### Question:
GitUtils { public String show(Repository repository, String revstr) throws AmbiguousObjectException, IOException { byte[] bytes = showBytes(repository, revstr); if (bytes == null) { return null; } return new String(bytes, "UTF-8"); }  void addRemote(Repository toConfigure, String name, Repository remoteRepo); void fetch(Repository repository, String remote); RevCommit getCommit(Repository repo, String revstr); boolean containsCommit(Repository repository, String revstr); byte[] showBytes(Repository repository, String revstr); String show(Repository repository, String revstr); boolean isSha1(String candidate); Repository createRepository(File fullPath); String getTree(Repository repo, String commitSha1); void checkoutAsBranch(Repository repository, String commitSha1,
			String branchName);  }### Answer:
@Test public void testShow() throws Exception { assertThat(gitUtils.show(test, "HEAD:README")).isEqualTo("Readme\n"); assertThat(gitUtils.show(test, "HEAD^:README")).isEmpty(); assertThat(gitUtils.show(test, "HEAD:unknown")).isNull(); }