从JUnit测试确认FileReader已正确关闭

import org.junit.jupiter.api.Test;

import java.io.FileReader;
import java.io.IOException;

import static org.junit.jupiter.api.Assertions.assertEquals;

public class FileReaderTest {

    @Test
    public void testFileReader() throws IOException {
        String expectedContent = "This is a test file.";

        try (FileReader fileReader = new FileReader("test.txt")) {
            char[] buffer = new char[expectedContent.length()];
            fileReader.read(buffer);
            String actualContent = new String(buffer);
            assertEquals(expectedContent, actualContent);
        }
    }
}