test(lexer): add decimal tests

add tests for implicit 0 decimals and normal decimals

src/math/tests/lexer.rs

@@ -6,7 +6,7 @@ use crate::math::{
 };
 
 #[test]
-pub fn test_lexer() {
+pub fn test_lexer_general() {
     let lexer = lexer::from("(1 + 2) * 3 + (5 ^ 8 % 7)");
     let tokens = lexer.collect::<Vec<_>>();
     let expected_tokens = [
@@ -31,3 +31,20 @@ pub fn test_lexer() {
         assert_eq!(tokens[i], expected_tokens[i]);
     }
 }
+
+#[test]
+pub fn test_lexer_decimals() {
+    let lexer = lexer::from("0.5 + 0.1111111111 + .5");
+    let tokens = lexer.collect::<Vec<_>>();
+    let expected_tokens = [
+        Token::Number(dec!(0.5)),
+        Token::Operator(Operator::Add),
+        Token::Number(dec!(0.1111111111)),
+        Token::Operator(Operator::Add),
+        Token::Number(dec!(0.5)),
+    ];
+
+    for i in 0..tokens.len() {
+        assert_eq!(tokens[i], expected_tokens[i]);
+    }
+}