### Question:
SpringExpressionParser { public String parse(String expressionString) { if (expressionString != null) { Expression expression = parser.parseExpression(expressionString, templateContext); expressionString = expression.getValue(evalContext).toString(); } return expressionString; } SpringExpressionParser();   SpringExpressionParser(Class<?>... functionHolders); String parse(String expressionString);  }### Answer:
@Test public void literal() { assertThat(parser.parse("local_hour > 0"), is("local_hour > 0")); }
@Test public void empty() { assertThat(parser.parse(""), is("")); }
@Test public void blank() { assertThat(parser.parse(" "), is(" ")); }
@Test public void nullValue() { assertThat(parser.parse(null), is((Object) null)); }
@Test public void literalWithNowFunction() { assertThat(parser.parse("local_date > #{ #now().minusDays(30).toString('yyyy-MM-dd')}"), is("local_date > 2016-02-23")); }
@Test public void spaceBeforeRootContextReference() { assertThat(parser.parse("local_date >= '#{ #nowUtc().minusDays(2).toString(\"yyyy-MM-dd\") }'"), is("local_date >= '2016-03-22'")); }