### Question:
StringSimpleFieldActions implements AtlasFieldAction { @AtlasActionProcessor public static String trimLeft(TrimLeft action, String input) { if (input == null || input.length() == 0) { return input; } int i = 0; while (i < input.length() && Character.isWhitespace(input.charAt(i))) { i++; } return input.substring(i); }  @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 testTrimLeft() { assertNull(StringSimpleFieldActions.trimLeft(new TrimLeft(), null)); assertEquals("", StringSimpleFieldActions.trimLeft(new TrimLeft(), "")); assertEquals("foo ", StringSimpleFieldActions.trimLeft(new TrimLeft(), " foo ")); assertEquals("Foo", StringSimpleFieldActions.trimLeft(new TrimLeft(), " Foo")); assertEquals("fOo ", StringSimpleFieldActions.trimLeft(new TrimLeft(), "fOo ")); assertEquals("foO ", StringSimpleFieldActions.trimLeft(new TrimLeft(), " foO ")); assertEquals("FOO", StringSimpleFieldActions.trimLeft(new TrimLeft(), "\t\n FOO")); assertEquals("FOO\f\r", StringSimpleFieldActions.trimLeft(new TrimLeft(), "\t\n FOO\f\r")); }