### Question:
StringSimpleFieldActions implements AtlasFieldAction { @AtlasActionProcessor public static String removeFileExtension(RemoveFileExtension action, String input) { if (input == null) { return null; } int ndx = input.lastIndexOf('.'); return ndx < 0 ? input : input.substring(0, ndx); }  @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 testRemoveFileExtension() { assertNull(StringSimpleFieldActions.removeFileExtension(null, null)); assertEquals("", StringSimpleFieldActions.removeFileExtension(null, "")); assertEquals("foo", StringSimpleFieldActions.removeFileExtension(null, "foo")); assertEquals("", StringSimpleFieldActions.removeFileExtension(null, ".")); assertEquals("foo", StringSimpleFieldActions.removeFileExtension(null, "foo.")); assertEquals("foo", StringSimpleFieldActions.removeFileExtension(null, "foo.bar")); assertEquals("foo.foo", StringSimpleFieldActions.removeFileExtension(null, "foo.foo.bar")); }