Implemented calculating TotalAmounts from invoice items

e-invoice-domain/src/main/kotlin/net/codinux/invoicing/calculator/AmountsCalculator.kt

@@ -1,16 +1,23 @@
 package net.codinux.invoicing.calculator
 
 import net.codinux.invoicing.mapper.MustangMapper
-import net.codinux.invoicing.model.Invoice
-import net.codinux.invoicing.model.TotalAmounts
+import net.codinux.invoicing.model.*
 import org.mustangproject.ZUGFeRD.IExportableTransaction
 import org.mustangproject.ZUGFeRD.TransactionCalculator
 import java.math.BigDecimal
+import java.time.LocalDate
 
 open class AmountsCalculator {
 
     protected open val mapper by lazy { MustangMapper() } // lazy to avoid circular dependency creation with MustangMapper
 
+    private val invoiceDetails by lazy { InvoiceDetails("", LocalDate.now()) }
+
+    private val party by lazy { Party("", "", null, null, "") }
+
+
+    open fun calculateTotalAmounts(items: List<InvoiceItem>) =
+        calculateTotalAmounts(Invoice(invoiceDetails, party, party, items))
 
     open fun calculateTotalAmounts(invoice: Invoice) =
         calculateTotalAmounts(mapper.mapToTransaction(invoice))

e-invoice-domain/src/test/kotlin/net/codinux/invoicing/calculator/AmountsCalculatorTest.kt

@@ -0,0 +1,38 @@
+package net.codinux.invoicing.calculator
+
+import assertk.assertThat
+import assertk.assertions.isEqualByComparingTo
+import assertk.assertions.isEqualTo
+import net.codinux.invoicing.model.InvoiceItem
+import java.math.BigDecimal
+import java.math.RoundingMode
+import kotlin.test.Test
+
+class AmountsCalculatorTest {
+
+    private val underTest = AmountsCalculator()
+
+
+    @Test
+    fun calculateTotalAmounts() {
+        val items = listOf(
+            InvoiceItem("", BigDecimal(7), "", BigDecimal(5), BigDecimal(19)),
+            InvoiceItem("", BigDecimal(20), "", BigDecimal(5), BigDecimal(7)),
+        )
+
+        val result = underTest.calculateTotalAmounts(items)
+
+        val expectedNetAmount = BigDecimal(7 * 5 + 20 * 5).setScale(2)
+        val expectedVatAmount = BigDecimal(7 * 5 * 0.19 + 20 * 5 * 0.07).setScale(2, RoundingMode.DOWN)
+        val expectedTotalAmount = expectedNetAmount + expectedVatAmount
+
+        assertThat(result.lineTotalAmount).isEqualByComparingTo(expectedNetAmount)
+        assertThat(result.taxBasisTotalAmount).isEqualByComparingTo(expectedNetAmount)
+
+        assertThat(result.taxTotalAmount).isEqualTo(expectedVatAmount)
+
+        assertThat(result.grandTotalAmount).isEqualTo(expectedTotalAmount)
+        assertThat(result.duePayableAmount).isEqualTo(expectedTotalAmount)
+    }
+
+}