Implement CharSequence interface by ReversedSequence class. Add Rever…

…sedSequence tests

Complete interfaces homework additional task.

java-oop-ru/interfaces/src/main/java/exercise/ReversedSequence.java

@@ -1,5 +1,31 @@
 package exercise;
 
 // BEGIN
+public class ReversedSequence implements CharSequence{
+    private String sequence;
+    public ReversedSequence(String sequence) {
+        var reversedSequence = new StringBuilder(sequence);
+        this.sequence = reversedSequence.reverse().toString();
+    }
 
+    @Override
+    public int length() {
+        return this.sequence.length();
+    }
+
+    @Override
+    public char charAt(int index) {
+        return this.sequence.toCharArray()[index];
+    }
+
+    @Override
+    public CharSequence subSequence(int start, int end) {
+        return this.sequence.substring(start, end);
+    }
+
+    @Override
+    public String toString() {
+        return this.sequence;
+    }
+}
 // END

java-oop-ru/interfaces/src/test/java/exercise/ReversedSequenceTest.java

@@ -0,0 +1,17 @@
+package exercise;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class ReversedSequenceTest {
+    CharSequence sequence = new ReversedSequence("abcdef");
+
+    @Test
+    public void testReversedSequence() {
+        assertEquals("fedcba", sequence.toString());
+        assertEquals('e', sequence.charAt(1));
+        assertEquals(6, sequence.length());
+        assertEquals("edc", sequence.subSequence(1, 4).toString());
+    }
+}