Implement unit test for send_demo SMTP functionality

Author: orenvr

src/emailservice/test_send_demo_smtp.py

@@ -0,0 +1,34 @@
+import types
+import builtins
+from src.emailservice import send_demo
+
+class FakeSMTP:
+    def __init__(self, host, port):
+        self.host, self.port = host, port
+        self.sent = []
+    def __enter__(self): return self
+    def __exit__(self, *exc): return False
+    def send_message(self, msg):
+        self.sent.append(msg)
+
+def test_send_demo_invokes_smtp(monkeypatch):
+    captured = {"instance": None}
+
+    def fake_smtp_ctor(host, port):
+        inst = FakeSMTP(host, port)
+        captured["instance"] = inst
+        return inst
+
+    monkeypatch.setenv("SMTP_HOST", "localhost")
+    monkeypatch.setenv("SMTP_PORT", "1025")
+    monkeypatch.setattr(send_demo.smtplib, "SMTP", fake_smtp_ctor)
+
+    send_demo.main(["Oren", "[email protected]", "12345"])
+
+    inst = captured["instance"]
+    assert inst is not None
+    assert inst.host == "localhost" and inst.port == 1025
+    assert len(inst.sent) == 1
+    msg = inst.sent[0]
+    assert "Oren" in msg["To"]
+    assert "12345" in msg["Subject"]