From 6ddb26f48d79b983a3f8f2509fae4c67aef612f7 Mon Sep 17 00:00:00 2001
From: Hardik Pawar <97388607+Hardvan@users.noreply.github.com>
Date: Thu, 10 Oct 2024 00:34:04 +0530
Subject: [PATCH] Add tests, remove `main` & `print` methods in
 `CoinChange.java` (#5642)

---
 DIRECTORY.md                                  |  1 +
 .../dynamicprogramming/CoinChange.java        | 22 +----
 .../dynamicprogramming/CoinChangeTest.java    | 80 +++++++++++++++++++
 3 files changed, 82 insertions(+), 21 deletions(-)
 create mode 100644 src/test/java/com/thealgorithms/dynamicprogramming/CoinChangeTest.java

diff --git a/DIRECTORY.md b/DIRECTORY.md
index 70de110e8..0c235b792 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -786,6 +786,7 @@
             * [BruteForceKnapsackTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/dynamicprogramming/BruteForceKnapsackTest.java)
             * [CatalanNumberTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/dynamicprogramming/CatalanNumberTest.java)
             * [ClimbStairsTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/dynamicprogramming/ClimbStairsTest.java)
+            * [CoinChangeTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/dynamicprogramming/CoinChangeTest.java)
             * [CountFriendsPairingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/dynamicprogramming/CountFriendsPairingTest.java)
             * [EditDistanceTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/dynamicprogramming/EditDistanceTest.java)
             * [EggDroppingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/dynamicprogramming/EggDroppingTest.java)
diff --git a/src/main/java/com/thealgorithms/dynamicprogramming/CoinChange.java b/src/main/java/com/thealgorithms/dynamicprogramming/CoinChange.java
index 12cc29faa..7edc9603d 100644
--- a/src/main/java/com/thealgorithms/dynamicprogramming/CoinChange.java
+++ b/src/main/java/com/thealgorithms/dynamicprogramming/CoinChange.java
@@ -7,15 +7,6 @@ public final class CoinChange {
     private CoinChange() {
     }
 
-    // Driver Program
-    public static void main(String[] args) {
-        int amount = 12;
-        int[] coins = {2, 4, 5};
-
-        System.out.println("Number of combinations of getting change for " + amount + " is: " + change(coins, amount));
-        System.out.println("Minimum number of coins required for amount :" + amount + " is: " + minimumCoins(coins, amount));
-    }
-
     /**
      * This method finds the number of combinations of getting change for a
      * given amount and change coins
@@ -32,8 +23,6 @@ public final class CoinChange {
             for (int i = coin; i < amount + 1; i++) {
                 combinations[i] += combinations[i - coin];
             }
-            // Uncomment the below line to see the state of combinations for each coin
-            // printAmount(combinations);
         }
 
         return combinations[amount];
@@ -65,16 +54,7 @@ public final class CoinChange {
                 }
             }
         }
-        // Uncomment the below line to see the state of combinations for each coin
-        // printAmount(minimumCoins);
+
         return minimumCoins[amount];
     }
-
-    // A basic print method which prints all the contents of the array
-    public static void printAmount(int[] arr) {
-        for (int i = 0; i < arr.length; i++) {
-            System.out.print(arr[i] + " ");
-        }
-        System.out.println();
-    }
 }
diff --git a/src/test/java/com/thealgorithms/dynamicprogramming/CoinChangeTest.java b/src/test/java/com/thealgorithms/dynamicprogramming/CoinChangeTest.java
new file mode 100644
index 000000000..10bc6600a
--- /dev/null
+++ b/src/test/java/com/thealgorithms/dynamicprogramming/CoinChangeTest.java
@@ -0,0 +1,80 @@
+package com.thealgorithms.dynamicprogramming;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class CoinChangeTest {
+
+    @Test
+    void testChangeBasic() {
+        int amount = 12;
+        int[] coins = {2, 4, 5};
+
+        assertEquals(5, CoinChange.change(coins, amount));
+    }
+
+    @Test
+    void testChangeNoCoins() {
+        int amount = 12;
+        int[] coins = {};
+
+        assertEquals(0, CoinChange.change(coins, amount));
+    }
+
+    @Test
+    void testChangeNoAmount() {
+        int amount = 0;
+        int[] coins = {2, 4, 5};
+
+        assertEquals(1, CoinChange.change(coins, amount));
+    }
+
+    @Test
+    void testChangeImpossibleAmount() {
+        int amount = 3;
+        int[] coins = {2, 4, 5};
+
+        assertEquals(0, CoinChange.change(coins, amount));
+    }
+
+    @Test
+    void testMinimumCoinsBasic() {
+        int amount = 12;
+        int[] coins = {2, 4, 5};
+
+        assertEquals(3, CoinChange.minimumCoins(coins, amount));
+    }
+
+    @Test
+    void testMinimumCoinsNoCoins() {
+        int amount = 12;
+        int[] coins = {};
+
+        assertEquals(Integer.MAX_VALUE, CoinChange.minimumCoins(coins, amount));
+    }
+
+    @Test
+    void testMinimumCoinsNoAmount() {
+        int amount = 0;
+        int[] coins = {2, 4, 5};
+
+        assertEquals(0, CoinChange.minimumCoins(coins, amount));
+    }
+
+    @Test
+    void testMinimumCoinsImpossibleAmount() {
+        int amount = 3;
+        int[] coins = {2, 4, 5};
+
+        assertEquals(Integer.MAX_VALUE, CoinChange.minimumCoins(coins, amount));
+    }
+
+    @Test
+    void testMinimumCoinsExactAmount() {
+        int amount = 10;
+        int[] coins = {1, 5, 10};
+
+        assertEquals(1, CoinChange.minimumCoins(coins, amount));
+    }
+}