[MNG-1378] make test-jar dependencies transitive

impl/maven-impl/src/main/java/org/apache/maven/impl/resolver/MavenSessionBuilderSupplier.java

@@ -100,11 +100,13 @@ public DependencyManager getDependencyManager(boolean transitive) {
     }
 
     public DependencySelector getDependencySelector() {
+        DependencySelector scopeSelector = ScopeDependencySelector.legacy(
+                null, Arrays.asList(DependencyScope.TEST.id(), DependencyScope.PROVIDED.id()));
+        if (!mavenMaven3Personality) {
+            scopeSelector = new TestJarDependencySelector(scopeSelector);
+        }
         return new AndDependencySelector(
-                ScopeDependencySelector.legacy(
-                        null, Arrays.asList(DependencyScope.TEST.id(), DependencyScope.PROVIDED.id())),
-                OptionalDependencySelector.fromDirect(),
-                new ExclusionDependencySelector());
+                scopeSelector, OptionalDependencySelector.fromDirect(), new ExclusionDependencySelector());
     }
 
     public DependencyGraphTransformer getDependencyGraphTransformer() {

impl/maven-impl/src/main/java/org/apache/maven/impl/resolver/TestJarDependencySelector.java

@@ -0,0 +1,94 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.impl.resolver;
+
+import java.util.Objects;
+
+import org.apache.maven.api.DependencyScope;
+import org.apache.maven.api.Type;
+import org.eclipse.aether.artifact.ArtifactProperties;
+import org.eclipse.aether.collection.DependencyCollectionContext;
+import org.eclipse.aether.collection.DependencySelector;
+import org.eclipse.aether.graph.Dependency;
+
+import static java.util.Objects.requireNonNull;
+
+/**
+ * Preserves Maven's normal non-transitive test-scope semantics while allowing the direct test-scoped dependencies of
+ * a test JAR to participate in dependency collection. Those dependencies are part of the test artifact's classpath
+ * contract, not the producer's main artifact contract.
+ */
+final class TestJarDependencySelector implements DependencySelector {
+    private final DependencySelector delegate;
+    private final boolean testJarParent;
+
+    TestJarDependencySelector(DependencySelector delegate) {
+        this(delegate, false);
+    }
+
+    private TestJarDependencySelector(DependencySelector delegate, boolean testJarParent) {
+        this.delegate = requireNonNull(delegate, "delegate cannot be null");
+        this.testJarParent = testJarParent;
+    }
+
+    @Override
+    public boolean selectDependency(Dependency dependency) {
+        requireNonNull(dependency, "dependency cannot be null");
+        if (testJarParent && DependencyScope.TEST.id().equals(dependency.getScope())) {
+            return true;
+        }
+        return delegate.selectDependency(dependency);
+    }
+
+    @Override
+    public DependencySelector deriveChildSelector(DependencyCollectionContext context) {
+        requireNonNull(context, "context cannot be null");
+
+        DependencySelector childDelegate = delegate.deriveChildSelector(context);
+        Dependency parent = context.getDependency();
+        boolean childOfTestJar = parent != null
+                && Type.TEST_JAR.equals(parent.getArtifact().getProperty(ArtifactProperties.TYPE, ""));
+
+        if (childDelegate == delegate && childOfTestJar == testJarParent) {
+            return this;
+        }
+        return new TestJarDependencySelector(childDelegate, childOfTestJar);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (!(obj instanceof TestJarDependencySelector that)) {
+            return false;
+        }
+        return testJarParent == that.testJarParent && delegate.equals(that.delegate);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(delegate, testJarParent);
+    }
+
+    @Override
+    public String toString() {
+        return getClass().getSimpleName() + "[delegate=" + delegate + ", testJarParent=" + testJarParent + ']';
+    }
+}

its/core-it-suite/src/test/java/org/apache/maven/it/MavenITmng1378TestJarTransitiveDependenciesTest.java

@@ -0,0 +1,67 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.it;
+
+import java.nio.file.Path;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Integration test for <a href="https://issues.apache.org/jira/browse/MNG-1378">MNG-1378</a>.
+ */
+public class MavenITmng1378TestJarTransitiveDependenciesTest extends AbstractMavenIntegrationTestCase {
+
+    @Test
+    public void testTestJarCarriesProducerTestDependencies() throws Exception {
+        Path testDir = extractResources("mng-1378");
+
+        Verifier producer = newVerifier(testDir);
+        producer.setAutoclean(false);
+        producer.deleteArtifacts("org.apache.maven.its.mng1378");
+        producer.addCliArgument("-pl");
+        producer.addCliArgument("support,test-jar");
+        producer.addCliArgument("validate");
+        producer.execute();
+        producer.verifyErrorFreeLog();
+
+        Verifier consumer = newVerifier(testDir.resolve("consumer"));
+        consumer.setAutoclean(false);
+        consumer.addCliArgument("validate");
+        consumer.execute();
+        consumer.verifyErrorFreeLog();
+
+        List<String> testClasspath = consumer.loadLines("target/test.txt");
+        assertTrue(testClasspath.contains("test-jar-1.0-tests.jar"), testClasspath.toString());
+        assertTrue(testClasspath.contains("support-1.0.jar"), testClasspath.toString());
+
+        Verifier regularConsumer = newVerifier(testDir.resolve("regular-consumer"));
+        regularConsumer.setAutoclean(false);
+        regularConsumer.addCliArgument("validate");
+        regularConsumer.execute();
+        regularConsumer.verifyErrorFreeLog();
+
+        List<String> regularTestClasspath = regularConsumer.loadLines("target/test.txt");
+        assertTrue(regularTestClasspath.contains("test-jar-1.0.jar"), regularTestClasspath.toString());
+        assertFalse(regularTestClasspath.contains("support-1.0.jar"), regularTestClasspath.toString());
+    }
+}

its/core-it-suite/src/test/resources/mng-1378/consumer/pom.xml

@@ -0,0 +1,61 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>org.apache.maven.its.mng1378</groupId>
+  <artifactId>consumer</artifactId>
+  <version>1.0</version>
+
+  <name>Maven Integration Test :: MNG-1378 :: Test JAR Consumer</name>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.apache.maven.its.mng1378</groupId>
+      <artifactId>test-jar</artifactId>
+      <version>1.0</version>
+      <type>test-jar</type>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.its.plugins</groupId>
+        <artifactId>maven-it-plugin-dependency-resolution</artifactId>
+        <version>2.1-SNAPSHOT</version>
+        <executions>
+          <execution>
+            <id>test</id>
+            <goals>
+              <goal>test</goal>
+            </goals>
+            <phase>validate</phase>
+            <configuration>
+              <testClassPath>target/test.txt</testClassPath>
+              <significantPathLevels>1</significantPathLevels>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>

its/core-it-suite/src/test/resources/mng-1378/pom.xml

@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>org.apache.maven.its.mng1378</groupId>
+  <artifactId>parent</artifactId>
+  <version>1.0</version>
+  <packaging>pom</packaging>
+
+  <name>Maven Integration Test :: MNG-1378</name>
+  <description>Verify that dependencies required by a producer's test JAR are transitively available to test-JAR consumers.</description>
+
+  <modules>
+    <module>support</module>
+    <module>test-jar</module>
+    <module>consumer</module>
+    <module>regular-consumer</module>
+  </modules>
+</project>

its/core-it-suite/src/test/resources/mng-1378/regular-consumer/pom.xml

@@ -0,0 +1,60 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>org.apache.maven.its.mng1378</groupId>
+  <artifactId>regular-consumer</artifactId>
+  <version>1.0</version>
+
+  <name>Maven Integration Test :: MNG-1378 :: Regular JAR Consumer</name>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.apache.maven.its.mng1378</groupId>
+      <artifactId>test-jar</artifactId>
+      <version>1.0</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.its.plugins</groupId>
+        <artifactId>maven-it-plugin-dependency-resolution</artifactId>
+        <version>2.1-SNAPSHOT</version>
+        <executions>
+          <execution>
+            <id>test</id>
+            <goals>
+              <goal>test</goal>
+            </goals>
+            <phase>validate</phase>
+            <configuration>
+              <testClassPath>target/test.txt</testClassPath>
+              <significantPathLevels>1</significantPathLevels>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>

its/core-it-suite/src/test/resources/mng-1378/support/pom.xml

@@ -0,0 +1,51 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>org.apache.maven.its.mng1378</groupId>
+  <artifactId>support</artifactId>
+  <version>1.0</version>
+
+  <name>Maven Integration Test :: MNG-1378 :: Test Support</name>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.its.plugins</groupId>
+        <artifactId>maven-it-plugin-artifact</artifactId>
+        <version>2.1-SNAPSHOT</version>
+        <configuration>
+          <mainFile>pom.xml</mainFile>
+        </configuration>
+        <executions>
+          <execution>
+            <id>install</id>
+            <goals>
+              <goal>set</goal>
+              <goal>install</goal>
+            </goals>
+            <phase>validate</phase>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>