### Question:
UrlUtils { public static String concat(String baseUriSpec, String uriSpec) { if (baseUriSpec != null && !baseUriSpec.endsWith(PATH_SEPARATOR)) { baseUriSpec = baseUriSpec + PATH_SEPARATOR; } URI baseUri = uriFromSpec(baseUriSpec); if (baseUri != null && uriSpec != null && uriSpec.startsWith(PATH_SEPARATOR)) { uriSpec = uriSpec.substring(1); } URI uri = uriFromSpec(uriSpec); if (baseUri != null) { return uri == null ? baseUri.toString() : baseUri.resolve(uri).toString(); } else if (uri != null) { return uri.toString(); } else { return null; } } private  UrlUtils(); static String concat(String baseUriSpec, String uriSpec); static String sanitizeBaseUrl(String baseUriSpec, String uriSpec); static String getAbsoluteUrlFromFile(String file); static String getAbsoluteUrlPathFromFile(String file);  }### Answer:
@Test public void testBaseUrlWithoutTrailingSlash() { String test = UrlUtils.concat("http: Assertions.assertThat(test).isEqualTo("http: }
@Test public void testBaseUrlWithTrailingSlash() { String test = UrlUtils.concat("http: Assertions.assertThat(test).isEqualTo("http: }
@Test public void testBaseUrlWithPathWithoutTrailingSlash() { String test = UrlUtils.concat("http: Assertions.assertThat(test).isEqualTo("http: }
@Test public void testBaseUrlWithPathWithTrailingSlash() { String test = UrlUtils.concat("http: Assertions.assertThat(test).isEqualTo("http: }
@Test public void testBaseUrlWithoutTrailingSlashRootPath() { String test = UrlUtils.concat("http: Assertions.assertThat(test).isEqualTo("http: }
@Test public void testBaseUrlWithTrailingSlashRootPath() { String test = UrlUtils.concat("http: Assertions.assertThat(test).isEqualTo("http: }
@Test public void testBaseUrlWithPathWithoutTrailingSlashRootPath() { String test = UrlUtils.concat("http: Assertions.assertThat(test).isEqualTo("http: }
@Test public void testBaseUrlWithPathWithTrailingSlashRootPath() { String test = UrlUtils.concat("http: Assertions.assertThat(test).isEqualTo("http: }
@Test public void testBaseUrlNullUrlDefined() { String test = UrlUtils.concat(null, "/abc/def"); Assertions.assertThat(test).isEqualTo("/abc/def"); }
@Test public void testBaseUrlDefinedUrlNull() { String test = UrlUtils.concat("http: Assertions.assertThat(test).isEqualTo("http: }
@Test public void testBaseUrlNullUrlNull() { String test = UrlUtils.concat(null, null); Assertions.assertThat(test).isNull(); }
@Test public void testAbsoluteUrlReplaceBaseUrl() { String test = UrlUtils.concat("http: Assertions.assertThat(test).isEqualTo("http: }