test: Add coverage for getchaintxstats in assumeutxo context

test/functional/feature_assumeutxo.py

@@ -247,14 +247,26 @@ def check_tx_counts(final: bool) -> None:
             the snapshot, and final values after the snapshot is validated."""
             for height, block in blocks.items():
                 tx = n1.getblockheader(block.hash)["nTx"]
-                chain_tx = n1.getchaintxstats(nblocks=1, blockhash=block.hash).get("txcount", None)
+                stats = n1.getchaintxstats(nblocks=1, blockhash=block.hash)
+                chain_tx = stats.get("txcount", None)
+                window_tx_count = stats.get("window_tx_count", None)
+                tx_rate = stats.get("txrate", None)
+                window_interval = stats.get("window_interval")
 
                 # Intermediate nTx of the starting block should be set, but nTx of
                 # later blocks should be 0 before they are downloaded.
+                # The window_tx_count of 1 block is equal to the blocks tx count.
+                # If the tx count would be 0 the value is missing.
+                # If tx_rate is calculated from window_tx_count and window_interval
+                # when possible.
                 if final or height == START_HEIGHT:
                     assert_equal(tx, block.tx)
+                    assert_equal(window_tx_count, tx)
+                    if window_interval > 0:
+                        assert_equal(tx_rate, window_tx_count/window_interval)
                 else:
                     assert_equal(tx, 0)
+                    assert_equal(window_tx_count, None)
 
                 # Intermediate nChainTx of the starting block and snapshot block
                 # should be set, but others should be None until they are downloaded.