Field existence check for the elements of a collection field #3349
Description
Describe the bug
It will report "fields don't exist" if trying to specify the compared fields for the elements of a collection field.
- assertj core version: 3.25.2
- java version: 17
- test framework version: JUnit 5
Test case reproducing the bug
@Data
static class Person {
private final String name, address;
private List<Person> friends = new ArrayList<>(), enemies = new ArrayList<>();
}
@Test
void listElementFieldComparison() {
Person sherlock1 = new Person("Sherlock Holmes", null);
sherlock1.friends.add(new Person("Dr. John Watson", null));
Person sherlock2 = new Person("Sherlock Holmes", null);
sherlock2.friends.add(new Person("Dr. John Watson", "Baker Street"));
assertThat(sherlock1).usingRecursiveComparison(RecursiveComparisonConfiguration.builder()
.withComparedFields("friends.name")
.build()).isEqualTo(sherlock2);
}The outcome
java.lang.IllegalArgumentException: The following fields don't exist: {name in <friends.name>}
at org.assertj.core.api.recursive.comparison.RecursiveComparisonConfiguration.checkComparedFieldsExist(RecursiveComparisonConfiguration.java:1092)
at org.assertj.core.api.recursive.comparison.RecursiveComparisonDifferenceCalculator$ComparisonState.initDualValuesToCompare(RecursiveComparisonDifferenceCalculator.java:146)
at org.assertj.core.api.recursive.comparison.RecursiveComparisonDifferenceCalculator$ComparisonState.access$100(RecursiveComparisonDifferenceCalculator.java:73)
at org.assertj.core.api.recursive.comparison.RecursiveComparisonDifferenceCalculator.determineDifferences(RecursiveComparisonDifferenceCalculator.java:237)
at org.assertj.core.api.recursive.comparison.RecursiveComparisonDifferenceCalculator.determineDifferences(RecursiveComparisonDifferenceCalculator.java:228)
at org.assertj.core.api.RecursiveComparisonAssert.determineDifferencesWith(RecursiveComparisonAssert.java:1770)
at org.assertj.core.api.RecursiveComparisonAssert.isEqualTo(RecursiveComparisonAssert.java:157)Since I only use ComparingProperties as the RecursiveComparisonIntrospectionStrategy, so here is my temporary solution.
public class ComparingProperties extends org.assertj.core.api.recursive.comparison.ComparingProperties {
@Override
public Set<String> getChildrenNodeNamesOf(Object node) {
if (node instanceof Collection<?> c) {
Iterator<?> i = c.iterator(); if (!i.hasNext()) return Collections.emptySet();
return getChildrenNodeNamesOf(i.next());
}
return super.getChildrenNodeNamesOf(node);
}
@Override
public Object getChildNodeValue(String childNodeName, Object instance) {
if (instance instanceof Collection<?> c) {
Iterator<?> i = c.iterator(); if (!i.hasNext()) return null;
return getChildNodeValue(childNodeName, i.next());
}
Object v = super.getChildNodeValue(childNodeName, instance);
if (v instanceof Collection<?> c && c.isEmpty()) return null;
return v;
}
}