Added general environment function (#20)

Reviewed-on: #20
Co-authored-by: phoenix <kundeng00@pm.me>
Co-committed-by: phoenix <kundeng00@pm.me>

tests/test.rs

@@ -59,4 +59,23 @@ mod tests {
             result
         )
     }
+
+    #[test]
+    fn test_get_env() {
+        let keys = vec![
+            (
+                "RANDOM_ENV_KEY",
+                "YouDon'tWantToButYouGottaChange|It'sGoingToHurtYouTryingToStayTheSame|AreYouInItOrYouInItForTheFame?|I'mTryingToFigureOutWhoLoveMeForMe",
+            ),
+            (
+                "MODNAR_ENV_KEY",
+                "FeelingTheMonsterClimbDeepserInsideOfMe|FeelingHimGnawingMyHeartAwayHungrily|I'llNeverLoseThisPain|NeverDreamOfYouAgain",
+            ),
+        ];
+
+        for (key, value) in keys.iter() {
+            let result = async_std::task::block_on(icarus_envy::environment::get_env(key));
+            assert_eq!(result, *value, "{:?} does not match {:?}", key, result)
+        }
+    }
 }