- added more unit tests for lexer

- corrected defects revealed by added tests

tests/test_lex.rs

@@ -2,13 +2,47 @@ mod lex_tests {
     use relish::ast::{lex};
 
     #[test]
-    fn test_lex_basic_list() {
-        let document: &str = "(hello \"world\")";
+    fn test_lex_basic_pair() {
+        let document: &str = "(hello 'world')";
+        let output: &str = "(hello 'world' nil)";
         match lex(document.to_string()) {
             Ok(box_cell) => {
-                assert_eq!(format!("{}", *box_cell), document.to_string());
+                assert_eq!(format!("{}", *box_cell), output.to_string());
             },
-            Err(_s) => assert!(false)
+            Err(s) => {
+                print!("{}\n", s);
+                assert!(false);
+            }
+        }
+    }
+
+    #[test]
+    fn test_lex_basic_list() {
+        let document: &str = "(hello 'world' 1 2 3)";
+        let output: &str = "(hello 'world' 1 2 3 nil)";
+        match lex(document.to_string()) {
+            Ok(box_cell) => {
+                assert_eq!(format!("{}", *box_cell), output.to_string());
+            },
+            Err(s) => {
+                print!("{}\n", s);
+                assert!(false);
+            }
+        }
+    }
+
+    #[test]
+    fn test_lex_complex_list() {
+        let document: &str = "(hello 'world' (1 2 (1 2 3)) 1 2 3)";
+        let output: &str = "(hello 'world' (1 2 (1 2 3 nil) nil) 1 2 3 nil)";
+        match lex(document.to_string()) {
+            Ok(box_cell) => {
+                assert_eq!(format!("{}", *box_cell), output.to_string());
+            },
+            Err(s) => {
+                print!("{}\n", s);
+                assert!(false);
+            }
         }
     }
 }