diff --git a/solutions/prime_number/tests_emreyilmaz.py b/solutions/prime_number/tests_emreyilmaz.py
index d2e4ebb..228c075 100644
--- a/solutions/prime_number/tests_emreyilmaz.py
+++ b/solutions/prime_number/tests_emreyilmaz.py
@@ -1,4 +1,25 @@
 from prime import is_prime
+import pytest
 
 
-# some code testing is_prime...
\ No newline at end of file
+# some code testing is_prime...
+def test_negative():
+    assert is_prime(-4) is False
+
+
+def test_prime():
+    assert is_prime(67) is True
+
+
+def test_not_prime():
+    assert is_prime(1000) is False
+
+
+def test_big_number():
+    assert is_prime(1000000) is False
+
+
+# This should fail
+def test_invalid_input():
+    with pytest.raises(TypeError):
+        assert is_prime("13") is True