EMAIL-WP-0005 T05/T06: evidence realism and harness documentation
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Adds harness.deliver_raw() to inject crafted .eml fixtures through the harness,
so they pick up the real Received: headers an MTA adds, and
harness.inject_maildir() as the byte-exact offline counterpart.

tests/test_evidence_realism.py asserts all ten recognized evidence classes
after passing through a real MTA, proves MTA delivery does not change which
evidence is produced, and covers Maildir injection offline.

Documents what no local server can honestly produce -- provider-generated DSNs,
real 4xx deferral and retry, ISP feedback loops, provider suppression behavior,
MX acceptance as distinct from provider acceptance -- and names SES simulator
addresses as the staging path. That tier stays out of the test run because it
needs real credentials.

Adds docs/test-harness-tutorial.md covering the three test tiers and the
start/send/scan/assert/reset walkthrough, with an explicit
assertable/not-assertable list so the evidence ceiling is stated where tests
get written. Adds a Maildir section to the mailbox report tutorial.

Completes EMAIL-WP-0005. Suite: 85 passed with the harness up, 64 passed +
21 skipped with it down.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
This commit is contained in:
tegwick 2026-08-14 02:00:17 +02:00
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# Test Harness Tutorial
How to run `email-connect` against a local mail server: start it, send through
it, scan it back, assert on the result, and reset between tests.
Reference material lives in `tests/harness/README.md`. This page is the
walkthrough.
## 1. The three test tiers
`email-connect` tests at three levels, and it matters which one a given
assertion belongs to.
| Tier | Source | Needs | What it is for |
| --- | --- | --- | --- |
| Unit | `.eml` fixtures, temporary Maildir trees | nothing | Parsing, classification, reporting. Deterministic and offline. |
| Integration | local GreenMail harness | Docker | Send-to-scan continuity through a real SMTP/IMAP server. |
| Provider staging | real provider account | credentials, operator | Behavior only a real provider and remote MX produce. |
The default `pytest` run is the unit tier plus any integration tests whose
harness happens to be up. Nothing in the default run requires a container: with
the harness down the integration cases skip.
The staging tier is not wired into the test run at all. It needs real
credentials, which are routed through OpenBao — see
`.claude/rules/credential-routing.md` — and must never be pointed at the
harness.
## 2. Start the harness
```bash
docker compose -f tests/harness/docker-compose.yml up -d
docker inspect --format '{{.State.Health.Status}}' email-connect-harness
```
Wait for `healthy`. The container serves SMTP on 3025 and IMAP on 3143, both
bound to `127.0.0.1` only.
## 3. Give the test a mailbox
Authentication is disabled and mailboxes are created on first login, so there is
no provisioning step — pick an address and use it:
```python
import harness
recipient = harness.address("invitation delivered")
# -> invitation-delivered@harness.email-connect.test
```
Slugging the test's own name keeps two tests from colliding. The domain is under
`.test`, reserved by RFC 2606, so a stray send cannot leave the host.
## 4. Send through the service
```python
from email_connect.transactional import SQLiteDeliveryStore, TransactionalApplication
app = TransactionalApplication(
SQLiteDeliveryStore(str(tmp_path / "mail.db")),
harness.smtp_provider(),
"harness-ingest-token",
"https://users.harness.email-connect.test",
)
```
`harness.smtp_provider()` returns a real `SMTPProvider` in plaintext transport
mode. GreenMail offers no STARTTLS, and `SMTPProvider` permits plaintext only
for loopback hosts, so this cannot be pointed at a real provider by accident.
## 5. Scan it back
```python
from email_connect.scanner import scan_mailbox
config = harness.mailbox_config(
recipient,
storage_path=str(tmp_path / "state.sqlite"),
reports_dir=str(tmp_path / "reports"),
)
result = scan_mailbox(config)
```
From the command line:
```bash
export EMAIL_CONNECT_IMAP_USER=invitation-delivered@harness.email-connect.test
export EMAIL_CONNECT_IMAP_PASSWORD=harness
email-connect scan-mailbox --config config/harness-imap.yml --out reports/
```
## 6. Assert — and what you may not assert
An accepted send is `provider_accepted`. A message sitting in a harness mailbox
is a message sitting in a harness mailbox. Neither is evidence of inbox
placement, recipient awareness, identity, or authorization, and a test that
asserts otherwise is wrong even when it passes.
Assertable:
```python
assert body["evidence_ceiling"] == "provider_accepted"
assert body["reference"] == str(messages[0]["Message-ID"]).strip()
assert len(delivered_messages(recipient)) == 1
```
Not assertable from harness mail — these are the claims the repo exists to
avoid:
```text
the recipient received it
the recipient read it
the recipient's identity is confirmed
the recipient is authorized
the intended result was satisfied
```
`coordination-engine` evaluates results. `email-connect` reports what the email
channel observed.
## 7. Reset between tests
```python
def test_something():
harness.reset()
...
```
`harness.reset()` drops every user and message; the next login recreates the
mailbox empty. Call it at the **start** of a test so a crashed or interrupted
run cannot leave state for the next one. It is global, so tests that reset
cannot run in parallel against a single harness.
## 8. Bounces, complaints and deferrals
The harness accepts everything, so it never produces these on its own. Inject a
crafted fixture instead:
```python
harness.deliver_raw(recipient, (FIXTURES / "hard_bounce.eml").read_bytes())
```
Injected messages still travel through a real MTA and pick up real `Received:`
headers — which is how `EMAIL-WP-0005-T04` caught a reply heuristic that was
matching those headers and labelling ordinary mail a human reply.
`harness.inject_maildir()` is the offline counterpart, writing straight into a
Maildir tree with no MTA and no harness.
Provider-generated DSNs, real deferral and retry, ISP feedback loops, and
provider suppression behavior are **not** reachable locally. See the
provider-simulator table in `tests/harness/README.md`.
## 9. Stop the harness
```bash
docker compose -f tests/harness/docker-compose.yml down -v
```
Then confirm the default suite is still offline and green:
```bash
pytest tests/ -q # integration cases skip
```