SpEL: 'select last' operator for maps has inconsistent behavior [SPR-7323]

[spring-projects-issues]

Sam Brannen opened SPR-7323 and commented

The inconsistent behavior is due to improper tracking of the lastKey for maps in Selection.getValueInternal(ExpressionState).

The following can be used to reproduce the bug:

class MapTestBean {

	private final Map<String, String> colors = new TreeMap<String, String>();

	MapTestBean() {
		colors.put("red", "rot");
		colors.put("brown", "braun");
		colors.put("blue", "blau");
		colors.put("yellow", "gelb");
		colors.put("beige", "beige");
	}

	public Map<String, String> getColors() {
		return colors;
	}
}

EvaluationContext context = new StandardEvaluationContext(new MapTestBean());
ExpressionParser parser = new SpelExpressionParser();

Expression exp = parser.parseExpression("colors.$[key.startsWith('b')]");
Map<String, String> colorsMap = (Map<String, String>) exp.getValue(context);

assertEquals(1, colorsMap.size());
assertEquals("brown", colorsMap.keySet().iterator().next());

The above test currently fails with:

org.junit.ComparisonFailure: expected:<[brown]> but was:<[yellow]>

---

Affects: 3.0.3

Referenced from: commits 8bd0633, db7531b

[spring-projects-issues]

Sam Brannen commented

Added code to reproduce bug.

[spring-projects-issues]

Sam Brannen commented

SpEL 'select last' operator now works consistently with maps.