diff --git a/Week05/test_emails_yasin_soytas.py b/Week05/test_emails_yasin_soytas.py
new file mode 100644
index 00000000..c0f0f379
--- /dev/null
+++ b/Week05/test_emails_yasin_soytas.py
@@ -0,0 +1,55 @@
+import pytest
+from emails_yasin_soytas import Emails
+
+
+def test_class_exists():
+    assert Emails is not None
+
+
+def test_is_subclass_of_list():
+    assert issubclass(Emails, list)
+
+
+def test_empty_constructor():
+    e = Emails()
+    assert isinstance(e, list)
+    assert len(e) == 0
+
+
+def test_valid_emails_added():
+    emails = Emails(["test@example.com", "user@mail.com"])
+    assert "test@example.com" in emails
+    assert "user@mail.com" in emails
+    assert len(emails) == 2
+
+
+def test_emails_lowercase():
+    emails = Emails(["TEST@EXAMPLE.COM"])
+    assert "test@example.com" in emails
+
+
+def test_no_duplicates():
+    emails = Emails(["test@example.com", "TEST@EXAMPLE.COM"])
+    assert len(emails) == 1
+
+
+def test_invalid_emails_not_added():
+    emails = Emails(["testexample.com", 123, None, "hello"])
+    assert len(emails) == 0
+
+
+def test_mixed_input():
+    emails = Emails([
+        "A@A.COM",
+        "b@b.com",
+        "invalid",
+        42,
+        "a@a.com"
+    ])
+    assert emails == ["a@a.com", "b@b.com"]
+
+
+
+def test_instance_type():
+    emails = Emails(["x@y.com"])
+    assert isinstance(emails, Emails)