Correct 24h timefix/correct_24h_time

While respecting that there is one culture which has colonized this planet, as
well as managed to make its language the lingua franca of the contemporary
world, its typical use of 12h time can not excuse going as wild with "parsing
English time expressions" as this crate does prior to this commit.

One might consult https://en.wikipedia.org/wiki/24-hour_clock to learn about
reasonable expectations.

Specifically, this fixes the bugs:

 * No times during the interval 00:00-00:59 were allowed.
 * The time 24:00 was considered 00:00, of the wrong (preceeding) day.
 * Bogus times in the interval 24:00-24:59 were allowed.

After this commit 24:00 becomes an invalid time. Correctly rewriting it to
00:00, with overflow to the next day, is left as an excercise to whoever feels
strongly enough for that edge functionality.

1 files changed, 30 insertions, 8 deletions

diff --git a/tests/tests.rs b/tests/tests.rs
index a2852d8..1c593be 100644
--- a/tests/tests.rs
+++ b/tests/tests.rs
@@ -1587,18 +1587,40 @@ fn simple_noon_past_and_future() {
 fn midnight() {
     let d1 = NaiveDate::from_ymd(1969, 5, 7).and_hms(0, 0, 0);
     let d2 = d1 + Duration::seconds(1);
-    match parse("midnight on May 6, 1969", None) {
-        Ok((start, end, _)) => {
-            assert_eq!(d1, start);
-            assert_eq!(d2, end);
-        }
-        Err(e) => {
-            println!("{:?}", e);
-            assert!(false, "didn't match");
+    for phrase in [
+        "midnight on May 6, 1969",
+        // TODO Add 12h representation, whichever is considered midnight?!
+        //      Possible am/pm might differ between GB and some colonial time
+        //      representations, just as an imperial gallon is roughly 4.5
+        //      litres while a US gallon is not even 3.8 liters.
+        "00:00 on May 7, 1969", ].iter()
+    {
+        match parse(phrase, None) {
+            Ok((start, end, _)) => {
+                assert_eq!(d1, start);
+                assert_eq!(d2, end);
+            }
+            Err(e) => {
+                println!("{:?}", e);
+                assert!(false, "didn't match");
+            }
         }
     }
 }
 
+#[test]
+fn invalid_24_00() {
+    // While 24:00 might arguably be an ok time, is not implemented in this crate.
+    let phrase = "24:00";
+    assert!(parse(phrase, None).is_err());
+}
+
+#[test]
+fn super_invalid_24_30() {
+    let phrase = "24:30";
+    assert!(parse(phrase, None).is_err());
+}
+
 #[derive(Debug)]
 enum Period {
     Week,