Add unit test suite with pytest configuration

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/unit/test_email_helpers.py

@@ -0,0 +1,38 @@
+"""Tests for email helper functions in blueprints/email/helpers.py."""
+
+from blueprints.email.helpers import generate_email_token, get_user_email_address
+
+
+class TestGenerateEmailToken:
+    def test_returns_16_char_hex(self):
+        token = generate_email_token("user-123", "my-secret")
+        assert len(token) == 16
+        assert all(c in "0123456789abcdef" for c in token)
+
+    def test_deterministic(self):
+        t1 = generate_email_token("user-123", "my-secret")
+        t2 = generate_email_token("user-123", "my-secret")
+        assert t1 == t2
+
+    def test_different_users_different_tokens(self):
+        t1 = generate_email_token("user-1", "secret")
+        t2 = generate_email_token("user-2", "secret")
+        assert t1 != t2
+
+    def test_different_secrets_different_tokens(self):
+        t1 = generate_email_token("user-1", "secret-a")
+        t2 = generate_email_token("user-1", "secret-b")
+        assert t1 != t2
+
+
+class TestGetUserEmailAddress:
+    def test_formats_correctly(self):
+        addr = get_user_email_address("abc123", "example.com")
+        assert addr == "ask+abc123@example.com"
+
+    def test_preserves_token(self):
+        token = "deadbeef12345678"
+        addr = get_user_email_address(token, "mail.test.org")
+        assert token in addr
+        assert addr.startswith("ask+")
+        assert "@mail.test.org" in addr