### Question:
StringSimpleFieldActions implements AtlasFieldAction { @AtlasActionProcessor public static String trim(Trim action, String input) { if (input == null || input.length() == 0) { return input; } return input.trim(); }  @AtlasActionProcessor static String capitalize(Capitalize action, String input); @AtlasActionProcessor static String fileExtension(FileExtension action, String input); @AtlasActionProcessor static String lowercase(Lowercase action, String input); @AtlasActionProcessor static Character lowercaseChar(LowercaseChar action, Character input); @AtlasActionProcessor static String normalize(Normalize action, String input); @AtlasActionProcessor static String removeFileExtension(RemoveFileExtension action, String input); @AtlasActionProcessor static String separateByDash(SeparateByDash action, String input); @AtlasActionProcessor static String separateByUnderscore(SeparateByUnderscore action, String input); @AtlasActionProcessor static String trim(Trim action, String input); @AtlasActionProcessor static String trimLeft(TrimLeft action, String input); @AtlasActionProcessor static String trimRight(TrimRight action, String input); @AtlasActionProcessor static String uppercase(Uppercase action, String input); @AtlasActionProcessor static Character uppercaseChar(UppercaseChar action, Character input); static final String STRING_SEPARATOR_REGEX; static final Pattern STRING_SEPARATOR_PATTERN; }### Answer:
@Test public void testTrim() { assertNull(StringSimpleFieldActions.trim(new Trim(), null)); assertEquals("", StringSimpleFieldActions.trim(new Trim(), "")); assertEquals("foo", StringSimpleFieldActions.trim(new Trim(), " foo ")); assertEquals("Foo", StringSimpleFieldActions.trim(new Trim(), " Foo")); assertEquals("fOo", StringSimpleFieldActions.trim(new Trim(), "fOo ")); assertEquals("foO", StringSimpleFieldActions.trim(new Trim(), " foO ")); assertEquals("FOO", StringSimpleFieldActions.trim(new Trim(), "\t\n FOO")); assertEquals("FOO", StringSimpleFieldActions.trim(new Trim(), "\t\n FOO\f\r")); }