code: @Test public void renderWithReplacement() throws Exception {
    Resource resource=new ByteArrayResource("banner ${a} ${spring-boot.version} ${application.version}".getBytes());
    ResourceBanner banner=new ResourceBanner(resource);
    ConfigurableEnvironment environment=new MockEnvironment();
    Map<String,Object> source=Collections.<String,Object>singletonMap("a","1");
    environment.getPropertySources().addLast(new MapPropertySource("map",source));
    ByteArrayOutputStream out=new ByteArrayOutputStream();
    banner.printBanner(environment,getClass(),new PrintStream(out));
    assertThat(out.toString(),startsWith("banner 1"));
    assertThat(out.toString(),not(containsString("$")));
  }
  