diff --git a/src/test/java/ua/net/uid/utils/helpers/IOHelperTest.java b/src/test/java/ua/net/uid/utils/helpers/IOHelperTest.java
new file mode 100644
index 0000000..fe5d7dd
--- /dev/null
+++ b/src/test/java/ua/net/uid/utils/helpers/IOHelperTest.java
@@ -0,0 +1,251 @@
+package ua.net.uid.utils.helpers;
+
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.Reader;
+import java.io.StringReader;
+import java.io.StringWriter;
+import java.io.Writer;
+import java.nio.charset.StandardCharsets;
+
+public class IOHelperTest {
+    private static final byte[] dataEmpty = {};
+    private static final byte[] dataShort = RandomHelper.randomString(1024, 1024).getBytes(StandardCharsets.UTF_8);
+    private static final byte[] dataLong = RandomHelper.randomString(16 * 1024, 32 * 1024).getBytes(StandardCharsets.UTF_8);
+
+    @Test
+    void testCopyStreamWithBuffer() throws IOException {
+        byte[] buffer = new byte[2048];
+        try (InputStream input = new ByteArrayInputStream(dataEmpty)) {
+            ByteArrayOutputStream output = new ByteArrayOutputStream();
+            assertEquals(dataEmpty.length, IOHelper.copy(input, output, buffer));
+            assertArrayEquals(dataEmpty, output.toByteArray());
+        }
+        try (InputStream input = new ByteArrayInputStream(dataShort)) {
+            ByteArrayOutputStream output = new ByteArrayOutputStream();
+            assertEquals(dataShort.length, IOHelper.copy(input, output, buffer));
+            assertArrayEquals(dataShort, output.toByteArray());
+        }
+        try (InputStream input = new ByteArrayInputStream(dataLong)) {
+            ByteArrayOutputStream output = new ByteArrayOutputStream();
+            assertEquals(dataLong.length, IOHelper.copy(input, output, buffer));
+            assertArrayEquals(dataLong, output.toByteArray());
+        }
+    }
+
+    @Test
+    void testCopyStreamWithBufferSize() throws IOException {
+        try (InputStream input = new ByteArrayInputStream(dataEmpty)) {
+            ByteArrayOutputStream output = new ByteArrayOutputStream();
+            assertEquals(dataEmpty.length, IOHelper.copy(input, output, 4096));
+            assertArrayEquals(dataEmpty, output.toByteArray());
+        }
+        try (InputStream input = new ByteArrayInputStream(dataShort)) {
+            ByteArrayOutputStream output = new ByteArrayOutputStream();
+            assertEquals(dataShort.length, IOHelper.copy(input, output, 4096));
+            assertArrayEquals(dataShort, output.toByteArray());
+        }
+        try (InputStream input = new ByteArrayInputStream(dataLong)) {
+            ByteArrayOutputStream output = new ByteArrayOutputStream();
+            assertEquals(dataLong.length, IOHelper.copy(input, output, 4096));
+            assertArrayEquals(dataLong, output.toByteArray());
+        }
+    }
+
+    @Test
+    void testCopyStreamWithDefault() throws IOException {
+        try (InputStream input = new ByteArrayInputStream(dataEmpty)) {
+            ByteArrayOutputStream output = new ByteArrayOutputStream();
+            assertEquals(dataEmpty.length, IOHelper.copy(input, output));
+            assertArrayEquals(dataEmpty, output.toByteArray());
+        }
+        try (InputStream input = new ByteArrayInputStream(dataShort)) {
+            ByteArrayOutputStream output = new ByteArrayOutputStream();
+            assertEquals(dataShort.length, IOHelper.copy(input, output));
+            assertArrayEquals(dataShort, output.toByteArray());
+        }
+        try (InputStream input = new ByteArrayInputStream(dataLong)) {
+            ByteArrayOutputStream output = new ByteArrayOutputStream();
+            assertEquals(dataLong.length, IOHelper.copy(input, output));
+            assertArrayEquals(dataLong, output.toByteArray());
+        }
+    }
+
+    @Test
+    void testCopyReaderWithBuffer() throws IOException {
+        char[] buffer = new char[2048];
+        {
+            String source = new String(dataEmpty, StandardCharsets.UTF_8);
+            try (Reader reader = new StringReader(source)) {
+                StringWriter writer = new StringWriter();
+                assertEquals(source.length(), IOHelper.copy(reader, writer, buffer));
+                assertEquals(source, writer.toString());
+            }
+        }
+        {
+            String source = new String(dataShort, StandardCharsets.UTF_8);
+            try (Reader reader = new StringReader(source)) {
+                StringWriter writer = new StringWriter();
+                assertEquals(source.length(), IOHelper.copy(reader, writer, buffer));
+                assertEquals(source, writer.toString());
+            }
+        }
+        {
+            String source = new String(dataLong, StandardCharsets.UTF_8);
+            try (Reader reader = new StringReader(source)) {
+                StringWriter writer = new StringWriter();
+                assertEquals(source.length(), IOHelper.copy(reader, writer, buffer));
+                assertEquals(source, writer.toString());
+            }
+        }
+    }
+
+    @Test
+    void testCopyReaderWithBufferSize() throws IOException {
+        {
+            String source = new String(dataEmpty, StandardCharsets.UTF_8);
+            try (Reader reader = new StringReader(source)) {
+                StringWriter writer = new StringWriter();
+                assertEquals(source.length(), IOHelper.copy(reader, writer, 4000));
+                assertEquals(source, writer.toString());
+            }
+        }
+        {
+            String source = new String(dataShort, StandardCharsets.UTF_8);
+            try (Reader reader = new StringReader(source)) {
+                StringWriter writer = new StringWriter();
+                assertEquals(source.length(), IOHelper.copy(reader, writer, 4000));
+                assertEquals(source, writer.toString());
+            }
+        }
+        {
+            String source = new String(dataLong, StandardCharsets.UTF_8);
+            try (Reader reader = new StringReader(source)) {
+                StringWriter writer = new StringWriter();
+                assertEquals(source.length(), IOHelper.copy(reader, writer, 4000));
+                assertEquals(source, writer.toString());
+            }
+        }
+    }
+
+    @Test
+    void testCopyReaderWithDefault() throws IOException {
+        {
+            String source = new String(dataEmpty, StandardCharsets.UTF_8);
+            try (Reader reader = new StringReader(source)) {
+                StringWriter writer = new StringWriter();
+                assertEquals(source.length(), IOHelper.copy(reader, writer));
+                assertEquals(source, writer.toString());
+            }
+        }
+        {
+            String source = new String(dataShort, StandardCharsets.UTF_8);
+            try (Reader reader = new StringReader(source)) {
+                StringWriter writer = new StringWriter();
+                assertEquals(source.length(), IOHelper.copy(reader, writer));
+                assertEquals(source, writer.toString());
+            }
+        }
+        {
+            String source = new String(dataLong, StandardCharsets.UTF_8);
+            try (Reader reader = new StringReader(source)) {
+                StringWriter writer = new StringWriter();
+                assertEquals(source.length(), IOHelper.copy(reader, writer));
+                assertEquals(source, writer.toString());
+            }
+        }
+    }
+
+    @Test
+    void testToByteArrayWithBuffer() throws IOException {
+        assertArrayEquals(dataLong, IOHelper.toByteArray(new ByteArrayInputStream(dataLong), new byte[2048]));
+    }
+
+    @Test
+    void testToByteArrayWithBufferSize() throws IOException {
+        assertArrayEquals(dataLong, IOHelper.toByteArray(new ByteArrayInputStream(dataLong), 2048));
+    }
+
+    @Test
+    void testToByteArrayWithDefault() throws IOException {
+        assertArrayEquals(dataLong, IOHelper.toByteArray(new ByteArrayInputStream(dataLong)));
+    }
+
+    @Test
+    void testBufferedInput() {
+        InputStream src = null;
+        BufferedInputStream dst = null;
+
+        assertNull(IOHelper.buffered(src));
+
+        src = new ByteArrayInputStream(dataLong);
+        dst = IOHelper.buffered(src);
+        assertNotNull(dst);
+        assertNotSame(src, dst);
+        
+        src = dst;
+        dst = IOHelper.buffered(src);
+        assertNotNull(dst);
+        assertSame(src, dst);
+    }
+
+    @Test
+    void testBufferedOutput() {
+        OutputStream src = null;
+        BufferedOutputStream dst = null;
+
+        assertNull(IOHelper.buffered(src));
+
+        src = new ByteArrayOutputStream();
+        dst = IOHelper.buffered(src);
+        assertNotNull(dst);
+        assertNotSame(src, dst);
+        
+        src = dst;
+        dst = IOHelper.buffered(src);
+        assertNotNull(dst);
+        assertSame(src, dst);
+    }
+
+    @Test
+    void testBufferedReader() {
+        Reader src = null;
+        BufferedReader dst = null;
+
+        assertThrows(NullPointerException.class, () -> IOHelper.buffered((Reader) null));
+
+        src = new StringReader("");
+        dst = IOHelper.buffered(src);
+        assertNotSame(src, dst);
+        
+        src = dst;
+        dst = IOHelper.buffered(src);
+        assertSame(src, dst);
+    }
+
+    @Test
+    void testBufferedWriter() {
+        Writer src = null;
+        BufferedWriter dst = null;
+
+        assertThrows(NullPointerException.class, () -> IOHelper.buffered((Writer) null));
+
+        src = new StringWriter();
+        dst = IOHelper.buffered(src);
+        assertNotSame(src, dst);
+        
+        src = dst;
+        dst = IOHelper.buffered(src);
+        assertSame(src, dst);
+    }
+}