Return error message from SQLite

tests/lib.rs

@@ -55,6 +55,17 @@ fn workflow() {
     }
 }
 
+#[test]
+fn failure() {
+    let (path, _directory) = setup();
+    let mut database = ok!(sqlite::open(&path));
+    match database.execute(":)", None) {
+        Err(error) => assert_eq!(error.message,
+                                 Some(String::from("SQL logic error or missing database"))),
+        _ => assert!(false),
+    }
+}
+
 fn setup() -> (PathBuf, Directory) {
     let directory = ok!(Directory::new("sqlite"));
     (directory.path().join("database.sqlite3"), directory)