Add test case to Binomial Coefficient Algorithm (#3179)

Co-authored-by: Yang Libin <contact@yanglibin.info>

src/main/java/com/thealgorithms/maths/BinomialCoefficient.java

@@ -15,32 +15,25 @@ public class BinomialCoefficient {
     /**
      * This method returns the number of ways in which k objects can be chosen from n objects
      *
-     * @param total_objects Total number of objects
+     * @param totalObjects    Total number of objects
-     * @param no_of_objects Number of objects to be chosen from total_objects
+     * @param numberOfObjects Number of objects to be chosen from total_objects
      * @return number of ways in which no_of_objects objects can be chosen from total_objects objects
      */
 
-	static int binomialCoefficient(int total_objects, int no_of_objects) {
+    public static int binomialCoefficient(int totalObjects, int numberOfObjects) {
 
-		//Base Case
+        // Base Case
-		if(no_of_objects > total_objects) {
+        if (numberOfObjects > totalObjects) {
             return 0;
         }
 
-		//Base Case
+        // Base Case
-		if(no_of_objects == 0 || no_of_objects == total_objects) {
+        if (numberOfObjects == 0 || numberOfObjects == totalObjects) {
             return 1;
         }
 
-		//Recursive Call
+        // Recursive Call
-		return binomialCoefficient(total_objects - 1, no_of_objects - 1)
+        return binomialCoefficient(totalObjects - 1, numberOfObjects - 1)
-				+ binomialCoefficient(total_objects - 1, no_of_objects);
+                + binomialCoefficient(totalObjects - 1, numberOfObjects);
     }
-	
-	public static void main(String[] args) {
-		System.out.println(binomialCoefficient(20,2));
-		
-		//Output: 190
-	}
-
 }

src/test/java/com/thealgorithms/maths/BinomialCoefficientTest.java

@@ -0,0 +1,18 @@
+package com.thealgorithms.maths;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class BinomialCoefficientTest {
+
+    @Test
+    void testBinomialCoefficient() {
+
+        assertEquals(190, BinomialCoefficient.binomialCoefficient(20, 2));
+        assertEquals(792, BinomialCoefficient.binomialCoefficient(12, 5));
+        assertEquals(84, BinomialCoefficient.binomialCoefficient(9, 3));
+        assertEquals(1, BinomialCoefficient.binomialCoefficient(17, 17));
+
+    }
+}