ind == 1);
+        compare_items(&item, &items[*ind]);
+    }
+
+    #[test]
+    fn search_on_checked() {
+        let (items, list) = setup_search_tests(true);
+
+        let checked_list = list.search(
+            None, Some(true), None, None, None
+        );
+
+        assert!(checked_list.len() == 1);
+        let (ind, item) = &checked_list[0];
+        assert!(*ind < items.len());
+        assert!(*ind == 1);
+        compare_items(&item, &items[*ind]);
+    }
+
+    #[test]
+    fn search_on_due_before() {
+        let (items, list) = setup_search_tests(true);
+
+        let due_list = list.search(
+            None, None, Some(Duration::seconds(200000)), None, None
+        );
+        assert!(due_list.len() == 1);
+        let (ind, item) = &due_list[0];
+        assert!(*ind < items.len());
+        assert!(*ind == 1);
+        compare_items(&item, &items[*ind]);
+    }
+
+    #[test]
+    fn search_on_least_urgency() {
+        let (items, list) = setup_search_tests(true);
+
+        let least_list = list.search(
+            None, None, None, Some(Urgency::Normal), None
+        );
+
+        assert!(least_list.len() == 2);
+        let (ind1, item1) = &least_list[0];
+        let (ind2, item2) = &least_list[1];
+        assert!(*ind1 < items.len() && *ind2 < items.len());
+        assert!(*ind1 == 1 && *ind2 == 2);
+        compare_items(&item1, &items[*ind1]);
+        compare_items(&item2, &items[*ind2]);
+    }
+
+    #[test]
+    fn search_on_most_urgency() {
+        let (items, list) = setup_search_tests(true);
+
+        let most_list = list.search(
+            None, None, None, None, Some(Urgency::Normal)
+        );
+
+        assert!(most_list.len() == 2);
+        let (ind1, item1) = &most_list[0];
+        let (ind2, item2) = &most_list[1];
+        assert!(*ind1 < items.len() && *ind2 < items.len());
+        assert!(*ind1 == 0 && *ind2 == 2);
+        compare_items(&item1, &items[*ind1]);
+        compare_items(&item2, &items[*ind2]);
+    }
+
+    // doesn't actually test anything, just times the search function
+    // should be run with the --nocapture argument to actually show stdout
+    #[test]
+    fn timing_test() {
+        let (_, mut list) = setup_search_tests(false);
+        for i in 1..1_000_000 {
+            list.add_full_item(&Item {
+                text: format!("I am item {i}!"),
+                checked: true,
+                due_at: None,
+                urgency: Urgency::Normal
+            })
+        }
+
+        let before = Utc::now();
+        list.search(None, Some(true), None, None, None);
+        let after = Utc::now();
+
+        let diff = (after - before).num_milliseconds();
+        println!("Duration: {diff}");
+    }
+}