code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC licenses this file
  // to you under the Apache License, Version 2.0 (the
  // "License"); you may not use this file except in compliance
  // with the License.  You may obtain a copy of the License at
  //
  //   http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing,
  // software distributed under the License is distributed on an
  // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  // KIND, either express or implied.  See the License for the
  // specific language governing permissions and limitations
  // under the License.
  
  package org.openqa.selenium;
  
  import static org.assertj.core.api.Assertions.assertThat;
  import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
  import static org.openqa.selenium.Keys.LEFT;
  import static org.openqa.selenium.Keys.chord;
  import static org.openqa.selenium.Keys.getKeyFromUnicode;
  
  import org.junit.jupiter.api.Tag;
  import org.junit.jupiter.api.Test;
  
  @Tag("UnitTests")
  class KeysTest {
  
    @Test
    void charAtPosition0ReturnsKeyCode() {
      assertThat(Keys.LEFT.charAt(0)).isNotEqualTo(0);
    }
  
    @Test
    void charAtOtherPositionReturnsZero() {
      assertThat(Keys.LEFT.charAt(10)).isEqualTo((char) 0);
    }
  
    @Test
    void lengthIsAlwaysOne() {
      assertThat(LEFT.length()).isEqualTo(1);
    }
  
    @Test
    void validSubSequence() {
      assertThat(String.valueOf(LEFT)).isEqualTo(LEFT.subSequence(0, 1));
    }
  
    @Test
    void invalidSubSequenceThrows() {
      assertThatExceptionOfType(IndexOutOfBoundsException.class)
          .isThrownBy(() -> LEFT.subSequence(-1, 10));
    }
  
    @Test
    void buildChord() {
      CharSequence[] sequences = {"foo", Keys.LEFT};
      assertThat(chord(sequences)).isEqualTo("foo\uE012\uE000");
    }
  
    @Test
    void keyForCharacterCode() {
      Keys key = Keys.LEFT;
      assertThat((CharSequence) getKeyFromUnicode(key.charAt(0))).isEqualTo(key);
    }
  }
  