GH-168 - Fix mutating containers by properties.

Fixes #168.

Author: michael-simons

neo4j-cypher-dsl/src/main/java/org/neo4j/cypherdsl/core/Operations.java

@@ -37,7 +37,7 @@
 final class Operations {
 
 	private static final java.util.Set<Class<? extends Expression>> VALID_MUTATORS =
-		Collections.unmodifiableSet(new HashSet<>(Arrays.asList(Property.class, MapExpression.class, Parameter.class)));
+		Collections.unmodifiableSet(new HashSet<>(Arrays.asList(MapExpression.class, Parameter.class)));
 
 	static Operation concat(Expression op1, Expression op2) {
 
@@ -113,7 +113,8 @@ static Operation mutate(Expression target, MapExpression value) {
 	static Operation mutate(Expression target, Expression value) {
 
 		Assertions.notNull(value, "New properties value must not be null");
-		Assertions.isTrue(VALID_MUTATORS.contains(value.getClass()), "A property container can only be mutated by a map, or a parameter or property pointing to a map.");
+		Assertions.isTrue(Property.class.isAssignableFrom(value.getClass()) || VALID_MUTATORS.contains(value.getClass()),
+			"A property container can only be mutated by a map, or a parameter or property pointing to a map.");
 
 		return Operation.create(target, Operator.MUTATE, value);
 	}

neo4j-cypher-dsl/src/test/java/org/neo4j/cypherdsl/core/IssueRelatedIT.java

@@ -36,12 +36,6 @@ class IssueRelatedIT {
 	private static final Renderer cypherRenderer = Renderer.getDefaultRenderer();
 	private final Node person = Cypher.node("Person").named("person");
 
-	@Test
-	void unionMustClearCache() {
-
-
-	}
-
 	@Test
 	void gh115() {
 		Node nodes = Cypher.node("Node").named("node").withProperties("id", Cypher.literalOf("node_42"));
@@ -605,6 +599,15 @@ void removeAllPropertiesShouldWork() {
 		assertThat(cypher).isEqualTo("MATCH (n:`DeleteMe`) SET n = {} SET n.newProperty = 'aValue' RETURN n");
 	}
 
+	@Test // GH-168
+	void containersMustBeMutatableByProperties() {
+
+		Node nodeA = Cypher.node("Target").named("t");
+		Node nodeB = Cypher.node("Source").named("s");
+		String cypher = Cypher.match(nodeA, nodeB).mutate(nodeA, nodeB.property("whatever")).build().getCypher();
+		assertThat(cypher).isEqualTo("MATCH (t:`Target`), (s:`Source`) SET t += s.whatever");
+	}
+
 	@ParameterizedTest // GH-152
 	@MethodSource("relpatternChainingArgs")
 	void relpatternChaining(boolean multihops, int length, boolean backward, String expected) {