feat: Add traits3.rs exercise

exercises/traits/traits3.rs

@@ -0,0 +1,40 @@
+// traits3.rs
+//
+// Your task is to implement the Licensed trait for
+// both structures and have them return the same
+// information without writing the same function twice.
+//
+// Consider what you can add to the Licensed trait.
+
+// I AM NOT DONE
+
+pub trait Licensed {
+    fn licensing_info(&self) -> String;
+}
+
+struct SomeSoftware {
+    version_number: i32,
+}
+
+struct OtherSoftware {
+    version_number: String,
+}
+
+impl Licensed for SomeSoftware {} // Don't edit this line
+impl Licensed for OtherSoftware {} // Don't edit this line
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn is_licensing_info_the_same() {
+        let licensing_info = String::from("Some information");
+        let some_software = SomeSoftware { version_number: 1 };
+        let other_software = OtherSoftware {
+            version_number: "v2.0.0".to_string(),
+        };
+        assert_eq!(some_software.licensing_info(), licensing_info);
+        assert_eq!(other_software.licensing_info(), licensing_info);
+    }
+}

info.toml

@@ -704,6 +704,18 @@ what the result should look like!
 Vectors provide suitable methods for adding an element at the end. See
 the documentation at: https://doc.rust-lang.org/std/vec/struct.Vec.html"""
 
+[[exercises]]
+name = "traits3"
+path = "exercises/traits/traits3.rs"
+mode = "test"
+hint = """
+Traits can have a default implementation for functions. Structs that implement
+the trait can then use the default version of these functions if they choose not
+implement the function themselves.
+
+See the documentation at: https://doc.rust-lang.org/book/ch10-02-traits.html#default-implementations
+"""
+
 # QUIZ 3
 
 [[exercises]]