Say undefined where the SMSC named no id for a segment it took (#101)

* Cover the ids a send gets back where the SMSC named only some of them

* Say undefined where the SMSC named no id for a segment it took

* Record why the merger takes the wider type, and de-duplicate the interop narrowing

* Guard the numbering hole the merger must refuse, and correct the phase record

test/operator-receipts.test.ts

@@ -489,6 +489,38 @@ describe('an SMSC that reports each segment under an id of its own', () => {
 
 		assert.equal(sent.err, undefined);
 		assert.equal(smsc.octets.length, 3, 'every segment goes out whatever the peer answers');
-		assert.deepEqual(sent.smsIds, [id, '', '']);
+		assert.deepEqual(sent.smsIds, [id, undefined, undefined]);
+		assert.equal(sent.smsIds.length, sent.pduObjs.length, 'an entry per accepted segment, positional with pduObjs');
+	});
+
+	test('reports the segment that was named and merges nothing where the others were not', async t => {
+		const base = '01a09739-0a98-7ac0-8a9a-fcd3a7648e62';
+		const smsc = await dummySmsc(t, { messageIds: [`${base}-1`] });
+		const session = await bindToSmsc(t, smsc.port);
+		const merged: MessageDlr[] = [];
+		const reported = collect<Dlr>(1, push => { session.on('dlr', push); });
+
+		session.on('messageDlr', report => merged.push(report));
+
+		const sent = await session.sendSms({ dlr: true, message: 'x'.repeat(400), ...message });
+
+		assert.deepEqual(sent.smsIds, [`${base}-1`, undefined, undefined]);
+		smsc.deliver(receiptBody(`${base}-1`));
+
+		const [dlr] = await reported;
+
+		assert.equal(dlr?.smsId, `${base}-1`);
+		assert.deepEqual(merged, [], 'a send with an unnamed segment spells out no message to merge');
+	});
+});
+
+describe('an SMSC that answers a submit with no message id at all', () => {
+	test('reads an empty message_id as no id, on a single-segment send as much as a split one', async t => {
+		const smsc = await dummySmsc(t, { messageIds: [] });
+		const session = await bindToSmsc(t, smsc.port);
+		const sent = await session.sendSms({ dlr: true, message: 'one segment', ...message });
+
+		assert.equal(sent.err, undefined);
+		assert.deepEqual(sent.smsIds, [undefined]);
 	});
 });

test/session-extras.test.ts

@@ -2872,6 +2872,7 @@ describe('message id notation', () => {
 		assert.deepEqual(sent.smsIds, [1, 2].map(part => `${sms.smsId}-${String(part)}`));
 
 		for (const smsId of sent.smsIds) {
+			assert.ok(smsId);
 			await sendReceipt(peerOf(smpp), smsId);
 		}
 

test/session.test.ts

@@ -2498,11 +2498,18 @@ describe('merged delivery report bounds', () => {
 	test('arms nothing for a send whose ids do not number one message', () => {
 		const dlrMerger = merger();
 
-		dlrMerger.expect(['5cb0ea53b5d61093529174ca44e23871', '', '']);
+		dlrMerger.expect(['5cb0ea53b5d61093529174ca44e23871', undefined, undefined]);
 		assert.equal(dlrMerger.size, 0, 'an id the peer never named numbers nothing');
 
 		dlrMerger.expect(['bf53ad8b-1', '40ccdce2-2']);
 		assert.equal(dlrMerger.size, 0, 'nor do ids numbered off a base each');
+
+		const holed = '01a09739-0a9a-767d-ad1d-1c27667e1ca4';
+
+		// Dropping the unnamed entry rather than passing it through leaves 1 and 3 spelling out a
+		// whole 2-part message, and a send of 3 reports as delivered on two receipts.
+		dlrMerger.expect([`${holed}-1`, undefined, `${holed}-3`]);
+		assert.equal(dlrMerger.size, 0, 'nor does a hole between two parts of one base');
 	});
 
 	// A receipt for whole-3 would otherwise fill the slot whole-2 was registered for, truncating the report.