Add tests for money exchange

src/main/kotlin/com/cubetiqs/libra/moneyutils/Money.kt

@@ -1,7 +1,28 @@
 package com.cubetiqs.libra.moneyutils
 
-data class Money(
+open class Money(
     var value: Double,
-    var currency: String = "USD"
-)
+    private var currency: String = "USD"
+) : StdMoney {
 
+    //////////////////// - PROPERTIES - ////////////////////
+
+    override fun getMoneyValue(): Double {
+        return this.value
+    }
+
+    override fun getMoneyCurrency(): String {
+        return this.currency.toUpperCase()
+    }
+
+    //////////////////// - GENERIC - ////////////////////
+
+    override fun toString(): String {
+        return "Money(value=${getMoneyValue()}, currency='${getMoneyCurrency()}')"
+    }
+
+    companion object {
+        val ZERO: StdMoney
+            get() = Money(value = 0.0)
+    }
+}

src/main/kotlin/com/cubetiqs/libra/moneyutils/MoneyConfig.kt

@@ -15,6 +15,8 @@ object MoneyConfig {
      * Value is the rate
      */
     private val config: MutableMap<String, Double> = mutableMapOf()
+    private var valid: Boolean = false
+    fun isValid() = valid
 
     /**
      * Money properties for money config format
@@ -56,6 +58,9 @@ object MoneyConfig {
                 throw MoneyCurrencyStateException("money config format is not valid!")
             }
         }
+
+        // validate the config is load or not
+        this.valid = this.config.isNotEmpty()
     }
 
     // all currencies with its rate

src/main/kotlin/com/cubetiqs/libra/moneyutils/MoneyExchangeUtils.kt

@@ -0,0 +1,13 @@
+package com.cubetiqs.libra.moneyutils
+
+object MoneyExchangeUtils {
+    fun exchange(exchangeFrom: StdMoney, exchangeToCurrency: String): StdMoney {
+        val rateFrom = MoneyConfig.getRate(exchangeFrom.getMoneyCurrency())
+        val rateTo = MoneyConfig.getRate(exchangeToCurrency)
+        return Money(value = computeRate(rateFrom, rateTo, amountFrom = exchangeFrom.getMoneyValue()), currency = exchangeToCurrency)
+    }
+
+    private fun computeRate(rateFrom: Double, rateTo: Double, baseRate: Double = 1.0, amountFrom: Double = 1.0): Double {
+        return amountFrom * ((baseRate / rateFrom) / (baseRate / rateTo))
+    }
+}

src/main/kotlin/com/cubetiqs/libra/moneyutils/MoneyOperator.kt

@@ -1,7 +1,7 @@
 package com.cubetiqs.libra.moneyutils
 
-operator fun Money.unaryMinus() = (-value)
-operator fun Money.unaryPlus() = (+value)
+operator fun Money.unaryMinus() = (-getMoneyValue())
+operator fun Money.unaryPlus() = (+getMoneyValue())
 operator fun Money.inc() = Money(value++)
 operator fun Money.dec() = Money(value--)
 operator fun Money.plus(other: Money) = Money(value + other.value)

src/main/kotlin/com/cubetiqs/libra/moneyutils/StdMoney.kt

@@ -13,12 +13,12 @@ interface StdMoney {
      *
      * @return Double
      */
-    fun getValue(): Double
+    fun getMoneyValue(): Double
 
     /**
      * Get money's currency from current state.
      *
      * @return String
      */
-    fun getCurrency(): String
+    fun getMoneyCurrency(): String
 }

src/main/kotlin/com/cubetiqs/libra/moneyutils/StdMoneyFormation.kt

@@ -0,0 +1,6 @@
+package com.cubetiqs.libra.moneyutils
+
+interface StdMoneyFormation {
+    fun format(): String
+    fun toMoneyString(overrideSymbol: Char? = null): String
+}

src/test/kotlin/MoneyTests.kt

@@ -1,5 +1,6 @@
 import com.cubetiqs.libra.moneyutils.Money
 import com.cubetiqs.libra.moneyutils.MoneyConfig
+import com.cubetiqs.libra.moneyutils.MoneyExchangeUtils
 import com.cubetiqs.libra.moneyutils.plus
 import com.cubetiqs.libra.moneyutils.times
 import com.cubetiqs.libra.moneyutils.timesAssign
@@ -27,5 +28,10 @@ class MoneyTests {
             .parse("USD:1,KHR:4000")
 
         println(MoneyConfig.getConfig())
+
+        val moneyUsd = Money(10.0)
+        val moneyKhr = MoneyExchangeUtils.exchange(moneyUsd, "KHR")
+
+        Assert.assertEquals(40000.0, moneyKhr.getMoneyValue(), 0.0)
     }
 }