Add test case for BinaryToDecimal (#3684)

src/main/java/com/thealgorithms/conversions/BinaryToDecimal.java

@@ -7,6 +7,17 @@ import java.util.Scanner;
  */
 class BinaryToDecimal {
 
+    public static int binaryToDecimal(int binNum) {
+        int binCopy, d, s = 0, power = 0;
+        binCopy = binNum;
+        while (binCopy != 0) {
+            d = binCopy % 10;
+            s += d * (int) Math.pow(2, power++);
+            binCopy /= 10;
+        }
+        return s;
+    }
+
     /**
      * Main Method
      *
@@ -14,16 +25,8 @@ class BinaryToDecimal {
      */
     public static void main(String args[]) {
         Scanner sc = new Scanner(System.in);
-        int binNum, binCopy, d, s = 0, power = 0;
         System.out.print("Binary number: ");
-        binNum = sc.nextInt();
+        System.out.println("Decimal equivalent:" + binaryToDecimal(sc.nextInt()));
-        binCopy = binNum;
-        while (binCopy != 0) {
-            d = binCopy % 10;
-            s += d * (int) Math.pow(2, power++);
-            binCopy /= 10;
-        }
-        System.out.println("Decimal equivalent:" + s);
         sc.close();
     }
 }

src/test/java/com/thealgorithms/conversions/BinaryToDecimalTest.java

@@ -0,0 +1,18 @@
+package com.thealgorithms.conversions;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class BinaryToDecimalTest {
+
+    @Test
+    public void testBinaryToDecimal() {
+        //zeros at the starting should be removed
+        assertEquals(0, BinaryToDecimal.binaryToDecimal(0));
+        assertEquals(1, BinaryToDecimal.binaryToDecimal(1));
+        assertEquals(5, BinaryToDecimal.binaryToDecimal(101));
+        assertEquals(63, BinaryToDecimal.binaryToDecimal(111111));
+        assertEquals(512, BinaryToDecimal.binaryToDecimal(1000000000));
+    }
+}