resolve multiple chars in a char, tests for it

parser/src/tokenizer/lexer.rs

@@ -114,6 +114,10 @@ impl Token {
         if unicode {
             let string = input_tendril.to_string();
             let unicode_number = &string[3..string.len() - 1];
+            let len = unicode_number.len();
+            if !(1..=6).contains(&len) {
+                return None;
+            }
 
             if let Ok(hex) = u32::from_str_radix(&unicode_number, 16) {
                 if let Some(character) = std::char::from_u32(hex) {
@@ -122,7 +126,9 @@ impl Token {
             }
         }
 
-        if let Some(character) = input_tendril.to_string().chars().next() {
+        if input_tendril.to_string().chars().count() != 1 {
+            return None;
+        } else if let Some(character) = input_tendril.to_string().chars().next() {
             return Some(character);
         }
 

tests/expectations/parser/parser/expression/literal/char_fail.leo.out

@@ -6,3 +6,7 @@ outputs:
   - "    --> test:1:1\n     |\n   1 | 'a\n     | ^\n     |\n     = unexpected token: '''"
   - "    --> test:1:1\n     |\n   1 | ''\n     | ^\n     |\n     = unexpected token: '''"
   - "    --> test:1:1\n     |\n   1 | '\\x9'\n     | ^\n     |\n     = unexpected token: '''"
+  - "    --> test:1:1\n     |\n   1 | 'abcdefg'\n     | ^\n     |\n     = unexpected token: '''"
+  - "    --> test:1:1\n     |\n   1 | '\\t\\t'\n     | ^\n     |\n     = unexpected token: '''"
+  - "    --> test:1:1\n     |\n   1 | '\\u{bbbbb}\\u{aaaa}'\n     | ^\n     |\n     = unexpected token: '''"
+  - "    --> test:1:1\n     |\n   1 | '😭😂😘'\n     | ^\n     |\n     = unexpected token: '''"

tests/parser/expression/literal/char_fail.leo

@@ -10,3 +10,11 @@ expectation: Fail
 ''
 
 '\x9'
+
+'abcdefg'
+
+'\t\t'
+
+'\u{bbbbb}\u{aaaa}'
+
+'😭😂😘'