Add test cases for panicking general_section

src/lib.rs

@@ -1344,6 +1344,18 @@ mod test {
         assert!(!props.contains_key("k1"));
     }
 
+    #[test]
+    fn load_from_str_with_empty_input() {
+        let input = "\n\n\n";
+        let opt = Ini::load_from_str(input);
+        assert!(opt.is_ok());
+
+        let mut output = opt.unwrap();
+        assert!(output.general_section().is_empty());
+        assert!(output.general_section_mut().is_empty());
+        assert_eq!(output.len(), 1);
+    }
+
     #[test]
     #[cfg(not(feature = "brackets-in-section-names"))]
     fn load_from_str_with_valid_input() {
@@ -1933,6 +1945,15 @@ bar = f
         assert_eq!(None, iter.next());
     }
 
+    #[test]
+    fn new_has_empty_general_section() {
+        let mut ini = Ini::new();
+
+        assert!(ini.general_section().is_empty());
+        assert!(ini.general_section_mut().is_empty());
+        assert_eq!(ini.len(), 1);
+    }
+
     #[test]
     fn fix_issue63() {
         let section = "PHP";