Exclude empty and zero content references

test/content-references.test.js

@@ -120,4 +120,43 @@ test('content references omit built-in font stacks but retain managed font famil
   assert.deepEqual(references.map(reference => [reference.owner_key, reference.reference_value]), [
     ['managed', 'ubuntu regular']
   ]);
+});
+
+test('content references omit zero and empty item selections for every typed reference field', () => {
+  const fields = ['source_id', 'feed_id', 'timetable_group_id', 'weather_location_id', 'weather_icon_set_id'];
+  for (const field of fields) {
+    for (const value of [0, '0', ' 0 ', '', ' ', null, undefined]) {
+      assert.deepEqual(collectContentReferences('slide', 117, { empty: { [field]: value } }), [], field + ': ' + String(value));
+    }
+  }
+  for (const field of fields.slice(0, -1)) {
+    for (const value of ['00', '0.0', '-0']) {
+      assert.deepEqual(collectContentReferences('template', 42, { empty: { [field]: value } }), [], field + ': ' + value);
+    }
+  }
+});
+
+test('content reference replacement removes stored zero selections while preserving valid references', async () => {
+  const calls = [];
+  const connection = {
+    async query(sql, params) {
+      calls.push([sql, params]);
+      if (sql.startsWith('SELECT id, owner_key')) {
+        return [[
+          { id: 101, owner_key: 'api', reference_type: 'api-request', reference_value: '0' },
+          { id: 102, owner_key: 'feed', reference_type: 'rss-feed', reference_value: '8' }
+        ]];
+      }
+      return [{}];
+    }
+  };
+
+  await replaceContentReferences(connection, 'slide', 117, {
+    api: { source_id: 0 },
+    feed: { feed_id: 8 }
+  });
+
+  const deletion = calls.find(([sql]) => sql.startsWith('DELETE FROM c_content_references'));
+  assert.deepEqual(deletion[1], ['slide', 117, [101]]);
+  assert.ok(!calls.some(([sql]) => sql.startsWith('INSERT')));
 });