What the developer wrote
Authored by Murch
test: Add SRD success tests
Previously, SRD had only failure and edge-case coverage, so we add a few
simple coin selection targets that should quickly succeed, including one
that will create a minimal change output.
What changed, and why it matters
This commit only adds new test cases for an existing coin-selection algorithm called SRD (Single Random Draw). It does not change any production wallet code, network rules, or consensus behavior. The change is purely in the test suite and verifies that SRD succeeds for simple, realistic selection targets. There is no security issue here.
No action required. This is a benign test-only commit.
Security signals we found
No strong security signals were identified.
Evidence from the diff
The diff adds a helper function TestSRDSuccess and several BOOST_AUTO_TEST_CASE invocations in src/wallet/test/coinselection_tests.cpp. These tests exercise SelectCoinsSRD with small, medium, and boundary targets, including a case designed to produce a minimal change output. No implementation code in src/wallet/coinselection.cpp or related modules is modified.
Changed components
src/wallet/test/coinselection_tests.cppInspect captured patch +18 / −0
diff --git a/src/wallet/test/coinselection_tests.cpp b/src/wallet/test/coinselection_tests.cpp
index fb3b0b19..34b71887 100644
--- a/src/wallet/test/coinselection_tests.cpp
+++ b/src/wallet/test/coinselection_tests.cpp
@@ -236,6 +236,16 @@ BOOST_AUTO_TEST_CASE(bnb_feerate_sensitivity_test)
TestBnBSuccess("Prefer two light inputs over two heavy inputs at high feerates", high_feerate_pool, /*selection_target=*/13 * CENT, /*expected_input_amounts=*/{3 * CENT, 10 * CENT}, high_feerate_params);
}
+static void TestSRDSuccess(std::string test_title, std::vector<OutputGroup>& utxo_pool, const CAmount& selection_target, const CoinSelectionParams& cs_params = default_cs_params, const int max_selection_weight = MAX_STANDARD_TX_WEIGHT)
+{
+ CAmount expected_min_amount = selection_target + cs_params.m_change_fee + CHANGE_LOWER;
+
+ const auto result = SelectCoinsSRD(utxo_pool, selection_target, cs_params.m_change_fee, cs_params.rng_fast, max_selection_weight);
+ BOOST_CHECK_MESSAGE(result, "Falsy result in SRD-Success: " + test_title);
+ const CAmount selected_effective_value = result->GetSelectedEffectiveValue();
+ BOOST_CHECK_MESSAGE(selected_effective_value >= expected_min_amount, strprintf("Selected effective value is lower than expected in SRD-Success: %s. Expected %d, but got %d", test_title, expected_min_amount, selected_effective_value));
+}
+
static void TestSRDFail(std::string test_title, std::vector<OutputGroup>& utxo_pool, const CAmount& selection_target, const CoinSelectionParams& cs_params = default_cs_params, int max_selection_weight = MAX_STANDARD_TX_WEIGHT, const bool expect_max_weight_exceeded = false)
{
const auto result = SelectCoinsSRD(utxo_pool, selection_target, cs_params.m_change_fee, cs_params.rng_fast, max_selection_weight);
@@ -255,6 +265,14 @@ BOOST_AUTO_TEST_CASE(srd_test)
AddCoins(utxo_pool, {1 * CENT, 3 * CENT, 5 * CENT}, cs_params);
+ TestSRDSuccess("Select 21k sats", utxo_pool, /*selection_target=*/21'000, cs_params);
+ TestSRDSuccess("Select 1 CENT", utxo_pool, /*selection_target=*/1 * CENT, cs_params);
+ TestSRDSuccess("Select 3.125 CENT", utxo_pool, /*selection_target=*/3'125'000, cs_params);
+ TestSRDSuccess("Select 4 CENT", utxo_pool, /*selection_target=*/4 * CENT, cs_params);
+ TestSRDSuccess("Select 7 CENT", utxo_pool, /*selection_target=*/7 * CENT, cs_params);
+
+ // The minimum change amount for SRD is the feerate dependent `change_fee` plus CHANGE_LOWER
+ TestSRDSuccess("Create minimum change", utxo_pool, /*selection_target=*/9 * CENT - cs_params.m_change_fee - CHANGE_LOWER, cs_params);
TestSRDFail("Undershoot minimum change by one sat", utxo_pool, /*selection_target=*/9 * CENT - cs_params.m_change_fee - CHANGE_LOWER + 1, cs_params);
TestSRDFail("Spend more than available", utxo_pool, /*selection_target=*/9 * CENT + 1, cs_params);
TestSRDFail("Spend everything", utxo_pool, /*selection_target=*/9 * CENT, cs_params);
Why this scored 15/100
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