siftlode/backend/tests/test_email_html_part.py

"""Every outbound mail carries an HTML alternative, so its link is actually clickable.

The bodies are plain text and stay that way — but a bare URL in a text/plain mail is only a link if
the CLIENT chooses to linkify it. Gmail/Outlook/Apple Mail do; lighter web clients render the body
verbatim and leave the verification or password-reset link as dead text, which is the entire point of
those two messages. So `_send` now attaches an HTML part generated from the same plain body.

These are pure-logic tests except the last one, which drives the real `_send` against a fake SMTP so
the wire format itself is pinned, not just the helper.
"""

import pytest

from app import email as email_mod

_SMTP_OK = {
    "host": "smtp.example.com",
    "port": 587,
    "user": "u",
    "password": "p",
    "from": "Siftlode <u@example.com>",
}


def test_a_bare_url_becomes_a_real_link():
    # THE regression: this is what a client that does not linkify plain text was leaving as dead text.
    out = email_mod._html_body(
        "Confirm your email:\n\nhttps://siftlode.example/#verify=tok123\n\n— Siftlode"
    )
    assert '<a href="https://siftlode.example/#verify=tok123">' in out


def test_interpolated_content_cannot_inject_markup():
    # Bodies carry untrusted values — a requester's address in the admin notice, the operator contact.
    # Escaping must run BEFORE linkification, or a crafted address becomes markup in every admin's mail.
    out = email_mod._html_body('A request from <script>alert("x")</script> & co')
    assert "<script>" not in out
    assert "&lt;script&gt;" in out
    assert "&amp; co" in out


def test_a_query_string_keeps_its_escaped_ampersand_inside_the_href():
    # `&` is escaped to `&amp;` before the linkifier sees it, which is also what an HTML attribute
    # wants — so the href must carry the escaped form and nothing may be trimmed off it.
    out = email_mod._html_body("https://siftlode.example/x?a=1&b=2")
    assert (
        '<a href="https://siftlode.example/x?a=1&amp;b=2">https://siftlode.example/x?a=1&amp;b=2</a>'
        in out
    )


@pytest.mark.parametrize(
    "body,href,trail",
    [
        ("See https://siftlode.example/x.", "https://siftlode.example/x", "."),
        ("See https://siftlode.example/x, then sign in", "https://siftlode.example/x", ","),
        ("See (https://siftlode.example/x)", "https://siftlode.example/x", ")"),
    ],
)
def test_sentence_punctuation_stays_out_of_the_href(body, href, trail):
    out = email_mod._html_body(body)
    assert f'<a href="{href}">{href}</a>{trail}' in out


def test_a_token_ending_in_a_url_safe_character_is_not_trimmed():
    # token_urlsafe output can end in `-` or `_`; trimming either would hand the user a dead link.
    for tok in ("abc-", "abc_"):
        out = email_mod._html_body(f"https://siftlode.example/#reset={tok}")
        assert f'href="https://siftlode.example/#reset={tok}"' in out


def test_blank_lines_become_paragraphs_and_single_breaks_stay_inline():
    out = email_mod._html_body("Hi,\n\nline one\nline two\n\n— Siftlode")
    assert out.count("<p>") == 3
    assert "<p>line one<br>line two</p>" in out


def test_the_sent_message_is_multipart_with_the_plain_body_intact(monkeypatch):
    # The wire format, not just the helper: text/plain stays the primary part and the source of
    # truth, with text/html alongside it.
    monkeypatch.setattr(email_mod, "_smtp", lambda: _SMTP_OK)
    sent = []

    class _FakeSMTP:
        def __init__(self, *a, **kw):
            pass

        def __enter__(self):
            return self

        def __exit__(self, *a):
            return False

        def starttls(self, *a, **kw):
            pass

        def login(self, *a, **kw):
            pass

        def send_message(self, msg):
            sent.append(msg)

    monkeypatch.setattr(email_mod.smtplib, "SMTP", _FakeSMTP)

    assert (
        email_mod.send_verify_email("someone@example.com", "https://siftlode.example/#verify=tok")
        is True
    )

    (msg,) = sent
    assert msg.get_content_type() == "multipart/alternative"
    plain = msg.get_body(preferencelist=("plain",))
    rich = msg.get_body(preferencelist=("html",))
    assert plain is not None and rich is not None
    # The plain part must be byte-for-byte the template's own body — the HTML part is derived from
    # it, never a second copy that could drift.
    assert "https://siftlode.example/#verify=tok" in plain.get_content()
    assert "<a href=" not in plain.get_content()
    assert '<a href="https://siftlode.example/#verify=tok">' in rich.get_content()