Add transaction module

README.md

@@ -41,6 +41,7 @@ ConversionApp follows a scalable and testable architecture:
 * `feature:commission` applies dynamic commission logic (e.g. first 5 free, 0.7% after).
 * `feature:balance` manages the user's wallet-like balance.
 * `feature:settings` stores preferences like the dark theme toggle.
+* `feature:transaction` stores a history of completed exchanges.
 * `core:network`, `core:datastore`, `core:database`, and `core:designsystem` are reusable base modules shared across features.
 
 Each feature module depends only on what it needs and interacts with shared core modules through interfaces.

feature/README.md

@@ -21,3 +21,7 @@ Responsible for synchronizing currency rates from the remote API. `SyncUseCase`
 ## settings
 
 Stores user preferences such as whether dark theme is enabled. It exposes simple use cases via `settingsModule`.
+
+## transaction
+
+Stores completed exchanges so the app can show a transaction history. The module exposes simple use cases to add and retrieve `Transaction` records.

feature/transaction/.gitignore

@@ -0,0 +1 @@
+/build

feature/transaction/README.md

@@ -0,0 +1,13 @@
+# Transaction Module
+
+This module records a history of completed currency exchanges.
+
+## Overview
+- `Transaction.kt` – data model describing a single exchange.
+- `TransactionRepository` – interface for storing and retrieving transactions.
+- `TransactionDataRepository` – simple in-memory implementation.
+- `AddTransactionUseCase` – saves a transaction to the repository.
+- `GetTransactionsUseCase` – returns the stored list of transactions.
+- `transactionModule` – Koin definition exposing the repository and use cases.
+
+Use the provided use cases to persist exchanges and display the transaction list in other features.

feature/transaction/build.gradle.kts

@@ -0,0 +1,39 @@
+plugins {
+    alias(libs.plugins.android.library)
+    alias(libs.plugins.kotlin.android)
+}
+
+android {
+    namespace = "com.thesetox.transaction"
+    compileSdk = 35
+
+    defaultConfig {
+        minSdk = 24
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+        consumerProguardFiles("consumer-rules.pro")
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = false
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro",
+            )
+        }
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_11
+        targetCompatibility = JavaVersion.VERSION_11
+    }
+    kotlinOptions {
+        jvmTarget = "11"
+    }
+}
+
+dependencies {
+    implementation(libs.koin.android)
+    implementation(libs.koin.core)
+
+    testImplementation(libs.junit)
+}

feature/transaction/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

feature/transaction/src/main/kotlin/com/thesetox/transaction/AddTransactionUseCase.kt

@@ -0,0 +1,10 @@
+package com.thesetox.transaction
+
+/**
+ * Saves a transaction using [TransactionRepository].
+ */
+class AddTransactionUseCase(private val repository: TransactionRepository) {
+    operator fun invoke(transaction: Transaction) {
+        repository.saveTransaction(transaction)
+    }
+}

feature/transaction/src/main/kotlin/com/thesetox/transaction/GetTransactionsUseCase.kt

@@ -0,0 +1,8 @@
+package com.thesetox.transaction
+
+/**
+ * Returns the list of saved transactions.
+ */
+class GetTransactionsUseCase(private val repository: TransactionRepository) {
+    operator fun invoke(): List<Transaction> = repository.getTransactions()
+}

feature/transaction/src/main/kotlin/com/thesetox/transaction/Transaction.kt

@@ -0,0 +1,18 @@
+package com.thesetox.transaction
+
+/**
+ * Represents a single currency exchange transaction.
+ *
+ * @property sellCurrency Currency code being sold.
+ * @property receiveCurrency Currency code being received.
+ * @property sellAmount Amount sold in [sellCurrency].
+ * @property receiveAmount Amount received in [receiveCurrency].
+ * @property commission Fee applied to the transaction.
+ */
+data class Transaction(
+    val sellCurrency: String,
+    val receiveCurrency: String,
+    val sellAmount: Double,
+    val receiveAmount: Double,
+    val commission: Double,
+)

feature/transaction/src/main/kotlin/com/thesetox/transaction/TransactionDataRepository.kt

@@ -0,0 +1,14 @@
+package com.thesetox.transaction
+
+/**
+ * Simple in-memory implementation of [TransactionRepository].
+ */
+class TransactionDataRepository : TransactionRepository {
+    private val list = mutableListOf<Transaction>()
+
+    override fun saveTransaction(transaction: Transaction) {
+        list.add(transaction)
+    }
+
+    override fun getTransactions(): List<Transaction> = list.toList()
+}

feature/transaction/src/main/kotlin/com/thesetox/transaction/TransactionModule.kt

@@ -0,0 +1,15 @@
+package com.thesetox.transaction
+
+import org.koin.core.module.dsl.bind
+import org.koin.core.module.dsl.singleOf
+import org.koin.dsl.module
+
+/**
+ * Koin module providing transaction feature dependencies.
+ */
+val transactionModule =
+    module {
+        singleOf(::TransactionDataRepository) { bind<TransactionRepository>() }
+        singleOf(::AddTransactionUseCase)
+        singleOf(::GetTransactionsUseCase)
+    }

feature/transaction/src/main/kotlin/com/thesetox/transaction/TransactionRepository.kt

@@ -0,0 +1,12 @@
+package com.thesetox.transaction
+
+/**
+ * Repository for persisting and retrieving transactions.
+ */
+interface TransactionRepository {
+    /** Adds a new [Transaction] to the history. */
+    fun saveTransaction(transaction: Transaction)
+
+    /** Returns all recorded transactions. */
+    fun getTransactions(): List<Transaction>
+}

feature/transaction/src/test/kotlin/com/thesetox/transaction/AddTransactionUseCaseTest.kt

@@ -0,0 +1,29 @@
+package com.thesetox.transaction
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class AddTransactionUseCaseTest {
+    @Test
+    fun `transaction is added to repository`() {
+        // Arrange
+        val repository = TransactionDataRepository()
+        val addTransaction = AddTransactionUseCase(repository)
+        val getTransactions = GetTransactionsUseCase(repository)
+        val transaction =
+            Transaction(
+                sellCurrency = "EUR",
+                receiveCurrency = "USD",
+                sellAmount = 10.0,
+                receiveAmount = 12.0,
+                commission = 0.07,
+            )
+
+        // Act
+        addTransaction(transaction)
+        val result = getTransactions()
+
+        // Assert
+        assertEquals(listOf(transaction), result)
+    }
+}

settings.gradle.kts

@@ -35,3 +35,4 @@ include(":feature:exchange")
 include(":feature:balance")
 include(":feature:comission")
 include(":feature:settings")
+include(":feature:transaction")