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/lib.rs

@@ -3,6 +3,10 @@ use std::error::Error;
 type Result<T> = std::result::Result<T, Box<dyn Error>>;
 
 pub mod score;
+
+#[cfg(test)]
+pub mod test_utils;
+
 pub struct AdapterPool(sqlx::SqlitePool);
 pub struct AdapterBuilder {
   database_url: String,