This commit related to the article BAEL-6877 (#14676)

This commit aims to add a new test class to convert a HashMap string into a HashMap object using toString().

core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/UsingtoStringUnitTest.java

@@ -0,0 +1,42 @@
+package com.baeldung.map;
+
+import org.junit.Test;
+
+import java.util.HashMap;
+
+import static org.junit.Assert.assertEquals;
+
+public class UsingtoStringUnitTest {
+
+    @Test
+    public void given_HashMapString_whenUsingtoString_thenConvertToHashMapObject() {
+        // Example string representation of a HashMap
+        String hashMapString = "{key1=value1, key2=value2, key3=value3}";
+
+        // Remove unnecessary characters
+        String keyValuePairs = hashMapString.replaceAll("[{}\\s]", "");
+
+        // Split into individual key-value pairs
+        String[] pairs = keyValuePairs.split(",");
+
+        // Create a new HashMap
+        HashMap<String, String> expectedHashMap = new HashMap<>();
+        expectedHashMap.put("key1", "value1");
+        expectedHashMap.put("key2", "value2");
+        expectedHashMap.put("key3", "value3");
+
+        HashMap<String, String> actualHashMap = new HashMap<>();
+
+        // Parse and populate the HashMap
+        for (String pair : pairs) {
+            String[] keyValue = pair.split("=");
+            if (keyValue.length == 2) {
+                actualHashMap.put(keyValue[0], keyValue[1]);
+            }
+        }
+
+        // Assert that the converted HashMap matches the expected one
+        assertEquals(expectedHashMap, actualHashMap);
+    }
+
+}