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Fix ClassCastException in ConstraintChecker.STORAGE_READER_CONSTRAINT_BUILDER #37

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Fix ClassCastException in ConstraintChecker.STORAGE_READER_CONSTRAINT_BUILDER #37

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1021200
Fix ClassCastException in ConstraintChecker.STORAGE_READER_CONSTRAINT…
tsetso-spread Mar 17, 2026
cc4d063
Improve ConstraintChecker tests: use real objects and test constraint…
tsetso-spread Mar 18, 2026
22f99f9
Apply spotless formatting
tsetso-spread Mar 18, 2026
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5 changes: 3 additions & 2 deletions core/src/main/java/org/neo4j/kernel/impl/constraints/ConstraintChecker.java
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Original file line number Diff line number Diff line change
Expand Up @@ -79,11 +79,12 @@ TxStateVisitor visit(
ConstraintDescriptor constraintDescriptor = it.next();
if (constraintDescriptor.enforcesPropertyExistence()) {
if (constraintDescriptor.schema().isSchemaDescriptorType(LabelSchemaDescriptor.class)) {
nodeLabelSchemaDescriptors.add((LabelSchemaDescriptor) constraintDescriptor);
nodeLabelSchemaDescriptors.add((LabelSchemaDescriptor) constraintDescriptor.schema());
}

if (constraintDescriptor.schema().isSchemaDescriptorType(RelationTypeSchemaDescriptor.class)) {
relsLabelSchemaDescriptors.add((RelationTypeSchemaDescriptor) constraintDescriptor);
relsLabelSchemaDescriptors.add(
(RelationTypeSchemaDescriptor) constraintDescriptor.schema());
}
}
}
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129 changes: 121 additions & 8 deletions core/src/test/java/org/neo4j/kernel/impl/constraints/ConstraintCheckerTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -9,17 +9,21 @@
*/
package org.neo4j.kernel.impl.constraints;

import static org.junit.jupiter.api.Assertions.*;
import static org.assertj.core.api.Assertions.assertThat;
import static org.assertj.core.api.Assertions.assertThatThrownBy;
import static org.mockito.Mockito.*;
import static org.neo4j.kernel.impl.constraints.ConstraintChecker.EMPTY_CHECKER;
import static org.neo4j.kernel.impl.constraints.ConstraintChecker.STORAGE_READER_CONSTRAINT_BUILDER;

import java.util.Collections;
import org.eclipse.collections.api.set.primitive.IntSet;
import java.util.List;
import org.eclipse.collections.impl.factory.primitive.IntSets;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.neo4j.common.TokenNameLookup;
import org.neo4j.internal.kernel.api.TokenSet;
import org.neo4j.internal.schema.*;
import org.neo4j.internal.schema.constraints.ConstraintDescriptorFactory;
import org.neo4j.kernel.api.exceptions.schema.NodePropertyExistenceException;
import org.neo4j.storageengine.api.StorageReader;

Expand All @@ -38,16 +42,125 @@ public void testStorageReaderConstraintBuilder_EmptyConstraints() {

ConstraintChecker result = STORAGE_READER_CONSTRAINT_BUILDER.apply(storageReaderMock);

// Check if it returns the empty checker when there are no constraints
assertSame(EMPTY_CHECKER, result);
assertThat(result).isSameAs(EMPTY_CHECKER);
}

@Test
public void testCheckNode_NoViolations() throws NodePropertyExistenceException {
public void testStorageReaderConstraintBuilder_SkipsNonExistenceConstraints() {
ConstraintDescriptor constraintDescriptor = mock(ConstraintDescriptor.class);
when(constraintDescriptor.enforcesPropertyExistence()).thenReturn(false);

when(storageReaderMock.constraintsGetAll())
.thenReturn(List.of(constraintDescriptor).iterator());

ConstraintChecker result = STORAGE_READER_CONSTRAINT_BUILDER.apply(storageReaderMock);

assertThat(result).isSameAs(EMPTY_CHECKER);
}

@Test
public void testStorageReaderConstraintBuilder_NodePropertyExistenceConstraint() {
// Regression test: STORAGE_READER_CONSTRAINT_BUILDER previously cast constraintDescriptor
// directly to LabelSchemaDescriptor instead of constraintDescriptor.schema(), causing
// a ClassCastException at commit time for databases with property existence constraints.
int labelId = 1;
int propertyId = 10;
LabelSchemaDescriptor labelSchema = SchemaDescriptors.forLabel(labelId, propertyId);
ConstraintDescriptor constraint = ConstraintDescriptorFactory.existsForSchema(labelSchema, false);

when(storageReaderMock.constraintsGetAll())
.thenReturn(List.of(constraint).iterator());

ConstraintChecker result = STORAGE_READER_CONSTRAINT_BUILDER.apply(storageReaderMock);

assertThat(result).isNotSameAs(EMPTY_CHECKER);
assertThat(result.getNodeLabelSchemaDescriptors()).hasSize(1);
assertThat(result.getNodeLabelSchemaDescriptors().get(0).getLabelId()).isEqualTo(labelId);
assertThat(result.getNodeLabelSchemaDescriptors().get(0).getPropertyIds())
.containsExactly(propertyId);
assertThat(result.getRelationTypeSchemaDescriptors()).isEmpty();
assertThat(result.getNodePropertyMap().containsKey(labelId)).isTrue();
assertThat(result.getNodePropertyMap().get(labelId)).containsExactly(propertyId);
}

@Test
public void testStorageReaderConstraintBuilder_RelPropertyExistenceConstraint() {
int relTypeId = 2;
int propertyId = 20;
RelationTypeSchemaDescriptor relSchema = SchemaDescriptors.forRelType(relTypeId, propertyId);
ConstraintDescriptor constraint = ConstraintDescriptorFactory.existsForSchema(relSchema, false);

when(storageReaderMock.constraintsGetAll())
.thenReturn(List.of(constraint).iterator());

ConstraintChecker result = STORAGE_READER_CONSTRAINT_BUILDER.apply(storageReaderMock);

assertThat(result).isNotSameAs(EMPTY_CHECKER);
assertThat(result.getNodeLabelSchemaDescriptors()).isEmpty();
assertThat(result.getRelationTypeSchemaDescriptors()).hasSize(1);
assertThat(result.getRelationTypeSchemaDescriptors().get(0).getRelTypeId())
.isEqualTo(relTypeId);
assertThat(result.getRelationTypeSchemaDescriptors().get(0).getPropertyIds())
.containsExactly(propertyId);
assertThat(result.getRelPropertyMap().containsKey(relTypeId)).isTrue();
assertThat(result.getRelPropertyMap().get(relTypeId)).containsExactly(propertyId);
}

@Test
public void testCheckNode_PassesWhenRequiredPropertyPresent() throws NodePropertyExistenceException {
int labelId = 5;
int requiredPropertyId = 42;
LabelSchemaDescriptor labelSchema = SchemaDescriptors.forLabel(labelId, requiredPropertyId);

ConstraintChecker checker =
new ConstraintChecker(storageReaderMock, Collections.emptyList(), Collections.emptyList());
new ConstraintChecker(storageReaderMock, List.of(labelSchema), Collections.emptyList());

TokenSet tokenSet = mock(TokenSet.class);
when(tokenSet.numberOfTokens()).thenReturn(1);
when(tokenSet.token(0)).thenReturn(labelId);

checker.checkNode(1L, tokenSet, IntSets.immutable.of(requiredPropertyId));
}

@Test
public void testCheckNode_DetectsViolationForMissingRequiredProperty() {
int labelId = 5;
int requiredPropertyId = 42;
LabelSchemaDescriptor labelSchema = SchemaDescriptors.forLabel(labelId, requiredPropertyId);
ConstraintDescriptor constraint = ConstraintDescriptorFactory.existsForSchema(labelSchema, false);

TokenNameLookup tokenNameLookup = mock(TokenNameLookup.class);
when(tokenNameLookup.labelGetName(labelId)).thenReturn("TestLabel");
when(tokenNameLookup.propertyKeyGetName(requiredPropertyId)).thenReturn("requiredProp");
when(storageReaderMock.constraintsGetForSchema(labelSchema))
.thenReturn(List.of(constraint).iterator());
when(storageReaderMock.tokenNameLookup()).thenReturn(tokenNameLookup);

ConstraintChecker checker =
new ConstraintChecker(storageReaderMock, List.of(labelSchema), Collections.emptyList());

TokenSet tokenSet = mock(TokenSet.class);
when(tokenSet.numberOfTokens()).thenReturn(1);
when(tokenSet.token(0)).thenReturn(labelId);

assertThatThrownBy(() -> checker.checkNode(1L, tokenSet, IntSets.immutable.empty()))
.isInstanceOf(NodePropertyExistenceException.class);
}

@Test
public void testCheckNode_NoViolationsWhenLabelDoesNotMatch() throws NodePropertyExistenceException {
int constrainedLabelId = 5;
int requiredPropertyId = 42;
LabelSchemaDescriptor labelSchema = SchemaDescriptors.forLabel(constrainedLabelId, requiredPropertyId);

ConstraintChecker checker =
new ConstraintChecker(storageReaderMock, List.of(labelSchema), Collections.emptyList());

// Node has a different label (99), so the constraint on label 5 should not apply
TokenSet tokenSet = mock(TokenSet.class);
when(tokenSet.numberOfTokens()).thenReturn(1);
when(tokenSet.token(0)).thenReturn(99);

// Ideally, no exception should be thrown if no constraint is violated
assertDoesNotThrow(() -> checker.checkNode(1, mock(TokenSet.class), mock(IntSet.class)));
checker.checkNode(1L, tokenSet, IntSets.immutable.empty());
}
}