disallow improve step for large target amount (#10)

* no improve step for large target amount * increment version
vladmelnyk · Oct 31, 2019 · 32208af · 32208af
1 parent e3e6c4b
commit 32208af
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Showing 3 changed files with 25 additions and 2 deletions.
diff --git a/build.gradle b/build.gradle
@@ -1,5 +1,5 @@
 group = 'com.coinselection'
-version = '1.1.0'
+version = '1.1.1'
 buildscript {
     ext.kotlin_version = '1.3.50'
     ext.spring_boot_version = '2.0.6.RELEASE'

diff --git a/src/main/kotlin/com.coinselection/RandomImproveCoinSelectionProvider.kt b/src/main/kotlin/com.coinselection/RandomImproveCoinSelectionProvider.kt
@@ -43,7 +43,16 @@ internal class RandomImproveCoinSelectionProvider(maxNumberOfInputs: Int, transa
                 ) ?: return null
 
         val remainingUtxoList = utxoList.subtract(dataPair.utxoList).toList()
-        val improvedUtxoList = improve(remainingUtxoList, targetValue, costCalculator, dataPair.cumulativeHolder)
+
+        val remainingTotalAmount = remainingUtxoList.sumByBigDecimal { it.amount }
+
+        val canPerformImproveStep = remainingTotalAmount > targetValue
+        val improvedUtxoList =
+                if (canPerformImproveStep) {
+                    improve(remainingUtxoList, targetValue, costCalculator, dataPair.cumulativeHolder)
+                } else {
+                    listOf()
+                }
 
         val utxoResult = dataPair.utxoList.union(improvedUtxoList).toList()
 

diff --git a/src/test/kotlin/com/coinselection/CoinSelectionProviderTest.kt b/src/test/kotlin/com/coinselection/CoinSelectionProviderTest.kt
@@ -116,6 +116,20 @@ class CoinSelectionProviderTest {
         Assertions.assertEquals(totalFeeExpected, totalFee)
     }
 
+    @Test
+    fun `should not improve for big target amount`() {
+        val targetValue = BigDecimal(27)
+        val rangeMin = 1.0
+        val rangeMax = 1.01
+        val utxoList = (1..50).map { rangeMin + (rangeMax - rangeMin) * random.nextDouble() }.map { createUnspentOutput(it) }
+        val coinSelectionResult = coinSelectionProviderRandomImprove.provide(utxoList, targetValue, smartFeePerByteHigh)
+        Assertions.assertNotNull(coinSelectionResult!!.selectedUtxos)
+        Assertions.assertTrue(coinSelectionResult.selectedUtxos!!.sumByBigDecimal { it.amount } < 28.toBigDecimal())
+        val totalFeeExpected = calculateTransactionFee(coinSelectionResult.selectedUtxos!!.size, 2, smartFeePerByteHigh)
+        val totalFee = coinSelectionResult.totalFee
+        Assertions.assertEquals(totalFeeExpected, totalFee)
+    }
+
 
     @Test
     fun `should account for op return output`() {