diff --git a/tests/test_models.py b/tests/test_models.py
new file mode 100644
index 0000000..890cb44
--- /dev/null
+++ b/tests/test_models.py
@@ -0,0 +1,71 @@
+import pytest
+from src.http_convert.models import HTTPRequest, HttpMethod, OutputFormat, InputFormat
+
+
+class TestHTTPRequest:
+    def test_default_values(self):
+        request = HTTPRequest(url="https://example.com")
+        assert request.method == HttpMethod.GET
+        assert request.url == "https://example.com"
+        assert request.headers == {}
+        assert request.params == {}
+        assert request.body is None
+
+    def test_custom_values(self):
+        request = HTTPRequest(
+            method=HttpMethod.POST,
+            url="https://api.example.com/users",
+            headers={"Content-Type": "application/json"},
+            params={"page": "1"},
+            body='{"name": "test"}'
+        )
+        assert request.method == HttpMethod.POST
+        assert request.url == "https://api.example.com/users"
+        assert request.headers["Content-Type"] == "application/json"
+        assert request.params["page"] == "1"
+        assert request.body == '{"name": "test"}'
+
+    def test_get_final_url_no_params(self):
+        request = HTTPRequest(url="https://example.com/users")
+        assert request.get_final_url() == "https://example.com/users"
+
+    def test_get_final_url_with_params(self):
+        request = HTTPRequest(
+            url="https://example.com/users",
+            params={"page": "1", "limit": "10"}
+        )
+        result = request.get_final_url()
+        assert "https://example.com/users?page=1&limit=10" == result or \
+               "https://example.com/users?limit=10&page=1" == result
+
+    def test_get_final_url_with_existing_query(self):
+        request = HTTPRequest(
+            url="https://example.com/users?active=true",
+            params={"page": "1"}
+        )
+        result = request.get_final_url()
+        assert "page=1" in result
+        assert "active=true" in result
+
+
+class TestHttpMethod:
+    def test_all_methods(self):
+        assert HttpMethod.GET.value == "GET"
+        assert HttpMethod.POST.value == "POST"
+        assert HttpMethod.PUT.value == "PUT"
+        assert HttpMethod.PATCH.value == "PATCH"
+        assert HttpMethod.DELETE.value == "DELETE"
+        assert HttpMethod.HEAD.value == "HEAD"
+        assert HttpMethod.OPTIONS.value == "OPTIONS"
+
+    def test_method_from_string(self):
+        assert HttpMethod("GET") == HttpMethod.GET
+        assert HttpMethod("POST") == HttpMethod.POST
+
+
+class TestOutputFormat:
+    def test_all_formats(self):
+        assert OutputFormat.CURL.value == "curl"
+        assert OutputFormat.HTTPie.value == "httpie"
+        assert OutputFormat.FETCH.value == "fetch"
+        assert OutputFormat.AXIOS.value == "axios"