WordWrap.java

package logic;

public class WordWrap {

  public static String wrap(String input, int length) {
    return null;
  }

}

WordWrapTest1.java

package logic;

import org.junit.Test;

public class WordWrapTest {

  @Test
  public void testName() throws Exception {
    WordWrap.wrap(null, 10);
  }
}

WordWrapTest2.java

package logic;

import org.junit.Test;

import static logic.WordWrap.wrap;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

public class WordWrapTest {

  @Test
  public void wrap_null_return_empty_string() throws Exception {
    assertThat(wrap(null, 10), is(""));
  }

  @Test
  public void wrap_empty_string_returns_empty_string() throws Exception {
    assertThat(wrap("", 10), is(""));
  }

  @Test(expected = IllegalArgumentException.class)
  public void length_less_than_one__throw_invalid_argument() throws Exception {
    wrap("xxx", 0);
  }

  @Test
  public void one_short_word_dosent_wrap() throws Exception {
    assertThat(wrap("привет", 10), is("привет"));
  }


}