### Question:
IdentifierValidationUtil { public static void validateMetaTags(final TestDefinition definition) { final List<String> invalidMetaTags = definition.getMetaTags() .stream() .filter((metaTag) -> !isValidMetaTag(metaTag)) .collect(Collectors.toList()); if (!invalidMetaTags.isEmpty()) { throw new IllegalArgumentException( "Meta Tag must \n" + " - be alpha-numeric underscore\n" + " - not be longer than " + META_TAG_LENGTH_LIMIT + "\n" + " but found: " + invalidMetaTags ); } }  static void validateMetaTags(final TestDefinition definition); static void validateTestName(final String testName); static boolean isValidBucketName(final String bucketName);  }### Answer:
@Test public void testIsValidMetaTags() { final TestDefinition invalidMetaTagDefinition = createTestDefinition(ImmutableList.of("0", "_", "a", "__")); final TestDefinition emptyMetaTagDefinition = createTestDefinition(ImmutableList.of()); final TestDefinition validMetaTagDefinition = createTestDefinition(ImmutableList.of("a", "a_a")); assertThatThrownBy(() -> validateMetaTags(invalidMetaTagDefinition)) .isInstanceOf(IllegalArgumentException.class) .hasMessageContaining("Meta Tag must \n" + " - be alpha-numeric underscore\n" + " - not be longer than 100\n" + " but found: [_, __]"); validateMetaTags(emptyMetaTagDefinition); validateMetaTags(validMetaTagDefinition); }