Add cursor tests

boa/src/syntax/lexer/tests.rs

@@ -588,6 +588,71 @@ fn take_while_ascii_pred_entire_str() {
     assert_eq!(str::from_utf8(buf.as_slice()).unwrap(), "abcdefghijk");
 }
 
+#[test]
+fn take_while_ascii_pred_non_ascii_stop() {
+    let mut cur = Cursor::new("abcde😀fghijk".as_bytes());
+
+    let mut buf: Vec<u8> = Vec::new();
+
+    cur.take_while_ascii_pred(&mut buf, &|_| true).unwrap();
+
+    assert_eq!(str::from_utf8(buf.as_slice()).unwrap(), "abcde");
+}
+
+#[test]
+fn take_while_char_pred_simple() {
+    let mut cur = Cursor::new(&b"abcdefghijk"[..]);
+
+    let mut buf: Vec<u8> = Vec::new();
+
+    cur.take_while_char_pred(&mut buf, &|c| {
+        c == 'a' as u32 || c == 'b' as u32 || c == 'c' as u32
+    })
+    .unwrap();
+
+    assert_eq!(str::from_utf8(buf.as_slice()).unwrap(), "abc");
+}
+
+#[test]
+fn take_while_char_pred_immediate_stop() {
+    let mut cur = Cursor::new(&b"abcdefghijk"[..]);
+
+    let mut buf: Vec<u8> = Vec::new();
+
+    cur.take_while_char_pred(&mut buf, &|_| false).unwrap();
+
+    assert_eq!(str::from_utf8(buf.as_slice()).unwrap(), "");
+}
+
+#[test]
+fn take_while_char_pred_entire_str() {
+    let mut cur = Cursor::new(&b"abcdefghijk"[..]);
+
+    let mut buf: Vec<u8> = Vec::new();
+
+    cur.take_while_char_pred(&mut buf, &|_| true).unwrap();
+
+    assert_eq!(str::from_utf8(buf.as_slice()).unwrap(), "abcdefghijk");
+}
+
+#[test]
+fn take_while_char_pred_utf8_char() {
+    let mut cur = Cursor::new("abc😀defghijk".as_bytes());
+
+    let mut buf: Vec<u8> = Vec::new();
+
+    cur.take_while_char_pred(&mut buf, &|c| {
+        if let Ok(c) = char::try_from(c) {
+            c == 'a' || c == 'b' || c == 'c' || c == '😀'
+        } else {
+            false
+        }
+    })
+    .unwrap();
+
+    assert_eq!(str::from_utf8(buf.as_slice()).unwrap(), "abc😀");
+}
+
 #[test]
 fn illegal_following_numeric_literal() {
     // Checks as per https://tc39.es/ecma262/#sec-literals-numeric-literals that a NumericLiteral cannot