Implement Gigasecond exercise

config.json

@@ -11,6 +11,7 @@
     "allergies",
     "word-count",
     "hamming",
+    "gigasecond",
     "rna-transcription",
     "nucleotide-count",
     "nucleotide-codons",

exercises/gigasecond/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "gigasecond"
+version = "0.0.0"
+
+[dependencies]
+chrono = "0.2"
+

exercises/gigasecond/example.rs

@@ -0,0 +1,6 @@
+extern crate chrono;
+use chrono::*;
+
+pub fn after(start: DateTime<UTC>) -> DateTime<UTC> {
+    start + Duration::seconds(1_000_000_000)
+}

exercises/gigasecond/tests/gigasecond.rs

@@ -0,0 +1,50 @@
+extern crate gigasecond;
+
+/*
+ * Students,
+ *
+ * Rust does not currently have a library for handling Time. To solve this exercise
+ * you'll need to use the Chrono 'crate' (which is Rust's term for an external library).
+ *
+ * The first time you run `cargo test`, the Chrono crate will automatically be downloaded
+ * and installed. More information on crates can be found at
+ * https://doc.rust-lang.org/book/guessing-game.html#generating-a-secret-number
+ *
+ * In order to use the crate, your solution will need to start with the two following lines
+*/
+extern crate chrono;
+use chrono::*;
+
+#[test]
+fn test_date() {
+    let start_date = UTC.ymd(2011, 4, 25).and_hms(0,0,0);
+    assert_eq!(gigasecond::after(start_date), UTC.ymd(2043, 1, 1).and_hms(1,46,40));
+}
+
+#[test]
+#[ignore]
+fn test_another_date() {
+    let start_date = UTC.ymd(1977, 6, 13).and_hms(0,0,0);
+    assert_eq!(gigasecond::after(start_date), UTC.ymd(2009, 2, 19).and_hms(1,46,40));
+}
+
+#[test]
+#[ignore]
+fn test_third_date() {
+    let start_date = UTC.ymd(1959, 7, 19).and_hms(0,0,0);
+    assert_eq!(gigasecond::after(start_date), UTC.ymd(1991, 3, 27).and_hms(1,46,40));
+}
+
+#[test]
+#[ignore]
+fn test_datetime() {
+    let start_date = UTC.ymd(2015, 1, 24).and_hms(22,0,0);
+    assert_eq!(gigasecond::after(start_date), UTC.ymd(2046, 10, 2).and_hms(23,46,40));
+}
+
+#[test]
+#[ignore]
+fn test_another_datetime() {
+    let start_date = UTC.ymd(2015, 1, 24).and_hms(23,59,59);
+    assert_eq!(gigasecond::after(start_date), UTC.ymd(2046, 10, 3).and_hms(1,46,39));
+}