diff --git a/tests/test_parsers.py b/tests/test_parsers.py
new file mode 100644
index 0000000..eb08f15
--- /dev/null
+++ b/tests/test_parsers.py
@@ -0,0 +1,174 @@
+import pytest
+from pathlib import Path
+import tempfile
+import os
+
+from config_auditor.discovery import ConfigDiscovery
+from config_auditor.parsers import ParserFactory, JsonParser, YamlParser, TomlParser
+from config_auditor.rules import (
+    RuleRegistry,
+    DeprecatedPackageRule,
+    OutdatedVersionRule,
+    MissingTypeCheckingRule,
+    SecurityVulnerabilityRule,
+    MissingScriptsRule,
+    PythonProjectMetaRule,
+)
+
+
+class TestConfigDiscovery:
+    def test_discover_json_files(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            (Path(tmpdir) / "package.json").write_text('{"name": "test"}')
+            (Path(tmpdir) / "tsconfig.json").write_text('{"compilerOptions": {}}')
+
+            discovery = ConfigDiscovery(max_depth=2)
+            configs = discovery.discover(Path(tmpdir))
+
+            assert len(configs) >= 2
+
+    def test_discover_nested_files(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            nested = Path(tmpdir) / "src"
+            nested.mkdir()
+            (nested / "tsconfig.json").write_text('{"compilerOptions": {}}')
+
+            discovery = ConfigDiscovery(max_depth=3)
+            configs = discovery.discover(Path(tmpdir))
+
+            assert len(configs) == 1
+
+    def test_no_files_found(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            discovery = ConfigDiscovery(max_depth=2)
+            configs = discovery.discover(Path(tmpdir))
+
+            assert len(configs) == 0
+
+
+class TestParsers:
+    def test_json_parse_valid(self):
+        parser = JsonParser()
+        content = '{"name": "test", "version": "1.0.0"}'
+        result = parser.parse(content)
+
+        assert result is not None
+        assert result["name"] == "test"
+        assert result["version"] == "1.0.0"
+
+    def test_json_parse_invalid(self):
+        parser = JsonParser()
+        content = "not valid json"
+        result = parser.parse(content)
+
+        assert result is None
+
+    def test_yaml_parse_valid(self):
+        parser = YamlParser()
+        content = "key: value\nlist:\n  - item1\n  - item2"
+        result = parser.parse(content)
+
+        assert result is not None
+        assert result["key"] == "value"
+        assert len(result["list"]) == 2
+
+    def test_toml_parse_valid(self):
+        parser = TomlParser()
+        content = 'name = "test"\nversion = "1.0.0"'
+        result = parser.parse(content)
+
+        assert result is not None
+        assert result["name"] == "test"
+
+    def test_parser_factory(self):
+        factory = ParserFactory()
+
+        json_result = factory.parse("json", '{"test": true}')
+        assert json_result is not None
+
+        yaml_result = factory.parse("yaml", "test: value")
+        assert yaml_result is not None
+
+        toml_result = factory.parse("toml", 'test = true')
+        assert toml_result is not None
+
+
+class TestRules:
+    def test_deprecated_package_rule(self):
+        rule = DeprecatedPackageRule()
+        data = {"dependencies": {"request": "^2.0.0"}}
+        result = rule.evaluate(data, Path("package.json"))
+
+        assert result.passed is False
+        assert "deprecated" in result.message.lower()
+
+    def test_no_deprecated_packages(self):
+        rule = DeprecatedPackageRule()
+        data = {"dependencies": {"express": "^4.0.0"}}
+        result = rule.evaluate(data, Path("package.json"))
+
+        assert result.passed is True
+
+    def test_outdated_version_rule(self):
+        rule = OutdatedVersionRule()
+        data = {"dependencies": {"express": "^0.1.0"}}
+        result = rule.evaluate(data, Path("package.json"))
+
+        assert result.passed is False
+
+    def test_missing_type_checking_rule(self):
+        rule = MissingTypeCheckingRule()
+        data = {"compilerOptions": {"strict": False}}
+        result = rule.evaluate(data, Path("tsconfig.json"))
+
+        assert result.passed is False
+
+    def test_strict_mode_enabled(self):
+        rule = MissingTypeCheckingRule()
+        data = {"compilerOptions": {"strict": True}}
+        result = rule.evaluate(data, Path("tsconfig.json"))
+
+        assert result.passed is True
+
+    def test_missing_scripts_rule(self):
+        rule = MissingScriptsRule()
+        data = {"scripts": {}}
+        result = rule.evaluate(data, Path("package.json"))
+
+        assert result.passed is False
+
+    def test_all_scripts_present(self):
+        rule = MissingScriptsRule()
+        data = {"scripts": {"test": "jest", "build": "tsc"}}
+        result = rule.evaluate(data, Path("package.json"))
+
+        assert result.passed is True
+
+    def test_python_project_meta_rule(self):
+        rule = PythonProjectMetaRule()
+        data = {"tool": {"poetry": {"name": "test", "version": "1.0.0"}}}
+        result = rule.evaluate(data, Path("pyproject.toml"))
+
+        assert result.passed is True
+
+
+class TestRuleRegistry:
+    def test_evaluate_json_config(self):
+        registry = RuleRegistry()
+        data = {
+            "dependencies": {"request": "^2.0.0"},
+            "scripts": {}
+        }
+        issues = registry.evaluate("json", data, Path("package.json"))
+
+        issue_categories = [i.category for i in issues]
+        assert "deprecated-package" in issue_categories
+        assert "missing-scripts" in issue_categories
+
+    def test_empty_config_has_warnings(self):
+        registry = RuleRegistry()
+        issues = registry.evaluate("json", {}, Path("package.json"))
+
+        assert len(issues) > 0
+        categories = [i.category for i in issues]
+        assert "missing-scripts" in categories