Some refactoring and added Unit Test for Struct

Author: akuzin1

src/main/java/org/opensearch/jdbc/StructImpl.java

@@ -8,6 +8,7 @@
 
 import java.sql.SQLException;
 import java.sql.Struct;
+import java.util.Arrays;
 import java.util.Map;
 
 public class StructImpl implements Struct{
@@ -30,4 +31,24 @@ public Object[] getAttributes() throws SQLException {
     public Object[] getAttributes(Map<String,Class<?>> map) throws SQLException {
         throw new java.lang.UnsupportedOperationException("Not supported yet.");
     }
+
+    public boolean equals(Object obj) {
+        if (!(obj instanceof Struct)) {
+            return false;
+        }
+        if (obj == this) {
+            return true;
+        }
+        Struct other = (Struct) obj;
+        try {
+            if (!typeName.equals(other.getSQLTypeName())) {
+                return false;
+            }
+            Object[] otherAttributes = other.getAttributes();
+            return Arrays.equals(attributes, otherAttributes);
+        }
+        catch (Exception e) {
+            return false;
+        }
+    }
 }

src/main/java/org/opensearch/jdbc/types/StructType.java

@@ -30,13 +30,7 @@ public String getTypeName() {
 
     @Override
     public Struct fromValue(Object value, Map<String, Object> conversionParams) {
-        int i = 0;
         Map<String, Object> structKeyValues = (Map<String, Object>) value;
-        Object[] attributes = new Map.Entry[structKeyValues.size()];
-
-        for(Map.Entry<String, Object> entry: structKeyValues.entrySet()) {
-            attributes[i++] = entry;
-        }
-        return new StructImpl(getTypeName(), attributes);
+        return new StructImpl(getTypeName(), structKeyValues.entrySet().toArray());
     }
  }

src/main/java/org/opensearch/jdbc/types/TypeConverters.java

@@ -68,10 +68,7 @@ public static TypeConverter getInstance(JDBCType jdbcType) {
 
     public static class StructTypeConverter extends BaseTypeConverter {
 
-        private static final Set<Class> supportedJavaClasses = Collections.unmodifiableSet(
-                new HashSet<>(Arrays.asList(
-                        Struct.class
-                )));
+        private static final Set<Class> supportedJavaClasses = Collections.singleton(Struct.class);
 
         StructTypeConverter() {
 

src/test/java/org/opensearch/jdbc/types/StructTypeTests.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+
+ package org.opensearch.jdbc.types;
+ 
+ import static org.junit.jupiter.api.Assertions.*;
+ import org.junit.jupiter.api.Test;
+ import org.opensearch.jdbc.types.StructType;
+ import org.opensearch.jdbc.StructImpl;
+
+ import java.sql.Struct;
+ import java.sql.SQLException;
+ import java.util.Arrays;
+ import java.util.Map;
+ import java.util.HashMap;
+ 
+ public class StructTypeTests {
+
+    @Test
+    public void testStructTypeFromValue() throws SQLException {
+        Map<String, Object> attributes = new HashMap<String, Object>() {{
+            put("attribute1", "value1");
+            put("attribute2", 2);
+            put("attribute3", 15.0);
+        }};
+
+        Struct actualStruct = StructType.INSTANCE.fromValue(attributes, null);
+        assertTrue(Arrays.equals(actualStruct.getAttributes(), attributes.entrySet().toArray()));
+        assertEquals(actualStruct.getAttributes().length, 3);
+        assertEquals(actualStruct, new StructImpl(StructType.INSTANCE.getTypeName(), attributes.entrySet().toArray()));
+    }
+
+    @Test
+    public void testNestedStructTypeFromValue() throws SQLException {
+        Map<String, Object> attributes = new HashMap<>();
+        attributes.put("attribute1", "value1");
+        attributes.put("attribute2", 2);
+
+        Map<String, Object> nestedAttributes = new HashMap<>();
+        nestedAttributes.put("struct", attributes);
+        nestedAttributes.put("string", "hello");
+        nestedAttributes.put("int", 1);
+
+        Struct actualStruct = StructType.INSTANCE.fromValue(nestedAttributes, null);
+        assertTrue(Arrays.equals(actualStruct.getAttributes(), nestedAttributes.entrySet().toArray()));
+        assertEquals(actualStruct, new StructImpl(StructType.INSTANCE.getTypeName(), nestedAttributes.entrySet().toArray()));
+    }
+ }