### Question:
AwsUtil { public static StorageClass toStorageClass(String storageClass) { if (storageClass == null) { return null; } return StorageClass.fromValue(storageClass.toUpperCase(Locale.ROOT)); } private  AwsUtil(); static StorageClass toStorageClass(String storageClass);  }### Answer:
@Test public void toStorageClass() { assertThat(AwsUtil.toStorageClass("REDUCED_REDUNDANCY"), is(StorageClass.ReducedRedundancy)); }
@Test public void toNullStorageClass() { assertThat(AwsUtil.toStorageClass(null), is(nullValue())); }
@Test public void toStorageClassCaseSensitiveness() { assertThat(AwsUtil.toStorageClass("glacier"), is(StorageClass.Glacier)); assertThat(AwsUtil.toStorageClass("gLaCiEr"), is(StorageClass.Glacier)); }
@Test(expected = IllegalArgumentException.class) public void toInvalidStorageClass() { AwsUtil.toStorageClass("DEFAULT_STORAGE_CLASS"); }