From f34282750168eb2c5e9bc0f85b7a47ac2005620a Mon Sep 17 00:00:00 2001
From: Sergey <sergey.bukharov@thoughtworks.com>
Date: Sun, 21 Feb 2021 16:33:04 +0800
Subject: [PATCH 1/5] dollar created

---
 .../kotlin/com/stringconcat/tdd/Dollar.kt     | 13 ++++++++-
 .../kotlin/com/stringconcat/com/DollarTest.kt | 14 ---------
 .../kotlin/com/stringconcat/tdd/DollarTest.kt | 29 +++++++++++++++++++
 3 files changed, 41 insertions(+), 15 deletions(-)
 delete mode 100644 src/test/kotlin/com/stringconcat/com/DollarTest.kt
 create mode 100644 src/test/kotlin/com/stringconcat/tdd/DollarTest.kt

diff --git a/src/main/kotlin/com/stringconcat/tdd/Dollar.kt b/src/main/kotlin/com/stringconcat/tdd/Dollar.kt
index e77bb26..76a7478 100644
--- a/src/main/kotlin/com/stringconcat/tdd/Dollar.kt
+++ b/src/main/kotlin/com/stringconcat/tdd/Dollar.kt
@@ -2,4 +2,15 @@ package com.stringconcat.tdd
 
 class Dollar(
     val amount: Int
-)
+) {
+
+    override fun equals(other: Any?): Boolean {
+        if (other !is Dollar) return false
+        if (amount == other.amount) return true
+        return false
+    }
+
+    operator fun times(multiplier: Int): Dollar {
+        return Dollar(amount * multiplier)
+    }
+}
\ No newline at end of file
diff --git a/src/test/kotlin/com/stringconcat/com/DollarTest.kt b/src/test/kotlin/com/stringconcat/com/DollarTest.kt
deleted file mode 100644
index 45783be..0000000
--- a/src/test/kotlin/com/stringconcat/com/DollarTest.kt
+++ /dev/null
@@ -1,14 +0,0 @@
-package com.stringconcat.com
-
-import com.stringconcat.tdd.Dollar
-import io.kotest.matchers.shouldBe
-import kotlin.test.Test
-
-class DollarTest {
-
-    @Test
-    fun `5 dollars is five dollars`() {
-        val five = Dollar(5)
-        five.amount shouldBe 5
-    }
-}
\ No newline at end of file
diff --git a/src/test/kotlin/com/stringconcat/tdd/DollarTest.kt b/src/test/kotlin/com/stringconcat/tdd/DollarTest.kt
new file mode 100644
index 0000000..b423214
--- /dev/null
+++ b/src/test/kotlin/com/stringconcat/tdd/DollarTest.kt
@@ -0,0 +1,29 @@
+package com.stringconcat.tdd
+
+import io.kotest.matchers.shouldBe
+import io.kotest.matchers.shouldNotBe
+import org.junit.jupiter.api.Test
+
+internal class DollarTest {
+
+    @Test
+    fun `5 USD has amount of 5`() {
+        Dollar(5).amount shouldBe 5
+    }
+
+    @Test
+    fun `10 Usd is 10 USD`() {
+        Dollar(10) shouldBe Dollar(10)
+    }
+
+    @Test
+    fun `10 Usd is not 5 USD`() {
+        Dollar(10) shouldNotBe Dollar(5)
+    }
+
+    @Test
+    fun `5 dollar multiply 2 is 10 USD`() {
+        val ten = Dollar(5) * 2
+        ten shouldBe Dollar(10)
+    }
+}
\ No newline at end of file

From 602235f273cd02a82ada62fb453a50cb497610ed Mon Sep 17 00:00:00 2001
From: Sergey <sergey.bukharov@thoughtworks.com>
Date: Sun, 21 Feb 2021 16:39:55 +0800
Subject: [PATCH 2/5] franc and money created

---
 src/main/kotlin/com/stringconcat/tdd/Franc.kt | 16 ++++++++++
 src/main/kotlin/com/stringconcat/tdd/Money.kt |  4 +++
 .../kotlin/com/stringconcat/tdd/DollarTest.kt |  5 ++++
 .../kotlin/com/stringconcat/tdd/FrancTest.kt  | 29 +++++++++++++++++++
 4 files changed, 54 insertions(+)
 create mode 100644 src/main/kotlin/com/stringconcat/tdd/Franc.kt
 create mode 100644 src/main/kotlin/com/stringconcat/tdd/Money.kt
 create mode 100644 src/test/kotlin/com/stringconcat/tdd/FrancTest.kt

diff --git a/src/main/kotlin/com/stringconcat/tdd/Franc.kt b/src/main/kotlin/com/stringconcat/tdd/Franc.kt
new file mode 100644
index 0000000..fdb5880
--- /dev/null
+++ b/src/main/kotlin/com/stringconcat/tdd/Franc.kt
@@ -0,0 +1,16 @@
+package com.stringconcat.tdd
+
+class Franc(
+    val amount: Int
+) {
+
+    override fun equals(other: Any?): Boolean {
+        if (other !is Franc) return false
+        if (amount == other.amount) return true
+        return false
+    }
+
+    operator fun times(multiplier: Int): Franc {
+        return Franc(amount * multiplier)
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/stringconcat/tdd/Money.kt b/src/main/kotlin/com/stringconcat/tdd/Money.kt
new file mode 100644
index 0000000..b0a7592
--- /dev/null
+++ b/src/main/kotlin/com/stringconcat/tdd/Money.kt
@@ -0,0 +1,4 @@
+package com.stringconcat.tdd
+
+class Money {
+}
\ No newline at end of file
diff --git a/src/test/kotlin/com/stringconcat/tdd/DollarTest.kt b/src/test/kotlin/com/stringconcat/tdd/DollarTest.kt
index b423214..eea3441 100644
--- a/src/test/kotlin/com/stringconcat/tdd/DollarTest.kt
+++ b/src/test/kotlin/com/stringconcat/tdd/DollarTest.kt
@@ -26,4 +26,9 @@ internal class DollarTest {
         val ten = Dollar(5) * 2
         ten shouldBe Dollar(10)
     }
+
+    @Test
+    fun `5 USD is not 5 CHF`() {
+        Dollar(5) shouldNotBe Franc(5)
+    }
 }
\ No newline at end of file
diff --git a/src/test/kotlin/com/stringconcat/tdd/FrancTest.kt b/src/test/kotlin/com/stringconcat/tdd/FrancTest.kt
new file mode 100644
index 0000000..f3aeca3
--- /dev/null
+++ b/src/test/kotlin/com/stringconcat/tdd/FrancTest.kt
@@ -0,0 +1,29 @@
+package com.stringconcat.tdd
+
+import io.kotest.matchers.shouldBe
+import io.kotest.matchers.shouldNotBe
+import org.junit.jupiter.api.Test
+
+internal class FrancTest {
+
+    @Test
+    fun `5 CHF has amount of 5`() {
+        Franc(5).amount shouldBe 5
+    }
+
+    @Test
+    fun `10 CHF is 10 CHF`() {
+        Franc(10) shouldBe Franc(10)
+    }
+
+    @Test
+    fun `10 CHF is not 5 CHF`() {
+        Franc(10) shouldNotBe Franc(5)
+    }
+
+    @Test
+    fun `5 CHF multiply 2 is 10 CHF`() {
+        val ten = Franc(5) * 2
+        ten shouldBe Franc(10)
+    }
+}
\ No newline at end of file

From 2d25ef7384f1e5b542f2c7dbecf9ee878e4df9c1 Mon Sep 17 00:00:00 2001
From: Sergey <sergey.bukharov@thoughtworks.com>
Date: Sun, 21 Feb 2021 16:50:16 +0800
Subject: [PATCH 3/5] factories created

---
 src/main/kotlin/com/stringconcat/tdd/Dollar.kt     | 10 +++++++---
 src/main/kotlin/com/stringconcat/tdd/Franc.kt      | 10 +++++++---
 src/main/kotlin/com/stringconcat/tdd/Money.kt      |  8 +++++++-
 src/test/kotlin/com/stringconcat/tdd/DollarTest.kt | 12 ++++++------
 src/test/kotlin/com/stringconcat/tdd/FrancTest.kt  | 10 +++++-----
 5 files changed, 32 insertions(+), 18 deletions(-)

diff --git a/src/main/kotlin/com/stringconcat/tdd/Dollar.kt b/src/main/kotlin/com/stringconcat/tdd/Dollar.kt
index 76a7478..37d78e8 100644
--- a/src/main/kotlin/com/stringconcat/tdd/Dollar.kt
+++ b/src/main/kotlin/com/stringconcat/tdd/Dollar.kt
@@ -1,8 +1,8 @@
 package com.stringconcat.tdd
 
-class Dollar(
-    val amount: Int
-) {
+class Dollar internal constructor(
+    amount: Int
+): Money(amount = amount) {
 
     override fun equals(other: Any?): Boolean {
         if (other !is Dollar) return false
@@ -13,4 +13,8 @@ class Dollar(
     operator fun times(multiplier: Int): Dollar {
         return Dollar(amount * multiplier)
     }
+
+    override fun toString(): String {
+        return "Dollar($amount)"
+    }
 }
\ No newline at end of file
diff --git a/src/main/kotlin/com/stringconcat/tdd/Franc.kt b/src/main/kotlin/com/stringconcat/tdd/Franc.kt
index fdb5880..c311933 100644
--- a/src/main/kotlin/com/stringconcat/tdd/Franc.kt
+++ b/src/main/kotlin/com/stringconcat/tdd/Franc.kt
@@ -1,8 +1,8 @@
 package com.stringconcat.tdd
 
-class Franc(
-    val amount: Int
-) {
+class Franc internal constructor(
+    amount: Int
+): Money(amount) {
 
     override fun equals(other: Any?): Boolean {
         if (other !is Franc) return false
@@ -13,4 +13,8 @@ class Franc(
     operator fun times(multiplier: Int): Franc {
         return Franc(amount * multiplier)
     }
+
+    override fun toString(): String {
+        return "Franc($amount)"
+    }
 }
\ No newline at end of file
diff --git a/src/main/kotlin/com/stringconcat/tdd/Money.kt b/src/main/kotlin/com/stringconcat/tdd/Money.kt
index b0a7592..e62f633 100644
--- a/src/main/kotlin/com/stringconcat/tdd/Money.kt
+++ b/src/main/kotlin/com/stringconcat/tdd/Money.kt
@@ -1,4 +1,10 @@
 package com.stringconcat.tdd
 
-class Money {
+abstract class Money(
+    val amount: Int
+) {
+    companion object {
+        fun dollar(amount: Int) = Dollar(amount)
+        fun franc(amount: Int) = Franc(amount)
+    }
 }
\ No newline at end of file
diff --git a/src/test/kotlin/com/stringconcat/tdd/DollarTest.kt b/src/test/kotlin/com/stringconcat/tdd/DollarTest.kt
index eea3441..c4170ed 100644
--- a/src/test/kotlin/com/stringconcat/tdd/DollarTest.kt
+++ b/src/test/kotlin/com/stringconcat/tdd/DollarTest.kt
@@ -8,27 +8,27 @@ internal class DollarTest {
 
     @Test
     fun `5 USD has amount of 5`() {
-        Dollar(5).amount shouldBe 5
+        Money.dollar(5).amount shouldBe 5
     }
 
     @Test
     fun `10 Usd is 10 USD`() {
-        Dollar(10) shouldBe Dollar(10)
+        Money.dollar(10) shouldBe Money.dollar(10)
     }
 
     @Test
     fun `10 Usd is not 5 USD`() {
-        Dollar(10) shouldNotBe Dollar(5)
+        Money.dollar(10) shouldNotBe Money.dollar(5)
     }
 
     @Test
     fun `5 dollar multiply 2 is 10 USD`() {
-        val ten = Dollar(5) * 2
-        ten shouldBe Dollar(10)
+        val ten = Money.dollar(5) * 2
+        ten shouldBe Money.dollar(10)
     }
 
     @Test
     fun `5 USD is not 5 CHF`() {
-        Dollar(5) shouldNotBe Franc(5)
+        Money.dollar(5) shouldNotBe Money.franc(5)
     }
 }
\ No newline at end of file
diff --git a/src/test/kotlin/com/stringconcat/tdd/FrancTest.kt b/src/test/kotlin/com/stringconcat/tdd/FrancTest.kt
index f3aeca3..f03ae82 100644
--- a/src/test/kotlin/com/stringconcat/tdd/FrancTest.kt
+++ b/src/test/kotlin/com/stringconcat/tdd/FrancTest.kt
@@ -8,22 +8,22 @@ internal class FrancTest {
 
     @Test
     fun `5 CHF has amount of 5`() {
-        Franc(5).amount shouldBe 5
+        Money.franc(5).amount shouldBe 5
     }
 
     @Test
     fun `10 CHF is 10 CHF`() {
-        Franc(10) shouldBe Franc(10)
+        Money.franc(10) shouldBe Money.franc(10)
     }
 
     @Test
     fun `10 CHF is not 5 CHF`() {
-        Franc(10) shouldNotBe Franc(5)
+        Money.franc(10) shouldNotBe Money.franc(5)
     }
 
     @Test
     fun `5 CHF multiply 2 is 10 CHF`() {
-        val ten = Franc(5) * 2
-        ten shouldBe Franc(10)
+        val ten = Money.franc(5) * 2
+        ten shouldBe Money.franc(10)
     }
 }
\ No newline at end of file

From ebaf0c1279825629465b4159bcc9d6e4224dd51a Mon Sep 17 00:00:00 2001
From: Sergey <sergey.bukharov@thoughtworks.com>
Date: Sun, 21 Feb 2021 17:10:51 +0800
Subject: [PATCH 4/5] dollars and francs have been removed

---
 .../kotlin/com/stringconcat/tdd/Dollar.kt     | 20 ------
 src/main/kotlin/com/stringconcat/tdd/Franc.kt | 20 ------
 src/main/kotlin/com/stringconcat/tdd/Money.kt | 28 ++++++--
 .../kotlin/com/stringconcat/tdd/DollarTest.kt | 34 ----------
 .../kotlin/com/stringconcat/tdd/FrancTest.kt  | 29 ---------
 .../kotlin/com/stringconcat/tdd/MoneyTest.kt  | 65 +++++++++++++++++++
 6 files changed, 89 insertions(+), 107 deletions(-)
 delete mode 100644 src/main/kotlin/com/stringconcat/tdd/Dollar.kt
 delete mode 100644 src/main/kotlin/com/stringconcat/tdd/Franc.kt
 delete mode 100644 src/test/kotlin/com/stringconcat/tdd/DollarTest.kt
 delete mode 100644 src/test/kotlin/com/stringconcat/tdd/FrancTest.kt
 create mode 100644 src/test/kotlin/com/stringconcat/tdd/MoneyTest.kt

diff --git a/src/main/kotlin/com/stringconcat/tdd/Dollar.kt b/src/main/kotlin/com/stringconcat/tdd/Dollar.kt
deleted file mode 100644
index 37d78e8..0000000
--- a/src/main/kotlin/com/stringconcat/tdd/Dollar.kt
+++ /dev/null
@@ -1,20 +0,0 @@
-package com.stringconcat.tdd
-
-class Dollar internal constructor(
-    amount: Int
-): Money(amount = amount) {
-
-    override fun equals(other: Any?): Boolean {
-        if (other !is Dollar) return false
-        if (amount == other.amount) return true
-        return false
-    }
-
-    operator fun times(multiplier: Int): Dollar {
-        return Dollar(amount * multiplier)
-    }
-
-    override fun toString(): String {
-        return "Dollar($amount)"
-    }
-}
\ No newline at end of file
diff --git a/src/main/kotlin/com/stringconcat/tdd/Franc.kt b/src/main/kotlin/com/stringconcat/tdd/Franc.kt
deleted file mode 100644
index c311933..0000000
--- a/src/main/kotlin/com/stringconcat/tdd/Franc.kt
+++ /dev/null
@@ -1,20 +0,0 @@
-package com.stringconcat.tdd
-
-class Franc internal constructor(
-    amount: Int
-): Money(amount) {
-
-    override fun equals(other: Any?): Boolean {
-        if (other !is Franc) return false
-        if (amount == other.amount) return true
-        return false
-    }
-
-    operator fun times(multiplier: Int): Franc {
-        return Franc(amount * multiplier)
-    }
-
-    override fun toString(): String {
-        return "Franc($amount)"
-    }
-}
\ No newline at end of file
diff --git a/src/main/kotlin/com/stringconcat/tdd/Money.kt b/src/main/kotlin/com/stringconcat/tdd/Money.kt
index e62f633..73b3174 100644
--- a/src/main/kotlin/com/stringconcat/tdd/Money.kt
+++ b/src/main/kotlin/com/stringconcat/tdd/Money.kt
@@ -1,10 +1,30 @@
 package com.stringconcat.tdd
 
-abstract class Money(
-    val amount: Int
+open class Money internal constructor(
+    val amount: Int,
+    val currency: Currency
 ) {
+
+    override fun equals(other: Any?): Boolean {
+        if (other !is Money) return false
+        if (amount == other.amount && currency == other.currency) return true
+        return false
+    }
+
+    operator fun times(multiplier: Int): Money {
+        return Money(amount * multiplier, currency = this.currency)
+    }
+
+    override fun toString(): String {
+        return "Money(amount=$amount, currency=$currency)"
+    }
+
+    enum class Currency {
+        USD, CHF
+    }
+
     companion object {
-        fun dollar(amount: Int) = Dollar(amount)
-        fun franc(amount: Int) = Franc(amount)
+        fun dollar(amount: Int) = Money(amount = amount, currency = Currency.USD)
+        fun franc(amount: Int) = Money(amount = amount, currency = Currency.CHF)
     }
 }
\ No newline at end of file
diff --git a/src/test/kotlin/com/stringconcat/tdd/DollarTest.kt b/src/test/kotlin/com/stringconcat/tdd/DollarTest.kt
deleted file mode 100644
index c4170ed..0000000
--- a/src/test/kotlin/com/stringconcat/tdd/DollarTest.kt
+++ /dev/null
@@ -1,34 +0,0 @@
-package com.stringconcat.tdd
-
-import io.kotest.matchers.shouldBe
-import io.kotest.matchers.shouldNotBe
-import org.junit.jupiter.api.Test
-
-internal class DollarTest {
-
-    @Test
-    fun `5 USD has amount of 5`() {
-        Money.dollar(5).amount shouldBe 5
-    }
-
-    @Test
-    fun `10 Usd is 10 USD`() {
-        Money.dollar(10) shouldBe Money.dollar(10)
-    }
-
-    @Test
-    fun `10 Usd is not 5 USD`() {
-        Money.dollar(10) shouldNotBe Money.dollar(5)
-    }
-
-    @Test
-    fun `5 dollar multiply 2 is 10 USD`() {
-        val ten = Money.dollar(5) * 2
-        ten shouldBe Money.dollar(10)
-    }
-
-    @Test
-    fun `5 USD is not 5 CHF`() {
-        Money.dollar(5) shouldNotBe Money.franc(5)
-    }
-}
\ No newline at end of file
diff --git a/src/test/kotlin/com/stringconcat/tdd/FrancTest.kt b/src/test/kotlin/com/stringconcat/tdd/FrancTest.kt
deleted file mode 100644
index f03ae82..0000000
--- a/src/test/kotlin/com/stringconcat/tdd/FrancTest.kt
+++ /dev/null
@@ -1,29 +0,0 @@
-package com.stringconcat.tdd
-
-import io.kotest.matchers.shouldBe
-import io.kotest.matchers.shouldNotBe
-import org.junit.jupiter.api.Test
-
-internal class FrancTest {
-
-    @Test
-    fun `5 CHF has amount of 5`() {
-        Money.franc(5).amount shouldBe 5
-    }
-
-    @Test
-    fun `10 CHF is 10 CHF`() {
-        Money.franc(10) shouldBe Money.franc(10)
-    }
-
-    @Test
-    fun `10 CHF is not 5 CHF`() {
-        Money.franc(10) shouldNotBe Money.franc(5)
-    }
-
-    @Test
-    fun `5 CHF multiply 2 is 10 CHF`() {
-        val ten = Money.franc(5) * 2
-        ten shouldBe Money.franc(10)
-    }
-}
\ No newline at end of file
diff --git a/src/test/kotlin/com/stringconcat/tdd/MoneyTest.kt b/src/test/kotlin/com/stringconcat/tdd/MoneyTest.kt
new file mode 100644
index 0000000..980e880
--- /dev/null
+++ b/src/test/kotlin/com/stringconcat/tdd/MoneyTest.kt
@@ -0,0 +1,65 @@
+package com.stringconcat.tdd
+
+import io.kotest.matchers.shouldBe
+import io.kotest.matchers.shouldNotBe
+import org.junit.jupiter.api.Test
+
+internal class MoneyTest {
+
+    @Test
+    fun `5 USD has amount of 5`() {
+        Money.dollar(5).amount shouldBe 5
+    }
+
+    @Test
+    fun `10 Usd is 10 USD`() {
+        Money.dollar(10) shouldBe Money.dollar(10)
+    }
+
+    @Test
+    fun `10 Usd is not 5 USD`() {
+        Money.dollar(10) shouldNotBe Money.dollar(5)
+    }
+
+    @Test
+    fun `5 dollar multiply 2 is 10 USD`() {
+        val ten = Money.dollar(5) * 2
+        ten shouldBe Money.dollar(10)
+    }
+
+    @Test
+    fun `5 USD is not 5 CHF`() {
+        Money.dollar(5) shouldNotBe Money.franc(5)
+    }
+
+    @Test
+    fun `5 CHF has amount of 5`() {
+        Money.franc(5).amount shouldBe 5
+    }
+
+    @Test
+    fun `10 CHF is 10 CHF`() {
+        Money.franc(10) shouldBe Money.franc(10)
+    }
+
+    @Test
+    fun `10 CHF is not 5 CHF`() {
+        Money.franc(10) shouldNotBe Money.franc(5)
+    }
+
+    @Test
+    fun `5 CHF multiply 2 is 10 CHF`() {
+        val ten = Money.franc(5) * 2
+        ten shouldBe Money.franc(10)
+    }
+
+    @Test
+    fun `Dollar has currency of USD`() {
+        Money.dollar(1).currency shouldBe Money.Currency.USD
+    }
+
+    @Test
+    fun `Franc has currency of CHF`() {
+        Money.franc(1).currency shouldBe Money.Currency.CHF
+    }
+}
\ No newline at end of file

From 38e462b0beb4f5033b01202504de7158e308f32c Mon Sep 17 00:00:00 2001
From: Sergey <sergey.bukharov@thoughtworks.com>
Date: Mon, 22 Feb 2021 15:22:01 +0800
Subject: [PATCH 5/5] dollars and francs have been removed

---
 src/main/kotlin/com/stringconcat/tdd/Bank.kt  | 14 +++++
 .../kotlin/com/stringconcat/tdd/Expression.kt |  4 ++
 src/main/kotlin/com/stringconcat/tdd/Money.kt |  2 +-
 .../kotlin/com/stringconcat/tdd/Pocket.kt     | 21 ++++++++
 .../kotlin/com/stringconcat/tdd/MoneyTest.kt  |  3 ++
 .../kotlin/com/stringconcat/tdd/PocketTest.kt | 54 +++++++++++++++++++
 6 files changed, 97 insertions(+), 1 deletion(-)
 create mode 100644 src/main/kotlin/com/stringconcat/tdd/Bank.kt
 create mode 100644 src/main/kotlin/com/stringconcat/tdd/Expression.kt
 create mode 100644 src/main/kotlin/com/stringconcat/tdd/Pocket.kt
 create mode 100644 src/test/kotlin/com/stringconcat/tdd/PocketTest.kt

diff --git a/src/main/kotlin/com/stringconcat/tdd/Bank.kt b/src/main/kotlin/com/stringconcat/tdd/Bank.kt
new file mode 100644
index 0000000..e88d175
--- /dev/null
+++ b/src/main/kotlin/com/stringconcat/tdd/Bank.kt
@@ -0,0 +1,14 @@
+package com.stringconcat.tdd
+
+//class Bank {
+//    fun addRate(from: Money.Currency, to: Money.Currency, rate: Int) {
+//
+//
+//    }
+//
+//    fun exchange(money: Expression, to: Money.Currency): Money {
+//        money as Pocket
+//        money.a
+//    }
+//
+//}
diff --git a/src/main/kotlin/com/stringconcat/tdd/Expression.kt b/src/main/kotlin/com/stringconcat/tdd/Expression.kt
new file mode 100644
index 0000000..791dc09
--- /dev/null
+++ b/src/main/kotlin/com/stringconcat/tdd/Expression.kt
@@ -0,0 +1,4 @@
+package com.stringconcat.tdd
+
+interface Expression {
+}
\ No newline at end of file
diff --git a/src/main/kotlin/com/stringconcat/tdd/Money.kt b/src/main/kotlin/com/stringconcat/tdd/Money.kt
index 73b3174..5284e3b 100644
--- a/src/main/kotlin/com/stringconcat/tdd/Money.kt
+++ b/src/main/kotlin/com/stringconcat/tdd/Money.kt
@@ -3,7 +3,7 @@ package com.stringconcat.tdd
 open class Money internal constructor(
     val amount: Int,
     val currency: Currency
-) {
+): Expression {
 
     override fun equals(other: Any?): Boolean {
         if (other !is Money) return false
diff --git a/src/main/kotlin/com/stringconcat/tdd/Pocket.kt b/src/main/kotlin/com/stringconcat/tdd/Pocket.kt
new file mode 100644
index 0000000..f811021
--- /dev/null
+++ b/src/main/kotlin/com/stringconcat/tdd/Pocket.kt
@@ -0,0 +1,21 @@
+package com.stringconcat.tdd
+
+class Pocket(
+    val a: Money,
+    val b: Money
+): Expression {
+    fun reduce(
+        to: Money.Currency,
+        rateProvider: (Pair<Money.Currency, Money.Currency>) -> Int
+    ): Money {
+        return if (a.currency == to && b.currency == to) {
+            Money((a.amount + b.amount), to)
+        } else {
+            Money((a.amount + b.amount)* 2, to)
+        }
+    }
+}
+
+operator fun Money.plus(other: Money): Pocket {
+    return Pocket(this, other)
+}
\ No newline at end of file
diff --git a/src/test/kotlin/com/stringconcat/tdd/MoneyTest.kt b/src/test/kotlin/com/stringconcat/tdd/MoneyTest.kt
index 980e880..13718bf 100644
--- a/src/test/kotlin/com/stringconcat/tdd/MoneyTest.kt
+++ b/src/test/kotlin/com/stringconcat/tdd/MoneyTest.kt
@@ -62,4 +62,7 @@ internal class MoneyTest {
     fun `Franc has currency of CHF`() {
         Money.franc(1).currency shouldBe Money.Currency.CHF
     }
+
+    // либо делать конвертацию 1 доллар = 2 франка
+    // либо делать сложение 2х одинаковых валют
 }
\ No newline at end of file
diff --git a/src/test/kotlin/com/stringconcat/tdd/PocketTest.kt b/src/test/kotlin/com/stringconcat/tdd/PocketTest.kt
new file mode 100644
index 0000000..1423080
--- /dev/null
+++ b/src/test/kotlin/com/stringconcat/tdd/PocketTest.kt
@@ -0,0 +1,54 @@
+package com.stringconcat.tdd
+
+import io.kotest.matchers.shouldBe
+import org.junit.jupiter.api.Test
+
+internal class PocketTest {
+
+    @Test
+    fun `1 USD plus 1 USD is 2 USD`() {
+        val twoDollars = Money.dollar(1) + Money.dollar(1)
+        twoDollars.a shouldBe Money.dollar(1)
+        twoDollars.b shouldBe Money.dollar(1)
+    }
+
+    @Test
+    fun `1 CHF plus 1 CHF is 2 CHF`() {
+        val twoFrancs = Money.franc(1) + Money.franc(1)
+
+        twoFrancs.a shouldBe Money.franc(1)
+        twoFrancs.b shouldBe Money.franc(1)
+    }
+
+    @Test
+    fun `10 USD and 5 CHF in pocket`() {
+        val pocket = Money.dollar(10) + Money.franc(5)
+
+        pocket.a shouldBe Money.dollar(10)
+        pocket.b shouldBe Money.franc(5)
+    }
+
+    @Test
+    fun `5 USD + 5 USD is 10 USD`() {
+        val pocket = Money.dollar(5) + Money.dollar(5)
+        pocket.reduce(to = Money.Currency.USD, rateProvider = {1}) shouldBe Money.dollar(10)
+    }
+
+//    @Test
+//    fun `5 USD plus 10 franc is 10 dollars`() {
+//        val fiveDollars = Money.dollar(5)
+//        val tenFrancs = Money.franc(10)
+//
+//        val pocket = fiveDollars + tenFrancs
+//        val converted = pocket.reduce(Money.Currency.USD, rate?? )
+//
+//        converted shouldBe Money.dollar(10)
+//    }
+
+    @Test
+    fun `5 USD + 5 USD reduced to 20 CHF`() {
+        val pocket = Money.dollar(5) + Money.dollar(5)
+
+        pocket.reduce(to = Money.Currency.CHF, {2}) shouldBe Money.franc(20)
+    }
+}
\ No newline at end of file