diff --git a/tests/test_filter.py b/tests/test_filter.py
new file mode 100644
index 00000000..a2728ef5
--- /dev/null
+++ b/tests/test_filter.py
@@ -0,0 +1,118 @@
+import unittest
+from university-domains-list import filter
+
+
+class CountryFilterTests(unittest.TestCase):
+    def setUp(self):
+        # Sample source data
+        self.source_data = [
+            {
+                "name": "Kharkiv National University",
+                "domains": ["student.karazin.ua", "karazin.ua"],
+                "web_pages": ["https://karazin.ua"],
+                "country": "Ukraine",
+                "alpha_two_code": "UA",
+                "state-province": None
+            },
+            {
+                "name": "Universidad Técnica Federico Santa María",
+                "domains": ["usm.cl"],
+                "web_pages": ["https://usm.cl"],
+                "country": "Chile",
+                "alpha_two_code": "CL",
+                "state-province": None
+            },
+            {
+                "name": "IÉSEG School of Management",
+                "domains": ["ieseg.fr"],
+                "web_pages": ["https://ieseg.fr"],
+                "country": "France",
+                "alpha_two_code": "FR",
+                "state-province": None
+            },
+            {
+                "name": "Sun Yat-Sen University",
+                "domains": ["mail2.sysu.edu.cn", "mail.sysu.edu.cn"],
+                "web_pages": ["https://sysu.edu.cn"],
+                "country": "China",
+                "alpha_two_code": "CN",
+                "state-province": None
+            }
+        ]
+
+    def test_single_country_scope(self):
+        filtered_output = country_filter(self.source_data, "China")
+        expected_output = [
+            {
+                "name": "Sun Yat-Sen University",
+                "domains": ["mail2.sysu.edu.cn", "mail.sysu.edu.cn"],
+                "web_pages": ["https://sysu.edu.cn"],
+                "country": "China",
+                "alpha_two_code": "CN",
+                "state-province": None
+            }
+        ]
+        self.assertEqual(filtered_output, expected_output)
+
+    def test_multiple_country_scopes(self):
+        filtered_output = country_filter(self.source_data, ["China", "France"])
+        expected_output = [
+            {
+                "name": "IÉSEG School of Management",
+                "domains": ["ieseg.fr"],
+                "web_pages": ["https://ieseg.fr"],
+                "country": "France",
+                "alpha_two_code": "FR",
+                "state-province": None
+            },
+            {
+                "name": "Sun Yat-Sen University",
+                "domains": ["mail2.sysu.edu.cn", "mail.sysu.edu.cn"],
+                "web_pages": ["https://sysu.edu.cn"],
+                "country": "China",
+                "alpha_two_code": "CN",
+                "state-province": None
+            }
+        ]
+        self.assertEqual(filtered_output, expected_output)
+
+    def test_non_existent_country_scope(self):
+        filtered_output = country_filter(self.source_data, "Germany")
+        expected_output = []
+        self.assertEqual(filtered_output, expected_output)
+
+    def test_case_sensitivity(self):
+        filtered_output = country_filter(self.source_data, ["CHINA", "france"])
+        expected_output = [
+            {
+                "name": "IÉSEG School of Management",
+                "domains": ["ieseg.fr"],
+                "web_pages": ["https://ieseg.fr"],
+                "country": "France",
+                "alpha_two_code": "FR",
+                "state-province": None
+            },
+            {
+                "name": "Sun Yat-Sen University",
+                "domains": ["mail2.sysu.edu.cn", "mail.sysu.edu.cn"],
+                "web_pages": ["https://sysu.edu.cn"],
+                "country": "China",
+                "alpha_two_code": "CN",
+                "state-province": None
+            }
+        ]
+        self.assertEqual(filtered_output, expected_output)
+
+    def test_empty_source_data(self):
+        filtered_output = country_filter([], "China")
+        expected_output = []
+        self.assertEqual(filtered_output, expected_output)
+
+    def test_empty_country_scopes(self):
+        filtered_output = country_filter(self.source_data, [])
+        expected_output = self.source_data
+        self.assertEqual(filtered_output, expected_output)
+
+
+if __name__ == '__main__':
+    unittest.main()