Account for days elapsed based on latest datev0.1.2

Instead of counting the number of days for the averge through
the number of iterations, let it be the difference between the latest
date on entry and the start of the period. Id est:

* 'Missing' dates from the input are implicit.
* The order of the days doesn't affect the output (although it doesn't
make sense to put the days out of order).

2 files changed, 18 insertions, 17 deletions

diff --git a/budget/tests/budget.rs b/budget/tests/budget.rs
index 1cc02e7..feae240 100644
--- a/budget/tests/budget.rs
+++ b/budget/tests/budget.rs
@@ -1,6 +1,6 @@
 use std::collections::HashMap;
 
-use chrono::prelude::*;
+use chrono::NaiveDate;
 
 use budget::*;
 
@@ -62,6 +62,10 @@ fn can_parse_account() -> Result<(), ParseError>{
                 ],
             },
             Day {
+                date: NaiveDate::from_ymd(2020, 10, 4),
+                expenses: Vec::<Expense>::new(),
+            },
+            Day {
                 date: NaiveDate::from_ymd(2020, 10, 2),
                 expenses: vec![
                     Expense {
@@ -82,10 +86,6 @@ fn can_parse_account() -> Result<(), ParseError>{
                     },
                 ],
             },
-            Day {
-                date: NaiveDate::from_ymd(2020, 10, 3),
-                expenses: Vec::<Expense>::new(),
-            },
         ],
     };
 
@@ -99,32 +99,33 @@ fn can_parse_account() -> Result<(), ParseError>{
 #[test]
 fn can_calculate() -> Result<(), ParseError> {
     let mut should_be = Calculated {
-        all_day_average: 7.57,
-        essential_day_average: 6.3,
+        all_day_average: 5.6775,
+        essential_day_average: 4.725,
         categories_day_average: HashMap::<String, f64>::new(),
         essential_subtotal: 18.9,
         categories_subtotal: HashMap::<String, f64>::new(),
         total: 22.71,
         balance: 397.29,
-        days_left: 52.48216644649934,
-        days_left_essential: 63.06190476190476,
+        days_left: 69.9762219286658,
+        days_left_essential: 84.08253968253969,
+        last_day: NaiveDate::from_ymd(2020, 10, 04),
     };
 
     should_be.categories_day_average.insert(
         "supplies".to_string(),
-        1.27,
+        0.9525,
     );
     should_be.categories_day_average.insert(
         "products".to_string(),
-        2.3333333333333335,
+        1.75,
     );
     should_be.categories_day_average.insert(
         "transport".to_string(),
-        2.3000000000000003,
+        1.725,
     );
     should_be.categories_day_average.insert(
         "utilities".to_string(),
-        1.6666666666666667,
+        1.25,
     );
 
     should_be.categories_subtotal.insert(
@@ -145,7 +146,7 @@ fn can_calculate() -> Result<(), ParseError> {
     );
 
     let account = budget::parse_account("tests/test.toml")?;
-    let actually_is = budget::calculate(&account);
+    let actually_is = budget::calculate(&account).unwrap();
 
     assert_eq!(actually_is, should_be);
 
diff --git a/budget/tests/test.toml b/budget/tests/test.toml
index 1bb1ce7..a29467e 100644
--- a/budget/tests/test.toml
+++ b/budget/tests/test.toml
@@ -39,6 +39,9 @@ date = 2020-10-01
   shared = 2
 
 [[days]]
+date = 2020-10-04
+
+[[days]]
 date = 2020-10-02
 
   [[days.expenses]]
@@ -52,6 +55,3 @@ date = 2020-10-02
   price = 6.9
   category = "transport"
 
-[[days]]
-date = 2020-10-03
-