diff --git a/tests/test_parser.py b/tests/test_parser.py
new file mode 100644
index 0000000..a88b31d
--- /dev/null
+++ b/tests/test_parser.py
@@ -0,0 +1,133 @@
+"""Tests for the parser module."""
+
+import pytest
+
+from regex_humanizer.parser import (
+    tokenize,
+    parse_regex,
+    ParseError,
+    Literal,
+    CharacterClass,
+    Quantifier,
+    Group,
+    Alternation,
+    Anchor,
+    SpecialSequence,
+)
+
+
+class TestTokenizer:
+    def test_tokenize_literal(self):
+        tokens = tokenize("abc")
+        assert len(tokens) == 1
+        assert tokens[0].type == "LITERAL"
+        assert tokens[0].value == "abc"
+
+    def test_tokenize_anchors(self):
+        tokens = tokenize("^test$")
+        assert len(tokens) == 3
+        assert tokens[0].type == "ANCHOR_START"
+        assert tokens[1].type == "LITERAL"
+        assert tokens[2].type == "ANCHOR_END"
+
+    def test_tokenize_quantifiers(self):
+        tokens = tokenize("a*")
+        assert len(tokens) == 2
+        assert tokens[0].type == "LITERAL"
+        assert tokens[1].type == "STAR"
+
+    def test_tokenize_character_class(self):
+        tokens = tokenize("[abc]")
+        assert len(tokens) >= 2
+        assert tokens[0].type == "OPEN_BRACKET"
+        assert tokens[-1].type == "CLOSE_BRACKET"
+
+    def test_tokenize_groups(self):
+        tokens = tokenize("(abc)")
+        assert len(tokens) == 3
+        assert tokens[0].type == "OPEN_GROUP"
+        assert tokens[1].type == "LITERAL"
+        assert tokens[2].type == "CLOSE_GROUP"
+
+    def test_tokenize_alternation(self):
+        tokens = tokenize("a|b")
+        assert len(tokens) == 3
+        assert tokens[0].type == "LITERAL"
+        assert tokens[1].type == "ALTERNATION"
+        assert tokens[2].type == "LITERAL"
+
+
+class TestParser:
+    def test_parse_literal(self):
+        ast = parse_regex("hello")
+        assert len(ast) == 1
+        assert isinstance(ast[0], Literal)
+        assert ast[0].value == "hello"
+
+    def test_parse_character_class(self):
+        ast = parse_regex("[abc]")
+        assert len(ast) == 1
+        assert isinstance(ast[0], CharacterClass)
+
+    def test_parse_inverted_class(self):
+        ast = parse_regex("[^abc]")
+        assert len(ast) == 1
+        assert isinstance(ast[0], CharacterClass)
+        assert ast[0].inverted is True
+
+    def test_parse_quantifier_star(self):
+        ast = parse_regex("a*")
+        assert len(ast) == 1
+        assert isinstance(ast[0], Quantifier)
+
+    def test_parse_quantifier_plus(self):
+        ast = parse_regex("a+")
+        assert len(ast) == 1
+        assert isinstance(ast[0], Quantifier)
+
+    def test_parse_quantifier_question(self):
+        ast = parse_regex("a?")
+        assert len(ast) == 1
+        assert isinstance(ast[0], Quantifier)
+
+    def test_parse_group(self):
+        ast = parse_regex("(abc)")
+        assert len(ast) == 1
+        assert isinstance(ast[0], Group)
+        assert len(ast[0].content) == 1
+
+    def test_parse_non_capturing_group(self):
+        ast = parse_regex("(?:abc)")
+        assert len(ast) == 1
+        assert isinstance(ast[0], Group)
+        assert ast[0].capturing is False
+
+    def test_parse_alternation(self):
+        ast = parse_regex("a|b")
+        assert len(ast) == 1
+        assert isinstance(ast[0], Alternation)
+        assert len(ast[0].options) == 2
+
+    def test_parse_anchors(self):
+        ast = parse_regex("^start$")
+        assert len(ast) == 3
+        assert isinstance(ast[0], Anchor)
+        assert isinstance(ast[2], Anchor)
+
+    def test_parse_special_sequences(self):
+        ast = parse_regex(r"\d+\w+")
+        assert len(ast) == 2
+        assert isinstance(ast[0], Quantifier)
+
+    def test_parse_complex_pattern(self):
+        pattern = r"^\w+@[a-z]+\.[a-z]+$"
+        ast = parse_regex(pattern)
+        assert len(ast) > 0
+
+    def test_parse_error_unclosed_bracket(self):
+        with pytest.raises(ParseError):
+            parse_regex("[abc")
+
+    def test_parse_error_unclosed_group(self):
+        with pytest.raises(ParseError):
+            parse_regex("(abc")