jdk/test/java/lang/ModuleLayer/BasicLayerTest.java
changeset 44545 83b611b88ac8
child 45652 33342314ce89
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/lang/ModuleLayer/BasicLayerTest.java	Fri Apr 07 08:05:54 2017 +0000
@@ -0,0 +1,1213 @@
+/*
+ * Copyright (c) 2014, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * @test
+ * @library /lib/testlibrary
+ * @modules java.base/jdk.internal.misc
+ * @build BasicLayerTest ModuleUtils
+ * @compile layertest/Test.java
+ * @run testng BasicLayerTest
+ * @summary Basic tests for java.lang.ModuleLayer
+ */
+
+import java.lang.module.Configuration;
+import java.lang.module.ModuleDescriptor;
+import java.lang.module.ModuleDescriptor.Requires;
+import java.lang.module.ModuleFinder;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import jdk.internal.misc.SharedSecrets;
+
+import org.testng.annotations.DataProvider;
+import org.testng.annotations.Test;
+import static org.testng.Assert.*;
+
+@Test
+public class BasicLayerTest {
+
+    /**
+     * Creates a "non-strict" builder for building a module. This allows the
+     * test the create ModuleDescriptor objects that do not require java.base.
+     */
+    private static ModuleDescriptor.Builder newBuilder(String mn) {
+        return SharedSecrets.getJavaLangModuleAccess()
+                .newModuleBuilder(mn, false, Set.of());
+    }
+
+    /**
+     * Exercise ModuleLayer.empty()
+     */
+    public void testEmpty() {
+        ModuleLayer emptyLayer = ModuleLayer.empty();
+
+        assertTrue(emptyLayer.parents().isEmpty());
+
+        assertTrue(emptyLayer.configuration() == Configuration.empty());
+
+        assertTrue(emptyLayer.modules().isEmpty());
+
+        assertFalse(emptyLayer.findModule("java.base").isPresent());
+
+        try {
+            emptyLayer.findLoader("java.base");
+            assertTrue(false);
+        } catch (IllegalArgumentException expected) { }
+    }
+
+
+    /**
+     * Exercise ModuleLayer.boot()
+     */
+    public void testBoot() {
+        ModuleLayer bootLayer = ModuleLayer.boot();
+
+        // configuration
+        Configuration cf = bootLayer.configuration();
+        assertTrue(cf.findModule("java.base").get()
+                .reference()
+                .descriptor()
+                .exports()
+                .stream().anyMatch(e -> (e.source().equals("java.lang")
+                                         && !e.isQualified())));
+
+        // modules
+        Set<Module> modules = bootLayer.modules();
+        assertTrue(modules.contains(Object.class.getModule()));
+        int count = (int) modules.stream().map(Module::getName).count();
+        assertEquals(count, modules.size()); // module names are unique
+
+        // findModule
+        Module base = Object.class.getModule();
+        assertTrue(bootLayer.findModule("java.base").get() == base);
+        assertTrue(base.getLayer() == bootLayer);
+
+        // findLoader
+        assertTrue(bootLayer.findLoader("java.base") == null);
+
+        // parents
+        assertTrue(bootLayer.parents().size() == 1);
+        assertTrue(bootLayer.parents().get(0) == ModuleLayer.empty());
+    }
+
+
+    /**
+     * Exercise defineModules, created with empty layer as parent
+     */
+    public void testLayerOnEmpty() {
+        ModuleDescriptor descriptor1 = newBuilder("m1")
+                .requires("m2")
+                .exports("p1")
+                .build();
+
+        ModuleDescriptor descriptor2 = newBuilder("m2")
+                .requires("m3")
+                .build();
+
+        ModuleDescriptor descriptor3 = newBuilder("m3")
+                .build();
+
+        ModuleFinder finder
+            = ModuleUtils.finderOf(descriptor1, descriptor2, descriptor3);
+
+        Configuration cf = resolve(finder, "m1");
+
+        // map each module to its own class loader for this test
+        ClassLoader loader1 = new ClassLoader() { };
+        ClassLoader loader2 = new ClassLoader() { };
+        ClassLoader loader3 = new ClassLoader() { };
+        Map<String, ClassLoader> map = new HashMap<>();
+        map.put("m1", loader1);
+        map.put("m2", loader2);
+        map.put("m3", loader3);
+
+        ModuleLayer layer = ModuleLayer.empty().defineModules(cf, map::get);
+
+        // configuration
+        assertTrue(layer.configuration() == cf);
+        assertTrue(layer.configuration().modules().size() == 3);
+
+        // modules
+        Set<Module> modules = layer.modules();
+        assertTrue(modules.size() == 3);
+        Set<String> names = modules.stream()
+            .map(Module::getName)
+            .collect(Collectors.toSet());
+        assertTrue(names.contains("m1"));
+        assertTrue(names.contains("m2"));
+        assertTrue(names.contains("m3"));
+
+        // findModule
+        Module m1 = layer.findModule("m1").get();
+        Module m2 = layer.findModule("m2").get();
+        Module m3 = layer.findModule("m3").get();
+        assertEquals(m1.getName(), "m1");
+        assertEquals(m2.getName(), "m2");
+        assertEquals(m3.getName(), "m3");
+        assertTrue(m1.getDescriptor() == descriptor1);
+        assertTrue(m2.getDescriptor() == descriptor2);
+        assertTrue(m3.getDescriptor() == descriptor3);
+        assertTrue(m1.getLayer() == layer);
+        assertTrue(m2.getLayer() == layer);
+        assertTrue(m3.getLayer() == layer);
+        assertTrue(modules.contains(m1));
+        assertTrue(modules.contains(m2));
+        assertTrue(modules.contains(m3));
+        assertFalse(layer.findModule("godot").isPresent());
+
+        // findLoader
+        assertTrue(layer.findLoader("m1") == loader1);
+        assertTrue(layer.findLoader("m2") == loader2);
+        assertTrue(layer.findLoader("m3") == loader3);
+        try {
+            ClassLoader loader = layer.findLoader("godot");
+            assertTrue(false);
+        } catch (IllegalArgumentException ignore) { }
+
+        // parents
+        assertTrue(layer.parents().size() == 1);
+        assertTrue(layer.parents().get(0) == ModuleLayer.empty());
+    }
+
+
+    /**
+     * Exercise defineModules, created with boot layer as parent
+     */
+    public void testLayerOnBoot() {
+        ModuleDescriptor descriptor1 = newBuilder("m1")
+                .requires("m2")
+                .requires("java.base")
+                .exports("p1")
+                .build();
+
+        ModuleDescriptor descriptor2 = newBuilder("m2")
+                .requires("java.base")
+                .build();
+
+        ModuleFinder finder
+            = ModuleUtils.finderOf(descriptor1, descriptor2);
+
+        Configuration parent = ModuleLayer.boot().configuration();
+        Configuration cf = resolve(parent, finder, "m1");
+
+        ClassLoader loader = new ClassLoader() { };
+
+        ModuleLayer layer = ModuleLayer.boot().defineModules(cf, mn -> loader);
+
+        // configuration
+        assertTrue(layer.configuration() == cf);
+        assertTrue(layer.configuration().modules().size() == 2);
+
+        // modules
+        Set<Module> modules = layer.modules();
+        assertTrue(modules.size() == 2);
+        Set<String> names = modules.stream()
+            .map(Module::getName)
+            .collect(Collectors.toSet());
+        assertTrue(names.contains("m1"));
+        assertTrue(names.contains("m2"));
+
+        // findModule
+        Module m1 = layer.findModule("m1").get();
+        Module m2 = layer.findModule("m2").get();
+        assertEquals(m1.getName(), "m1");
+        assertEquals(m2.getName(), "m2");
+        assertTrue(m1.getDescriptor() == descriptor1);
+        assertTrue(m2.getDescriptor() == descriptor2);
+        assertTrue(m1.getLayer() == layer);
+        assertTrue(m2.getLayer() == layer);
+        assertTrue(modules.contains(m1));
+        assertTrue(modules.contains(m2));
+        assertTrue(layer.findModule("java.base").get() == Object.class.getModule());
+        assertFalse(layer.findModule("godot").isPresent());
+
+        // findLoader
+        assertTrue(layer.findLoader("m1") == loader);
+        assertTrue(layer.findLoader("m2") == loader);
+        assertTrue(layer.findLoader("java.base") == null);
+
+        // parents
+        assertTrue(layer.parents().size() == 1);
+        assertTrue(layer.parents().get(0) == ModuleLayer.boot());
+    }
+
+
+    /**
+     * Exercise defineModules with a configuration of two modules that
+     * have the same module-private package.
+     */
+    public void testPackageContainedInSelfAndOther() {
+        ModuleDescriptor descriptor1 =  newBuilder("m1")
+                .requires("m2")
+                .packages(Set.of("p"))
+                .build();
+
+        ModuleDescriptor descriptor2 = newBuilder("m2")
+                .packages(Set.of("p"))
+                .build();
+
+        ModuleFinder finder
+            = ModuleUtils.finderOf(descriptor1, descriptor2);
+
+        Configuration cf = resolve(finder, "m1");
+        assertTrue(cf.modules().size() == 2);
+
+        // one loader per module, should be okay
+        ModuleLayer.empty().defineModules(cf, mn -> new ClassLoader() { });
+
+        // same class loader
+        try {
+            ClassLoader loader = new ClassLoader() { };
+            ModuleLayer.empty().defineModules(cf, mn -> loader);
+            assertTrue(false);
+        } catch (LayerInstantiationException expected) { }
+    }
+
+
+    /**
+     * Exercise defineModules with a configuration that is a partitioned
+     * graph. The same package is exported in both partitions.
+     */
+    public void testSameExportInPartitionedGraph() {
+
+        // m1 reads m2, m2 exports p to m1
+        ModuleDescriptor descriptor1 =  newBuilder("m1")
+                .requires("m2")
+                .build();
+        ModuleDescriptor descriptor2 =  newBuilder("m2")
+                .exports("p", Set.of("m1"))
+                .build();
+
+        // m3 reads m4, m4 exports p to m3
+        ModuleDescriptor descriptor3 = newBuilder("m3")
+                .requires("m4")
+                .build();
+        ModuleDescriptor descriptor4 = newBuilder("m4")
+                .exports("p", Set.of("m3"))
+                .build();
+
+        ModuleFinder finder
+            = ModuleUtils.finderOf(descriptor1,
+                                   descriptor2,
+                                   descriptor3,
+                                   descriptor4);
+
+        Configuration cf = resolve(finder, "m1", "m3");
+        assertTrue(cf.modules().size() == 4);
+
+        // one loader per module
+        ModuleLayer.empty().defineModules(cf, mn -> new ClassLoader() { });
+
+        // m1 & m2 in one loader, m3 & m4 in another loader
+        ClassLoader loader1 = new ClassLoader() { };
+        ClassLoader loader2 = new ClassLoader() { };
+        Map<String, ClassLoader> map = new HashMap<>();
+        map.put("m1", loader1);
+        map.put("m2", loader1);
+        map.put("m3", loader2);
+        map.put("m4", loader2);
+        ModuleLayer.empty().defineModules(cf, map::get);
+
+        // same loader
+        try {
+            ClassLoader loader = new ClassLoader() { };
+            ModuleLayer.empty().defineModules(cf, mn -> loader);
+            assertTrue(false);
+        } catch (LayerInstantiationException expected) { }
+    }
+
+
+    /**
+     * Exercise defineModules with a configuration with a module that
+     * contains a package that is the same name as a non-exported package in
+     * a parent layer.
+     */
+    public void testContainsSamePackageAsBootLayer() {
+
+        // check assumption that java.base contains sun.launcher
+        ModuleDescriptor base = Object.class.getModule().getDescriptor();
+        assertTrue(base.packages().contains("sun.launcher"));
+
+        ModuleDescriptor descriptor = newBuilder("m1")
+               .requires("java.base")
+               .packages(Set.of("sun.launcher"))
+               .build();
+
+        ModuleFinder finder = ModuleUtils.finderOf(descriptor);
+
+        Configuration parent = ModuleLayer.boot().configuration();
+        Configuration cf = parent.resolve(finder, ModuleFinder.of(), Set.of("m1"));
+        assertTrue(cf.modules().size() == 1);
+
+        ClassLoader loader = new ClassLoader() { };
+        ModuleLayer layer = ModuleLayer.boot().defineModules(cf, mn -> loader);
+        assertTrue(layer.modules().size() == 1);
+   }
+
+
+    /**
+     * Test layers with implied readability.
+     *
+     * The test consists of three configurations:
+     * - Configuration/layer1: m1, m2 requires transitive m1
+     * - Configuration/layer2: m3 requires m1
+     */
+    public void testImpliedReadabilityWithLayers1() {
+
+        // cf1: m1 and m2, m2 requires transitive m1
+
+        ModuleDescriptor descriptor1 = newBuilder("m1")
+                .build();
+
+        ModuleDescriptor descriptor2 = newBuilder("m2")
+                .requires(Set.of(Requires.Modifier.TRANSITIVE), "m1")
+                .build();
+
+        ModuleFinder finder1 = ModuleUtils.finderOf(descriptor1, descriptor2);
+
+        Configuration cf1 = resolve(finder1, "m2");
+
+        ClassLoader cl1 = new ClassLoader() { };
+        ModuleLayer layer1 = ModuleLayer.empty().defineModules(cf1, mn -> cl1);
+
+
+        // cf2: m3, m3 requires m2
+
+        ModuleDescriptor descriptor3 = newBuilder("m3")
+                .requires("m2")
+                .build();
+
+        ModuleFinder finder2 = ModuleUtils.finderOf(descriptor3);
+
+        Configuration cf2 = resolve(cf1, finder2, "m3");
+
+        ClassLoader cl2 = new ClassLoader() { };
+        ModuleLayer layer2 = layer1.defineModules(cf2, mn -> cl2);
+
+        assertTrue(layer1.parents().size() == 1);
+        assertTrue(layer1.parents().get(0) == ModuleLayer.empty());
+
+        assertTrue(layer2.parents().size() == 1);
+        assertTrue(layer2.parents().get(0) == layer1);
+
+        Module m1 = layer2.findModule("m1").get();
+        Module m2 = layer2.findModule("m2").get();
+        Module m3 = layer2.findModule("m3").get();
+
+        assertTrue(m1.getLayer() == layer1);
+        assertTrue(m2.getLayer() == layer1);
+        assertTrue(m3.getLayer() == layer2);
+
+        assertTrue(m1.getClassLoader() == cl1);
+        assertTrue(m2.getClassLoader() == cl1);
+        assertTrue(m3.getClassLoader() == cl2);
+
+        assertTrue(m1.canRead(m1));
+        assertFalse(m1.canRead(m2));
+        assertFalse(m1.canRead(m3));
+
+        assertTrue(m2.canRead(m1));
+        assertTrue(m2.canRead(m2));
+        assertFalse(m2.canRead(m3));
+
+        assertTrue(m3.canRead(m1));
+        assertTrue(m3.canRead(m2));
+        assertTrue(m3.canRead(m3));
+    }
+
+
+    /**
+     * Test layers with implied readability.
+     *
+     * The test consists of three configurations:
+     * - Configuration/layer1: m1
+     * - Configuration/layer2: m2 requires transitive m3, m3 requires m2
+     */
+    public void testImpliedReadabilityWithLayers2() {
+
+        // cf1: m1
+
+        ModuleDescriptor descriptor1 = newBuilder("m1").build();
+
+        ModuleFinder finder1 = ModuleUtils.finderOf(descriptor1);
+
+        Configuration cf1 = resolve(finder1, "m1");
+
+        ClassLoader cl1 = new ClassLoader() { };
+        ModuleLayer layer1 = ModuleLayer.empty().defineModules(cf1, mn -> cl1);
+
+
+        // cf2: m2, m3: m2 requires transitive m1, m3 requires m2
+
+        ModuleDescriptor descriptor2 = newBuilder("m2")
+                .requires(Set.of(Requires.Modifier.TRANSITIVE), "m1")
+                .build();
+
+        ModuleDescriptor descriptor3 = newBuilder("m3")
+                .requires("m2")
+                .build();
+
+        ModuleFinder finder2 = ModuleUtils.finderOf(descriptor2, descriptor3);
+
+        Configuration cf2 = resolve(cf1, finder2, "m3");
+
+        ClassLoader cl2 = new ClassLoader() { };
+        ModuleLayer layer2 = layer1.defineModules(cf2, mn -> cl2);
+
+        assertTrue(layer1.parents().size() == 1);
+        assertTrue(layer1.parents().get(0) == ModuleLayer.empty());
+
+        assertTrue(layer2.parents().size() == 1);
+        assertTrue(layer2.parents().get(0) == layer1);
+
+        Module m1 = layer2.findModule("m1").get();
+        Module m2 = layer2.findModule("m2").get();
+        Module m3 = layer2.findModule("m3").get();
+
+        assertTrue(m1.getLayer() == layer1);
+        assertTrue(m2.getLayer() == layer2);
+        assertTrue(m3.getLayer() == layer2);
+
+        assertTrue(m1.canRead(m1));
+        assertFalse(m1.canRead(m2));
+        assertFalse(m1.canRead(m3));
+
+        assertTrue(m2.canRead(m1));
+        assertTrue(m2.canRead(m2));
+        assertFalse(m2.canRead(m3));
+
+        assertTrue(m3.canRead(m1));
+        assertTrue(m3.canRead(m2));
+        assertTrue(m3.canRead(m3));
+    }
+
+
+    /**
+     * Test layers with implied readability.
+     *
+     * The test consists of three configurations:
+     * - Configuration/layer1: m1
+     * - Configuration/layer2: m2 requires transitive m1
+     * - Configuration/layer3: m3 requires m1
+     */
+    public void testImpliedReadabilityWithLayers3() {
+
+        // cf1: m1
+
+        ModuleDescriptor descriptor1 = newBuilder("m1").build();
+
+        ModuleFinder finder1 = ModuleUtils.finderOf(descriptor1);
+
+        Configuration cf1 = resolve(finder1, "m1");
+
+        ClassLoader cl1 = new ClassLoader() { };
+        ModuleLayer layer1 = ModuleLayer.empty().defineModules(cf1, mn -> cl1);
+
+
+        // cf2: m2 requires transitive m1
+
+        ModuleDescriptor descriptor2 = newBuilder("m2")
+                .requires(Set.of(Requires.Modifier.TRANSITIVE), "m1")
+                .build();
+
+        ModuleFinder finder2 = ModuleUtils.finderOf(descriptor2);
+
+        Configuration cf2 = resolve(cf1, finder2, "m2");
+
+        ClassLoader cl2 = new ClassLoader() { };
+        ModuleLayer layer2 = layer1.defineModules(cf2, mn -> cl2);
+
+
+        // cf3: m3 requires m2
+
+        ModuleDescriptor descriptor3 = newBuilder("m3")
+                .requires("m2")
+                .build();
+
+        ModuleFinder finder3 = ModuleUtils.finderOf(descriptor3);
+
+        Configuration cf3 = resolve(cf2, finder3, "m3");
+
+        ClassLoader cl3 = new ClassLoader() { };
+        ModuleLayer layer3 = layer2.defineModules(cf3, mn -> cl3);
+
+        assertTrue(layer1.parents().size() == 1);
+        assertTrue(layer1.parents().get(0) == ModuleLayer.empty());
+
+        assertTrue(layer2.parents().size() == 1);
+        assertTrue(layer2.parents().get(0) == layer1);
+
+        assertTrue(layer3.parents().size() == 1);
+        assertTrue(layer3.parents().get(0) == layer2);
+
+        Module m1 = layer3.findModule("m1").get();
+        Module m2 = layer3.findModule("m2").get();
+        Module m3 = layer3.findModule("m3").get();
+
+        assertTrue(m1.getLayer() == layer1);
+        assertTrue(m2.getLayer() == layer2);
+        assertTrue(m3.getLayer() == layer3);
+
+        assertTrue(m1.canRead(m1));
+        assertFalse(m1.canRead(m2));
+        assertFalse(m1.canRead(m3));
+
+        assertTrue(m2.canRead(m1));
+        assertTrue(m2.canRead(m2));
+        assertFalse(m2.canRead(m3));
+
+        assertTrue(m3.canRead(m1));
+        assertTrue(m3.canRead(m2));
+        assertTrue(m3.canRead(m3));
+    }
+
+
+    /**
+     * Test layers with implied readability.
+     *
+     * The test consists of two configurations:
+     * - Configuration/layer1: m1, m2 requires transitive m1
+     * - Configuration/layer2: m3 requires transitive m2, m4 requires m3
+     */
+    public void testImpliedReadabilityWithLayers4() {
+
+        // cf1: m1, m2 requires transitive m1
+
+        ModuleDescriptor descriptor1 = newBuilder("m1")
+                .build();
+
+        ModuleDescriptor descriptor2 = newBuilder("m2")
+                .requires(Set.of(Requires.Modifier.TRANSITIVE), "m1")
+                .build();
+
+        ModuleFinder finder1 = ModuleUtils.finderOf(descriptor1, descriptor2);
+
+        Configuration cf1 = resolve(finder1, "m2");
+
+        ClassLoader cl1 = new ClassLoader() { };
+        ModuleLayer layer1 = ModuleLayer.empty().defineModules(cf1, mn -> cl1);
+
+
+        // cf2: m3 requires transitive m2, m4 requires m3
+
+        ModuleDescriptor descriptor3 = newBuilder("m3")
+                .requires(Set.of(Requires.Modifier.TRANSITIVE), "m2")
+                .build();
+
+        ModuleDescriptor descriptor4 = newBuilder("m4")
+                .requires("m3")
+                .build();
+
+
+        ModuleFinder finder2 = ModuleUtils.finderOf(descriptor3, descriptor4);
+
+        Configuration cf2 = resolve(cf1, finder2, "m3", "m4");
+
+        ClassLoader cl2 = new ClassLoader() { };
+        ModuleLayer layer2 = layer1.defineModules(cf2, mn -> cl2);
+
+        assertTrue(layer1.parents().size() == 1);
+        assertTrue(layer1.parents().get(0) == ModuleLayer.empty());
+
+        assertTrue(layer2.parents().size() == 1);
+        assertTrue(layer2.parents().get(0) == layer1);
+
+        Module m1 = layer2.findModule("m1").get();
+        Module m2 = layer2.findModule("m2").get();
+        Module m3 = layer2.findModule("m3").get();
+        Module m4 = layer2.findModule("m4").get();
+
+        assertTrue(m1.getLayer() == layer1);
+        assertTrue(m2.getLayer() == layer1);
+        assertTrue(m3.getLayer() == layer2);
+        assertTrue(m4.getLayer() == layer2);
+
+        assertTrue(m1.canRead(m1));
+        assertFalse(m1.canRead(m2));
+        assertFalse(m1.canRead(m3));
+        assertFalse(m1.canRead(m4));
+
+        assertTrue(m2.canRead(m1));
+        assertTrue(m2.canRead(m2));
+        assertFalse(m1.canRead(m3));
+        assertFalse(m1.canRead(m4));
+
+        assertTrue(m3.canRead(m1));
+        assertTrue(m3.canRead(m2));
+        assertTrue(m3.canRead(m3));
+        assertFalse(m3.canRead(m4));
+
+        assertTrue(m4.canRead(m1));
+        assertTrue(m4.canRead(m2));
+        assertTrue(m4.canRead(m3));
+        assertTrue(m4.canRead(m4));
+    }
+
+
+    /**
+     * Test layers with a qualified export. The module exporting the package
+     * does not read the target module.
+     *
+     * m1 { exports p to m2 }
+     * m2 { }
+     */
+    public void testQualifiedExports1() {
+        ModuleDescriptor descriptor1 = newBuilder("m1").
+                exports("p", Set.of("m2"))
+                .build();
+
+        ModuleDescriptor descriptor2 = newBuilder("m2")
+                .build();
+
+        ModuleFinder finder1 = ModuleUtils.finderOf(descriptor1, descriptor2);
+
+        Configuration cf = resolve(finder1, "m1", "m2");
+
+        ClassLoader cl = new ClassLoader() { };
+        ModuleLayer layer = ModuleLayer.empty().defineModules(cf, mn -> cl);
+        assertTrue(layer.modules().size() == 2);
+
+        Module m1 = layer.findModule("m1").get();
+        Module m2 = layer.findModule("m2").get();
+
+        // check m1 exports p to m2
+        assertFalse(m1.isExported("p"));
+        assertTrue(m1.isExported("p", m2));
+        assertFalse(m1.isOpen("p", m2));
+    }
+
+
+    /**
+     * Test layers with a qualified export. The module exporting the package
+     * reads the target module.
+     *
+     * m1 { exports p to m2; }
+     * m2 { requires m1; }
+     */
+    public void testQualifiedExports2() {
+        ModuleDescriptor descriptor1 = newBuilder("m1")
+                .exports("p", Set.of("m2"))
+                .build();
+
+        ModuleDescriptor descriptor2 = newBuilder("m2")
+                .requires("m1")
+                .build();
+
+        ModuleFinder finder1 = ModuleUtils.finderOf(descriptor1, descriptor2);
+
+        Configuration cf = resolve(finder1, "m2");
+        ClassLoader cl = new ClassLoader() { };
+        ModuleLayer layer = ModuleLayer.empty().defineModules(cf, mn -> cl);
+        assertTrue(layer.modules().size() == 2);
+
+        Module m1 = layer.findModule("m1").get();
+        Module m2 = layer.findModule("m2").get();
+
+        // check m1 exports p to m2
+        assertFalse(m1.isExported("p"));
+        assertTrue(m1.isExported("p", m2));
+        assertFalse(m1.isOpen("p", m2));
+    }
+
+
+    /**
+     * Test layers with a qualified export. The module exporting the package
+     * does not read the target module in the parent layer.
+     *
+     * - Configuration/layer1: m1 { }
+     * - Configuration/layer2: m2 { exports p to m1; }
+     */
+    public void testQualifiedExports3() {
+        // create layer1 with m1
+        ModuleDescriptor descriptor1 = newBuilder("m1").build();
+        ModuleFinder finder1 = ModuleUtils.finderOf(descriptor1);
+        Configuration cf1 = resolve(finder1, "m1");
+        ClassLoader cl1 = new ClassLoader() { };
+        ModuleLayer layer1 = ModuleLayer.empty().defineModules(cf1, mn -> cl1);
+        assertTrue(layer1.modules().size() == 1);
+
+        // create layer2 with m2
+        ModuleDescriptor descriptor2 = newBuilder("m2")
+                .exports("p", Set.of("m1"))
+                .build();
+        ModuleFinder finder2 = ModuleUtils.finderOf(descriptor2);
+        Configuration cf2 = resolve(cf1, finder2, "m2");
+        ClassLoader cl2 = new ClassLoader() { };
+        ModuleLayer layer2 = layer1.defineModules(cf2, mn -> cl2);
+        assertTrue(layer2.modules().size() == 1);
+
+        Module m1 = layer1.findModule("m1").get();
+        Module m2 = layer2.findModule("m2").get();
+
+        // check m2 exports p to layer1/m1
+        assertFalse(m2.isExported("p"));
+        assertTrue(m2.isExported("p", m1));
+        assertFalse(m2.isOpen("p", m1));
+    }
+
+
+    /**
+     * Test layers with a qualified export. The module exporting the package
+     * reads the target module in the parent layer.
+     *
+     * - Configuration/layer1: m1 { }
+     * - Configuration/layer2: m2 { requires m1; exports p to m1; }
+     */
+    public void testQualifiedExports4() {
+        // create layer1 with m1
+        ModuleDescriptor descriptor1 = newBuilder("m1").build();
+        ModuleFinder finder1 = ModuleUtils.finderOf(descriptor1);
+        Configuration cf1 = resolve(finder1, "m1");
+        ClassLoader cl1 = new ClassLoader() { };
+        ModuleLayer layer1 = ModuleLayer.empty().defineModules(cf1, mn -> cl1);
+        assertTrue(layer1.modules().size() == 1);
+
+        // create layer2 with m2
+        ModuleDescriptor descriptor2 = newBuilder("m2")
+                .requires("m1")
+                .exports("p", Set.of("m1"))
+                .build();
+        ModuleFinder finder2 = ModuleUtils.finderOf(descriptor2);
+        Configuration cf2 = resolve(cf1, finder2, "m2");
+        ClassLoader cl2 = new ClassLoader() { };
+        ModuleLayer layer2 = layer1.defineModules(cf2, mn -> cl2);
+        assertTrue(layer2.modules().size() == 1);
+
+        Module m1 = layer1.findModule("m1").get();
+        Module m2 = layer2.findModule("m2").get();
+
+        // check m2 exports p to layer1/m1
+        assertFalse(m2.isExported("p"));
+        assertTrue(m2.isExported("p", m1));
+        assertFalse(m2.isOpen("p", m1));
+    }
+
+    /**
+     * Test layers with a qualified export. The module exporting the package
+     * does not read the target module.
+     *
+     * - Configuration/layer1: m1
+     * - Configuration/layer2: m1, m2 { exports p to m1; }
+     */
+    public void testQualifiedExports5() {
+        // create layer1 with m1
+        ModuleDescriptor descriptor1 = newBuilder("m1").build();
+        ModuleFinder finder1 = ModuleUtils.finderOf(descriptor1);
+        Configuration cf1 = resolve(finder1, "m1");
+        ClassLoader cl1 = new ClassLoader() { };
+        ModuleLayer layer1 = ModuleLayer.empty().defineModules(cf1, mn -> cl1);
+        assertTrue(layer1.modules().size() == 1);
+
+        // create layer2 with m1 and m2
+        ModuleDescriptor descriptor2 = newBuilder("m2").exports("p", Set.of("m1")).build();
+        ModuleFinder finder2 = ModuleUtils.finderOf(descriptor1, descriptor2);
+        Configuration cf2 = resolve(cf1, finder2, "m1", "m2");
+        ClassLoader cl2 = new ClassLoader() { };
+        ModuleLayer layer2 = layer1.defineModules(cf2, mn -> cl2);
+        assertTrue(layer2.modules().size() == 2);
+
+        Module m1_v1 = layer1.findModule("m1").get();
+        Module m1_v2 = layer2.findModule("m1").get();
+        Module m2 = layer2.findModule("m2").get();
+
+        // check m2 exports p to layer2/m2
+        assertFalse(m2.isExported("p"));
+        assertTrue(m2.isExported("p", m1_v2));
+        assertFalse(m2.isExported("p", m1_v1));
+    }
+
+
+    /**
+     * Test layers with a qualified export. The module exporting the package
+     * reads the target module in the parent layer (due to requires transitive).
+     *
+     * - Configuration/layer1: m1, m2 { requires transitive m1; }
+     * - Configuration/layer2: m1, m3 { requires m2; exports p to m1; }
+     */
+    public void testQualifiedExports6() {
+        // create layer1 with m1 and m2
+        ModuleDescriptor descriptor1 = newBuilder("m1").build();
+        ModuleDescriptor descriptor2 = newBuilder("m2")
+                .requires(Set.of(Requires.Modifier.TRANSITIVE), "m1")
+                .build();
+        ModuleFinder finder1 = ModuleUtils.finderOf(descriptor1, descriptor2);
+        Configuration cf1 = resolve(finder1, "m2");
+        ClassLoader loader1 = new ClassLoader() { };
+        ModuleLayer layer1 = ModuleLayer.empty().defineModules(cf1, mn -> loader1);
+        assertTrue(layer1.modules().size() == 2);
+
+        // create layer2 with m1 and m3
+        ModuleDescriptor descriptor3 = newBuilder("m3")
+                .requires("m2")
+                .exports("p", Set.of("m1"))
+                .build();
+        ModuleFinder finder2 = ModuleUtils.finderOf(descriptor1, descriptor3);
+        Configuration cf2 = resolve(cf1, finder2, "m1", "m3");
+        ClassLoader loader2 = new ClassLoader() { };
+        ModuleLayer layer2 = layer1.defineModules(cf2, mn -> loader2);
+        assertTrue(layer2.modules().size() == 2);
+
+        Module m1_v1 = layer1.findModule("m1").get();
+        Module m2 = layer1.findModule("m2").get();
+
+        Module m1_v2 = layer2.findModule("m1").get();
+        Module m3 = layer2.findModule("m3").get();
+
+        assertTrue(m3.canRead(m1_v1));
+        assertFalse(m3.canRead(m1_v2));
+
+        assertFalse(m3.isExported("p"));
+        assertTrue(m3.isExported("p", m1_v1));
+        assertFalse(m3.isExported("p", m1_v2));
+        assertFalse(m3.isExported("p", m2));
+    }
+
+
+    /**
+     * Test layers with a qualified export. The target module is not in any layer.
+     *
+     * - Configuration/layer1: m1 { }
+     * - Configuration/layer2: m2 { exports p to m3; }
+     */
+    public void testQualifiedExports7() {
+        // create layer1 with m1
+        ModuleDescriptor descriptor1 = newBuilder("m1").build();
+        ModuleFinder finder1 = ModuleUtils.finderOf(descriptor1);
+        Configuration cf1 = resolve(finder1, "m1");
+        ClassLoader cl1 = new ClassLoader() { };
+        ModuleLayer layer1 = ModuleLayer.empty().defineModules(cf1, mn -> cl1);
+        assertTrue(layer1.modules().size() == 1);
+
+        // create layer2 with m2
+        ModuleDescriptor descriptor2 = newBuilder("m2")
+                .exports("p", Set.of("m3"))
+                .build();
+        ModuleFinder finder2 = ModuleUtils.finderOf(descriptor2);
+        Configuration cf2 = resolve(cf1, finder2, "m2");
+        ClassLoader cl2 = new ClassLoader() { };
+        ModuleLayer layer2 = layer1.defineModules(cf2, mn -> cl2);
+        assertTrue(layer2.modules().size() == 1);
+
+        Module m1 = layer1.findModule("m1").get();
+        Module m2 = layer2.findModule("m2").get();
+
+        // check m2 does not export p to anyone
+        assertFalse(m2.isExported("p"));
+        assertFalse(m2.isExported("p", m1));
+    }
+
+    /**
+     * Attempt to use defineModules to create a layer with a module defined
+     * to a class loader that already has a module of the same name defined
+     * to the class loader.
+     */
+    @Test(expectedExceptions = { LayerInstantiationException.class })
+    public void testModuleAlreadyDefinedToLoader() {
+
+        ModuleDescriptor md = newBuilder("m")
+                .requires("java.base")
+                .build();
+
+        ModuleFinder finder = ModuleUtils.finderOf(md);
+
+        Configuration parent = ModuleLayer.boot().configuration();
+
+        Configuration cf = parent.resolve(finder, ModuleFinder.of(), Set.of("m"));
+
+        ClassLoader loader = new ClassLoader() { };
+
+        ModuleLayer.boot().defineModules(cf, mn -> loader);
+
+        // should throw LayerInstantiationException as m1 already defined to loader
+        ModuleLayer.boot().defineModules(cf, mn -> loader);
+
+    }
+
+
+    /**
+     * Attempt to use defineModules to create a layer with a module containing
+     * package {@code p} where the class loader already has a module defined
+     * to it containing package {@code p}.
+     */
+    @Test(expectedExceptions = { LayerInstantiationException.class })
+    public void testPackageAlreadyInNamedModule() {
+
+        ModuleDescriptor md1 = newBuilder("m1")
+                .packages(Set.of("p"))
+                .requires("java.base")
+                .build();
+
+        ModuleDescriptor md2 = newBuilder("m2")
+                .packages(Set.of("p"))
+                .requires("java.base")
+                .build();
+
+        ModuleFinder finder = ModuleUtils.finderOf(md1, md2);
+
+        ClassLoader loader = new ClassLoader() { };
+
+        // define m1 containing package p to class loader
+
+        Configuration parent = ModuleLayer.boot().configuration();
+
+        Configuration cf1 = parent.resolve(finder, ModuleFinder.of(), Set.of("m1"));
+
+        ModuleLayer layer1 = ModuleLayer.boot().defineModules(cf1, mn -> loader);
+
+        // attempt to define m2 containing package p to class loader
+
+        Configuration cf2 = parent.resolve(finder, ModuleFinder.of(), Set.of("m2"));
+
+        // should throw exception because p already in m1
+        ModuleLayer layer2 = ModuleLayer.boot().defineModules(cf2, mn -> loader);
+
+    }
+
+
+    /**
+     * Attempt to use defineModules to create a layer with a module
+     * containing a package in which a type is already loaded by the class
+     * loader.
+     */
+    @Test(expectedExceptions = { LayerInstantiationException.class })
+    public void testPackageAlreadyInUnnamedModule() throws Exception {
+
+        Class<?> c = layertest.Test.class;
+        assertFalse(c.getModule().isNamed());  // in unnamed module
+
+        ModuleDescriptor md = newBuilder("m")
+                .packages(Set.of(c.getPackageName()))
+                .requires("java.base")
+                .build();
+
+        ModuleFinder finder = ModuleUtils.finderOf(md);
+
+        Configuration parent = ModuleLayer.boot().configuration();
+        Configuration cf = parent.resolve(finder, ModuleFinder.of(), Set.of("m"));
+
+        ModuleLayer.boot().defineModules(cf, mn -> c.getClassLoader());
+    }
+
+
+    /**
+     * Attempt to create a layer with a module named "java.base".
+     */
+    public void testLayerWithJavaBase() {
+        ModuleDescriptor descriptor = newBuilder("java.base")
+                .exports("java.lang")
+                .build();
+
+        ModuleFinder finder = ModuleUtils.finderOf(descriptor);
+
+        Configuration cf = ModuleLayer.boot()
+            .configuration()
+            .resolve(finder, ModuleFinder.of(), Set.of("java.base"));
+        assertTrue(cf.modules().size() == 1);
+
+        ClassLoader scl = ClassLoader.getSystemClassLoader();
+
+        try {
+            ModuleLayer.boot().defineModules(cf, mn -> new ClassLoader() { });
+            assertTrue(false);
+        } catch (LayerInstantiationException e) { }
+
+        try {
+            ModuleLayer.boot().defineModulesWithOneLoader(cf, scl);
+            assertTrue(false);
+        } catch (LayerInstantiationException e) { }
+
+        try {
+            ModuleLayer.boot().defineModulesWithManyLoaders(cf, scl);
+            assertTrue(false);
+        } catch (LayerInstantiationException e) { }
+    }
+
+
+    @DataProvider(name = "javaPackages")
+    public Object[][] javaPackages() {
+        return new Object[][] { { "m1", "java" }, { "m2", "java.x" } };
+    }
+
+    /**
+     * Attempt to create a layer with a module containing a "java" package.
+     * This should only be allowed when the module is defined to the platform
+     * class loader.
+     */
+    @Test(dataProvider = "javaPackages")
+    public void testLayerWithJavaPackage(String mn, String pn) {
+        ModuleDescriptor descriptor = newBuilder(mn).packages(Set.of(pn)).build();
+        ModuleFinder finder = ModuleUtils.finderOf(descriptor);
+
+        Configuration cf = ModuleLayer.boot()
+                .configuration()
+                .resolve(finder, ModuleFinder.of(), Set.of(mn));
+        assertTrue(cf.modules().size() == 1);
+
+        ClassLoader pcl = ClassLoader.getPlatformClassLoader();
+        ClassLoader scl = ClassLoader.getSystemClassLoader();
+
+        try {
+            ModuleLayer.boot().defineModules(cf, _mn -> new ClassLoader() { });
+            assertTrue(false);
+        } catch (LayerInstantiationException e) { }
+
+        try {
+            ModuleLayer.boot().defineModulesWithOneLoader(cf, scl);
+            assertTrue(false);
+        } catch (LayerInstantiationException e) { }
+
+        try {
+            ModuleLayer.boot().defineModulesWithManyLoaders(cf, scl);
+            assertTrue(false);
+        } catch (LayerInstantiationException e) { }
+
+        // create layer with module defined to platform class loader
+        ModuleLayer layer = ModuleLayer.boot().defineModules(cf, _mn -> pcl);
+        Optional<Module> om = layer.findModule(mn);
+        assertTrue(om.isPresent());
+        Module foo = om.get();
+        assertTrue(foo.getClassLoader() == pcl);
+        assertTrue(foo.getPackages().size() == 1);
+        assertTrue(foo.getPackages().iterator().next().equals(pn));
+    }
+
+
+    /**
+     * Attempt to create a layer with a module defined to the boot loader
+     */
+    @Test(expectedExceptions = { LayerInstantiationException.class })
+    public void testLayerWithBootLoader() {
+        ModuleDescriptor descriptor = newBuilder("m1")
+                .build();
+
+        ModuleFinder finder = ModuleUtils.finderOf(descriptor);
+
+        Configuration cf = ModuleLayer.boot()
+            .configuration()
+            .resolve(finder, ModuleFinder.of(), Set.of("m1"));
+        assertTrue(cf.modules().size() == 1);
+
+        ModuleLayer.boot().defineModules(cf, mn -> null );
+    }
+
+
+    /**
+     * Parent of configuration != configuration of parent layer
+     */
+    @Test(expectedExceptions = { IllegalArgumentException.class })
+    public void testIncorrectParent1() {
+        ModuleDescriptor descriptor1 = newBuilder("m1")
+                .requires("java.base")
+                .build();
+
+        ModuleFinder finder = ModuleUtils.finderOf(descriptor1);
+
+        Configuration parent = ModuleLayer.boot().configuration();
+        Configuration cf = parent.resolve(finder, ModuleFinder.of(), Set.of("m1"));
+
+        ClassLoader loader = new ClassLoader() { };
+        ModuleLayer.empty().defineModules(cf, mn -> loader);
+    }
+
+
+    /**
+     * Parent of configuration != configuration of parent layer
+     */
+    @Test(expectedExceptions = { IllegalArgumentException.class })
+    public void testIncorrectParent2() {
+        ModuleDescriptor descriptor1 = newBuilder("m1").build();
+
+        ModuleFinder finder = ModuleUtils.finderOf(descriptor1);
+
+        Configuration cf = resolve(finder, "m1");
+
+        ClassLoader loader = new ClassLoader() { };
+        ModuleLayer.boot().defineModules(cf, mn -> loader);
+    }
+
+
+    // null handling
+
+    @Test(expectedExceptions = { NullPointerException.class })
+    public void testCreateWithNull1() {
+        ClassLoader loader = new ClassLoader() { };
+        ModuleLayer.empty().defineModules(null, mn -> loader);
+    }
+
+    @Test(expectedExceptions = { NullPointerException.class })
+    public void testCreateWithNull2() {
+        Configuration cf = resolve(ModuleLayer.boot().configuration(), ModuleFinder.of());
+        ModuleLayer.boot().defineModules(cf, null);
+    }
+
+    @Test(expectedExceptions = { NullPointerException.class })
+    public void testCreateWithNull3() {
+        ClassLoader scl = ClassLoader.getSystemClassLoader();
+        ModuleLayer.empty().defineModulesWithOneLoader(null, scl);
+    }
+
+    @Test(expectedExceptions = { NullPointerException.class })
+    public void testCreateWithNull4() {
+        ClassLoader scl = ClassLoader.getSystemClassLoader();
+        ModuleLayer.empty().defineModulesWithManyLoaders(null, scl);
+    }
+
+    @Test(expectedExceptions = { NullPointerException.class })
+    public void testFindModuleWithNull() {
+        ModuleLayer.boot().findModule(null);
+    }
+
+    @Test(expectedExceptions = { NullPointerException.class })
+    public void testFindLoaderWithNull() {
+        ModuleLayer.boot().findLoader(null);
+    }
+
+
+    // immutable sets
+
+    @Test(expectedExceptions = { UnsupportedOperationException.class })
+    public void testImmutableSet() {
+        Module base = Object.class.getModule();
+        ModuleLayer.boot().modules().add(base);
+    }
+
+
+    /**
+     * Resolve the given modules, by name, and returns the resulting
+     * Configuration.
+     */
+    private static Configuration resolve(Configuration cf,
+                                         ModuleFinder finder,
+                                         String... roots) {
+        return cf.resolve(finder, ModuleFinder.of(), Set.of(roots));
+    }
+
+    private static Configuration resolve(ModuleFinder finder,
+                                         String... roots) {
+        return resolve(Configuration.empty(), finder, roots);
+    }
+}