Added more tests in MinimumBinaryFlips with some modifications

src/main/java/com/shortthirdman/quickstart/leetcode/MinimumBinaryFlips.java

@@ -1,5 +1,7 @@
 package com.shortthirdman.quickstart.leetcode;
 
+import java.util.Objects;
+
 /**
  * A password string, pwd, consists of binary characters (0s and 1s). A cyber-security expert is trying to determine the
  * minimum number of changes required to make the password secure.
@@ -18,9 +20,13 @@ public class MinimumBinaryFlips {
 	 * @param text the binary string
 	 * @return the minimum number of flips to make the division possible 
 	 */
-	public Integer getMinFlips(String text) {
+	public int getMinFlips(String text) {
 		int minFlips = Integer.MAX_VALUE;
 
+        if (Objects.isNull(text)) {
+            throw new NullPointerException("Input text password can not be null");
+        }
+
         int len = text.length();
 
         int flipsToMakeAllZeros = flipsToMakeAllSame(text, '0');
@@ -41,11 +47,11 @@ public Integer getMinFlips(String text) {
             minFlips = Math.min(minFlips, Math.min(flipsToZeroPart1 + flipsToOnePart2, flipsToOnePart1 + flipsToZeroPart2));
         }
 
-        return Integer.valueOf(minFlips);
+        return minFlips;
 	}
 
 
-	public int flipsToMakeAllSame(String str, char targetChar) {
+	private int flipsToMakeAllSame(String str, char targetChar) {
         int flips = 0;
         for (char c : str.toCharArray()) {
             if (c != targetChar) {

src/test/java/com/shortthirdman/quickstart/leetcode/MinimumBinaryFlipsTest.java

@@ -1,10 +1,10 @@
 package com.shortthirdman.quickstart.leetcode;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
+import static org.junit.jupiter.api.Assertions.*;
+
 public class MinimumBinaryFlipsTest {
 
 	MinimumBinaryFlips app;
@@ -24,4 +24,85 @@ public void testGetMinFlips_defaultScenario() {
         assertEquals(2, app.getMinFlips(secondPwd));
         assertEquals(3, app.getMinFlips(thirdPwd));
 	}
+
+	// Positive Test Cases
+	@Test
+	void testAllZeros() {
+		assertEquals(0, app.getMinFlips("0000"));
+	}
+
+	@Test
+	void testAllOnes() {
+		assertEquals(0, app.getMinFlips("1111"));
+	}
+
+	@Test
+	void testAlternatingCharacters() {
+		assertEquals(3, app.getMinFlips("010101"));
+		assertNotEquals(2, app.getMinFlips("010101"));
+	}
+
+	@Test
+	void testMixedCharacters() {
+		assertEquals(0, app.getMinFlips("1100"));
+		assertNotEquals(1, app.getMinFlips("1100"));
+	}
+
+	@Test
+	void testShortString() {
+		assertEquals(0, app.getMinFlips("1")); // Edge case with a single character
+	}
+
+	@Test
+	void testTwoDifferentChars() {
+		assertEquals(1, app.getMinFlips("01"));
+	}
+
+	// Negative Test Cases
+	@Test
+	void testEmptyString() {
+		assertEquals(0, app.getMinFlips(""));
+	}
+
+	@Test
+	void testSingleCharacterZero() {
+		assertEquals(0, app.getMinFlips("0"));
+	}
+
+	@Test
+	void testSingleCharacterOne() {
+		assertEquals(0, app.getMinFlips("1"));
+	}
+
+	@Test
+	void testTwoSameChars() {
+		assertEquals(0, app.getMinFlips("00")); // Both are zeros
+		assertEquals(0, app.getMinFlips("11")); // Both are ones
+	}
+
+	// Edge Cases
+	@Test
+	void testLargeInput() {
+		StringBuilder largeInput = new StringBuilder();
+		for (int i = 0; i < 10000; i++) {
+			largeInput.append(i % 2 == 0 ? '0' : '1');
+		}
+		assertEquals(5000, app.getMinFlips(largeInput.toString()));
+	}
+
+	@Test
+	void testLongSameChars() {
+		String longZeros = "0".repeat(10000);
+		assertEquals(0, app.getMinFlips(longZeros));
+
+		String longOnes = "1".repeat(10000);
+		assertEquals(0, app.getMinFlips(longOnes));
+	}
+
+	// Exception Handling Test Cases
+	@Test
+	void testNullInput() {
+		Exception exception = assertThrows(NullPointerException.class, () -> app.getMinFlips(null));
+		assertEquals("Input text password can not be null", exception.getMessage());
+	}
 }