diff --git a/tests/test_regexp.rs b/tests/test_regexp.rs
--- a/tests/test_regexp.rs
+++ b/tests/test_regexp.rs
@@ -69,6 +69,26 @@ fn test_eval_plus_dfa() {
 }
 
 #[test]
+fn test_eval_alternative_nfa() {
+	let r = Regexp::new(&String::from("a|b|c")).unwrap();
+	assert!(r.eval(String::from("a")));
+	assert!(r.eval(String::from("b")));
+	assert!(r.eval(String::from("c")));
+	assert!(!r.eval(String::from("")));
+	assert!(!r.eval(String::from("ab")));
+}
+
+#[test]
+fn test_eval_alternative_dfa() {
+	let r = Regexp::new(&String::from("a|b|c")).unwrap().determinize();
+	assert!(r.eval(String::from("a")));
+	assert!(r.eval(String::from("b")));
+	assert!(r.eval(String::from("c")));
+	assert!(!r.eval(String::from("")));
+	assert!(!r.eval(String::from("ab")));
+}
+
+#[test]
 fn test_invalid_asterisk() {
 	let x = Regexp::new(&String::from("*"));
 	assert!(matches!(x, Err(ParsingError::Asterisk{s: _, pos: 0})));
@@ -91,3 +111,21 @@ fn test_invalid_opening_parenthesis() {
 	let x = Regexp::new(&String::from("a)"));
 	assert!(matches!(x, Err(ParsingError::OpeningParenthesis{s: _, pos: 1})));
 }
+
+#[test]
+fn test_invalid_empty_variant_start() {
+	let x = Regexp::new(&String::from("a(|b)"));
+	assert!(matches!(x, Err(ParsingError::EmptyAlternativeVariant)));
+}
+
+#[test]
+fn test_invalid_empty_variant_end() {
+	let x = Regexp::new(&String::from("a|"));
+	assert!(matches!(x, Err(ParsingError::EmptyAlternativeVariant)));
+}
+
+#[test]
+fn test_invalid_empty_variant_middle() {
+	let x = Regexp::new(&String::from("a||b"));
+	assert!(matches!(x, Err(ParsingError::EmptyAlternativeVariant)));
+}