tests: wizard: imported addrs: validate each addr with "is_address()"

This was already done *in the GUIs*, but the backend should definitely
do at least sanity-check-level validation like this.

electrum/wizard.py

@@ -679,6 +679,11 @@ class NewWalletWizard(KeystoreWizard):
                     addresses[addr] = {'type': txin_type, 'pubkey': pubkey}
             elif 'address_list' in data:
                 for addr in data['address_list'].split():
+                    assert isinstance(addr, str)
+                    assert bitcoin.is_address(addr), f"expected bitcoin addr. got {addr[:5] + '..' + addr[-2:]}"
+                    # note: we do not normalize addresses. :/
+                    #       In particular, bech32 addresses can be either all-lowercase or all-uppercase.
+                    #       TODO we should normalize them, but it only makes sense if we also do a walletDB-upgrade.
                     addresses[addr] = {}
         elif data['keystore_type'] in ['createseed', 'haveseed']:
             seed_extension = data['seed_extra_words'] if data['seed_extend'] else ''

tests/test_wizard.py

@@ -789,11 +789,27 @@ class WalletWizardTestCase(WizardTestCase):
             {
                 "14gcRovpkCoGkCNBivQBvw7eso7eiNAbxG",
                 "35ZqQJcBQMZ1rsv8aSuJ2wkC7ohUCQMJbT",
-                "BC1QW508D6QEJXTDG4Y5R3ZARVARY0C5XW7KV8F3T4",
+                "BC1QW508D6QEJXTDG4Y5R3ZARVARY0C5XW7KV8F3T4",  # TODO normalize to lowercase?
                 "bc1pw508d6qejxtdg4y5r3zarvary0c5xw7kw508d6qejxtdg4y5r3zarvary0c5xw7kt5nd6y",
             },
         )
 
+    async def test_create_imported_wallet_from_addresses__invalid_input(self):
+        w = self._wizard_for(wallet_type='imported')
+        v = w._current
+        d = v.wizard_data
+        self.assertEqual('imported', v.view)
+
+        d.update({
+            'address_list':
+                'garbagegarbage\n'
+                '35ZqQJcBQMZ1rsv8aSuJ2wkC7ohUCQMJbT\n'
+        })
+        v = w.resolve_next(v.view, d)
+        with self.assertRaises(AssertionError) as ctx:
+            wallet = self._set_password_and_check_address(v=v, w=w, recv_addr=None)
+        self.assertTrue("expected bitcoin addr" in ctx.exception.args[0])
+
     async def test_create_imported_wallet_from_wif_keys(self):
         w = self._wizard_for(wallet_type='imported')
         v = w._current