score+test, Tests for a42853a & test_utils mod

Tests for all the core functionality implemented to score in a42853a.

Optimistically adding a test_utils mod for shared test code

koucha/src/test_utils.rs

@@ -0,0 +1,11 @@
+#![cfg(test)]
+
+use chrono::{
+  Utc,
+  TimeZone,
+  DateTime
+};
+
+pub fn get_datetime() -> DateTime<Utc> {
+  Utc.with_ymd_and_hms(2020,1,1,0,0,0).unwrap()
+}