Add unit test for state diff method

raiden/tests/unit/transfer/test_state_diff.py

@@ -0,0 +1,74 @@
+import random
+from copy import deepcopy
+
+from raiden.transfer.state import (
+    ChainState,
+    NettingChannelEndState,
+    NettingChannelState,
+    PaymentNetworkState,
+    TokenNetworkState,
+    TransactionExecutionStatus,
+)
+from raiden.transfer.views import detect_balance_proof_change
+
+
+def test_detect_balance_proof_change():
+    prng = random.Random()
+    old = ChainState(prng, 1, 2, 3)
+    new = ChainState(prng, 1, 2, 3)
+
+    def diff():
+        return list(detect_balance_proof_change(old, new))
+
+    assert len(diff()) == 0
+
+    payment_network = PaymentNetworkState(b'x', [])
+    payment_network_copy = deepcopy(payment_network)
+    new.identifiers_to_paymentnetworks['a'] = payment_network
+    assert len(diff()) == 0
+
+    token_network = TokenNetworkState(b'a', b'a')
+    token_network_copy = deepcopy(token_network)
+    payment_network.tokenidentifiers_to_tokennetworks['a'] = token_network
+    assert len(diff()) == 0
+
+    channel = NettingChannelState(
+        1,
+        0,
+        b'a',
+        1,
+        1,
+        1,
+        2,
+        None,
+        None,
+        TransactionExecutionStatus(result='success'),
+    )
+    channel_copy = deepcopy(channel)
+    token_network.channelidentifiers_to_channels['a'] = channel
+    partner_state = NettingChannelEndState(b'a', 0)
+    partner_state_copy = deepcopy(partner_state)
+    channel.partner_state = partner_state
+    assert len(diff()) == 0
+
+    balance_proof = object()
+    partner_state.balance_proof = balance_proof
+    assert len(diff()) == 1
+
+    old.identifiers_to_paymentnetworks['a'] = payment_network_copy
+    assert len(diff()) == 1
+
+    payment_network_copy.tokenidentifiers_to_tokennetworks['a'] = token_network_copy
+    assert len(diff()) == 1
+
+    token_network_copy.channelidentifiers_to_channels['a'] = channel_copy
+    channel_copy.partner_state = partner_state_copy
+    assert len(diff()) == 1
+
+    channel_copy.partner_state.balance_proof = balance_proof
+    assert len(diff()) == 0
+
+    channel_copy.partner_state.balance_proof = object()
+    assert len(diff()) == 1
+
+    assert diff() == [balance_proof]