Avoid excluding parent poms

In 3d05983, the fix for gh-310, an attempt was made to prevent
dependencies in a transitive platform dependency from stoping
exclusions from being applied correctly. Unfortunately, it went
to far which led to a dependency's parent pom being excluded. This
could cause resolution failures if that parent contained
dependency management that was required for the child's dependencies
to resolve correctly.

This commit reworks that changes so that the platform dependency
itself is added to the included nodes but to then stop processing.
This prevents the platform dependency itself from being excluded but
ensures that any of its dependencies due not influence the
application of exclusions.

Fixes gh-360

src/main/java/io/spring/gradle/dependencymanagement/internal/ExclusionConfiguringAction.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2022 the original author or authors.
+ * Copyright 2014-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -135,19 +135,21 @@ private Configuration copyConfiguration() {
 	private Set<DependencyCandidate> determineIncludedComponents(ResolvedComponentResult root,
 			Map<String, Exclusions> pomExclusionsById) {
 		LinkedList<Node> queue = new LinkedList<>();
-		queue.add(new Node(root, getId(root), new HashSet<>()));
+		queue.add(new Node(root, getId(root), new HashSet<>(), false));
 		Set<ResolvedComponentResult> seen = new HashSet<>();
 		Set<DependencyCandidate> includedComponents = new HashSet<>();
 		while (!queue.isEmpty()) {
 			Node node = queue.remove();
 			includedComponents.add(new DependencyCandidate(node.component.getModuleVersion()));
-			for (DependencyResult dependency : node.component.getDependencies()) {
-				if (dependency instanceof ResolvedDependencyResult) {
-					handleResolvedDependency((ResolvedDependencyResult) dependency, node, pomExclusionsById, queue,
-							seen);
-				}
-				else if (dependency instanceof UnresolvedDependencyResult) {
-					handleUnresolvedDependency((UnresolvedDependencyResult) dependency, node, includedComponents);
+			if (!node.platform) {
+				for (DependencyResult dependency : node.component.getDependencies()) {
+					if (dependency instanceof ResolvedDependencyResult) {
+						handleResolvedDependency((ResolvedDependencyResult) dependency, node, pomExclusionsById, queue,
+								seen);
+					}
+					else if (dependency instanceof UnresolvedDependencyResult) {
+						handleUnresolvedDependency((UnresolvedDependencyResult) dependency, node, includedComponents);
+					}
 				}
 			}
 		}
@@ -157,12 +159,10 @@ else if (dependency instanceof UnresolvedDependencyResult) {
 	private void handleResolvedDependency(ResolvedDependencyResult dependency, Node node,
 			Map<String, Exclusions> pomExclusionsById, LinkedList<Node> queue, Set<ResolvedComponentResult> seen) {
 		ResolvedComponentResult child = dependency.getSelected();
-		if (isPlatform(child)) {
-			return;
-		}
 		String childId = getId(child);
 		if (!node.excluded(childId) && seen.add(child)) {
-			queue.add(new Node(child, childId, getChildExclusions(node, childId, pomExclusionsById)));
+			boolean platform = isPlatform(child);
+			queue.add(new Node(child, childId, getChildExclusions(node, childId, pomExclusionsById), platform));
 		}
 	}
 
@@ -225,10 +225,13 @@ private static final class Node {
 
 		private final Set<Exclusion> exclusions;
 
-		private Node(ResolvedComponentResult component, String id, Set<Exclusion> exclusions) {
+		private final boolean platform;
+
+		private Node(ResolvedComponentResult component, String id, Set<Exclusion> exclusions, boolean platform) {
 			this.component = component;
 			this.id = id;
 			this.exclusions = exclusions;
+			this.platform = platform;
 		}
 
 		private boolean excluded(String id) {

src/test/java/io/spring/gradle/dependencymanagement/DependencyManagementPluginIntegrationTests.java

@@ -488,6 +488,13 @@ void constraintsInTransitivePlatformDependenciesDoNotPreventExclusionsFromWorkin
 		assertThat(readLines("resolved.txt")).noneMatch((line) -> line.contains("junit"));
 	}
 
+	@Test
+	void resolutionSucceedsWhenDependencyReliesOnDependencyManagementFromItsAncestors() {
+		this.gradleBuild.runner().withArguments("resolve").build();
+		assertThat(readLines("resolved.txt")).containsExactly("dependency-management-child-1.0.jar",
+				"spring-core-5.3.27.jar", "spring-jcl-5.3.27.jar");
+	}
+
 	private void writeLines(Path path, String... lines) {
 		try {
 			Path resolvedPath = this.gradleBuild.runner().getProjectDir().toPath().resolve(path);

src/test/resources/io/spring/gradle/dependencymanagement/DMPIT/resolutionSucceedsWhenDependencyReliesOnDependencyManagementFromItsAncestors.gradle

@@ -0,0 +1,24 @@
+plugins {
+	id "java"
+	id "io.spring.dependency-management"
+}
+
+repositories {
+	maven {
+		url file("maven-repo")
+	}
+	mavenCentral()
+}
+
+dependencies {
+	implementation("test:dependency-management-child:1.0");
+}
+
+tasks.register("resolve") {
+	doFirst {
+		def files = project.configurations.compileClasspath.resolve()
+		def output = new File("${buildDir}/resolved.txt")
+		output.parentFile.mkdirs()
+		files.collect { it.name }.each { output << "${it}\n" }
+	}
+}

src/test/resources/maven-repo/test/dependency-management-child/1.0/dependency-management-child-1.0.pom

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+
+	<parent>
+		<groupId>test</groupId>
+		<artifactId>dependency-management-parent</artifactId>
+		<version>1.0</version>
+		<relativePath></relativePath>
+	</parent>
+
+	<artifactId>dependency-management-child</artifactId>
+	<packaging>jar</packaging>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework</groupId>
+			<artifactId>spring-core</artifactId>
+		</dependency>
+	</dependencies>
+
+</project>

src/test/resources/maven-repo/test/dependency-management-grandparent/1.0/dependency-management-grandparent-1.0.pom

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+
+	<groupId>test</groupId>
+	<artifactId>dependency-management-grandparent</artifactId>
+	<version>1.0</version>
+	<packaging>pom</packaging>
+
+	<dependencyManagement>
+		<dependencies>
+			<dependency>
+				<groupId>org.springframework</groupId>
+				<artifactId>spring-core</artifactId>
+				<version>5.3.27</version>
+			</dependency>
+		</dependencies>
+	</dependencyManagement>
+
+
+</project>

src/test/resources/maven-repo/test/dependency-management-parent/1.0/dependency-management-parent-1.0.pom

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+
+	<parent>
+		<groupId>test</groupId>
+		<artifactId>dependency-management-grandparent</artifactId>
+		<version>1.0</version>
+		<relativePath></relativePath>
+	</parent>
+
+	<artifactId>dependency-management-parent</artifactId>
+	<packaging>pom</packaging>
+
+</project>