feat: basic one to one relation

src/tests/relation_test.rs

@@ -0,0 +1,52 @@
+#[cfg(test)]
+mod relation_test {
+    use std::borrow::BorrowMut;
+
+    use crate::database::{
+        relation::{OneToOne, Relation},
+        table::Table,
+        Database,
+    };
+
+    #[test]
+    fn should_fail_no_relation_found() {
+        let cat_relations =
+            hashmap!["cat_food" => Relation::new("Food".to_string(), "one_to_one".to_string())];
+        let cat_table: Table = Table::new("Cats", "id", None, Some(cat_relations));
+
+        let food_table: Table = Table::new("Food", "id", None, None);
+
+        let mut database: Database = Database::new(vec![cat_table, food_table]);
+
+        _ = database
+            .get_table("Food".to_string())
+            .unwrap()
+            .insert_row(row!["id" => 123, "name" => "Dry Feed"]);
+        let _ = database.get_table("Cats".to_string()).unwrap().insert_row(row!["id" => 1, "name" => "Ozzy", "breed" => "mixed", "food" => OneToOne::new(123u64, "cat_food".to_string())]);
+
+        let cat_table = database.get_table("Cats".to_string()).unwrap();
+        let cat_1 = cat_table.find_by_pk(1u64).unwrap();
+
+        let cat_1_food = cat_1.get("food").unwrap();
+
+        let relation = OneToOne::from_value(cat_1_food.to_owned());
+        assert_eq!(relation.get_id(), 123u64);
+
+        let foreign_row = relation.get("Cats".to_string(), database.borrow_mut());
+
+        assert_eq!(foreign_row.is_ok(), true);
+
+        let foreign_row_unwrapped = foreign_row.unwrap();
+
+        assert_eq!(
+            foreign_row_unwrapped.get("id").unwrap().as_u64().unwrap(),
+            123u64
+        );
+    }
+    #[test]
+    fn should_fail_no_table_found() {}
+    #[test]
+    fn should_fail_no_row_found() {}
+    // Fail without table found, invalid relation
+    // Fail row and table found but not row
+}