Merge bitcoin/bitcoin#29514: tests: Provide more helpful assert_equal errors

a3badf7 tests: Provide more helpful assert_equal errors (Anthony Towns)

Pull request description:

  In the functional tests, we often compare dicts with assert_equal, but the output makes it very hard to tell exactly which entry in the dicts don't match when there are a lot of entries and only minor differences. Change the output to make it clearer.

ACKs for top commit:
  achow101:
    ACK a3badf7
  vasild:
    ACK a3badf7
  brunoerg:
    utACK a3badf7
  josibake:
    ACK bitcoin/bitcoin@a3badf7
  BrandonOdiwuor:
    Code Review ACK a3badf7

Tree-SHA512: 1d4b4a3b2e2e28ab09f10b41b04b52b37f64e0d8a54e2306f37de0c3eb3299a7ad4ba225b9efa67057a75e90d008a17385c810a32c9b212d240be280c2dcf2e5

Author: achow101

test/functional/test_framework/util.py

@@ -52,7 +52,24 @@ def assert_fee_amount(fee, tx_size, feerate_BTC_kvB):
         raise AssertionError("Fee of %s BTC too high! (Should be %s BTC)" % (str(fee), str(target_fee)))
 
 
+def summarise_dict_differences(thing1, thing2):
+    if not isinstance(thing1, dict) or not isinstance(thing2, dict):
+        return thing1, thing2
+    d1, d2 = {}, {}
+    for k in sorted(thing1.keys()):
+        if k not in thing2:
+            d1[k] = thing1[k]
+        elif thing1[k] != thing2[k]:
+            d1[k], d2[k] = summarise_dict_differences(thing1[k], thing2[k])
+    for k in sorted(thing2.keys()):
+        if k not in thing1:
+            d2[k] = thing2[k]
+    return d1, d2
+
 def assert_equal(thing1, thing2, *args):
+    if thing1 != thing2 and not args and isinstance(thing1, dict) and isinstance(thing2, dict):
+        d1,d2 = summarise_dict_differences(thing1, thing2)
+        raise AssertionError("not(%s == %s)\n  in particular not(%s == %s)" % (thing1, thing2, d1, d2))
     if thing1 != thing2 or any(thing1 != arg for arg in args):
         raise AssertionError("not(%s)" % " == ".join(str(arg) for arg in (thing1, thing2) + args))