From 8a0c57598e83a2e9361c51ef6dce6045c1c26798 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tobias=20Sch=C3=BCrg?= <tobiasschuerg@gmail.com>
Date: Sun, 30 Aug 2020 16:42:08 +0200
Subject: [PATCH] Enabled additon and substraction with Zero money.

---
 money/build.gradle                            |  4 ++--
 .../main/java/de/tobiasschuerg/money/Money.kt | 21 ++++++++++++-------
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/money/build.gradle b/money/build.gradle
index 923065a..6fd9e0d 100644
--- a/money/build.gradle
+++ b/money/build.gradle
@@ -9,8 +9,8 @@ android {
 
     defaultConfig {
         minSdkVersion 14
-        versionCode 9
-        versionName "0.9.0"
+        versionCode 10
+        versionName "0.9.1"
 
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
 
diff --git a/money/src/main/java/de/tobiasschuerg/money/Money.kt b/money/src/main/java/de/tobiasschuerg/money/Money.kt
index eec5e23..36a0113 100644
--- a/money/src/main/java/de/tobiasschuerg/money/Money.kt
+++ b/money/src/main/java/de/tobiasschuerg/money/Money.kt
@@ -15,10 +15,14 @@ data class Money(val amount: BigDecimal = BigDecimal.ZERO, val currency: Currenc
     constructor(amount: Double, currency: Currency) : this(BigDecimal(amount), currency)
     constructor(amount: Long, currency: Currency) : this(BigDecimal(amount), currency)
 
-    operator fun plus(money: Money): Money {
-        requireSameCurrency(money)
-        val sum = amount.add(money.amount)
-        return Money(sum, currency)
+    operator fun plus(money: Money): Money = when {
+        this.isZero() -> money
+        money.isZero() -> this
+        else -> {
+            requireSameCurrency(money)
+            val sum = amount.add(money.amount)
+            Money(sum, currency)
+        }
     }
 
     override operator fun compareTo(other: Money): Int {
@@ -59,9 +63,12 @@ data class Money(val amount: BigDecimal = BigDecimal.ZERO, val currency: Currenc
     }
 
     operator fun minus(money: Money): Money {
-        requireSameCurrency(money)
-        val result = amount.subtract(money.amount)
-        return Money(result, currency)
+        return if (money.isZero()) this
+        else {
+            requireSameCurrency(money)
+            val result = amount.subtract(money.amount)
+            Money(result, currency)
+        }
     }
 
     private fun requireSameCurrency(money: Money) {