test: switch invoice tests to use proper bip173 name

Signed-off-by: William Casarin <jb55@jb55.com>

tests/test_lightningd.py

@@ -348,7 +348,7 @@ class LightningDTests(BaseLightningDTests):
         inv = l1.rpc.invoice(123000, 'label', 'description')
         after = int(time.time())
         b11 = l1.rpc.decodepay(inv['bolt11'])
-        assert b11['currency'] == 'tb'
+        assert b11['currency'] == 'bcrt'
         assert b11['created_at'] >= before
         assert b11['created_at'] <= after
         assert b11['payment_hash'] == inv['payment_hash']
@@ -363,13 +363,13 @@ class LightningDTests(BaseLightningDTests):
         # Check any-amount invoice
         inv = l1.rpc.invoice("any", 'label2', 'description2')
         b11 = inv['bolt11']
-        # Amount usually comes after currency (tb in our case),
+        # Amount usually comes after currency (bcrt in our case),
         # but an any-amount invoices will have no amount
-        assert b11.startswith("lntb1")
+        assert b11.startswith("lnbcrt1")
         # By bech32 rules, the last '1' digit is the separator
         # between the human-readable and data parts. We want
-        # to match the "lntb1" above with the '1' digit as the
-        # separator, and not for example "lntb1m1....".
+        # to match the "lnbcrt1" above with the '1' digit as the
+        # separator, and not for example "lnbcrt1m1....".
         assert b11.count('1') == 1
 
     def test_invoice_expiry(self):