/* * Copyright (c) 2022, 2025, 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 * @bug 8282823 8343540 * @library /tools/lib * @modules * jdk.compiler/com.sun.tools.javac.api * jdk.compiler/com.sun.tools.javac.main * @build toolbox.ToolBox toolbox.JavacTask * @run main PreviewTest */ import java.lang.classfile.ClassModel; import java.lang.classfile.ClassFile; import java.io.InputStream; import java.nio.file.Files; import toolbox.JavacTask; import toolbox.Task; import toolbox.TestRunner; import toolbox.ToolBox; import java.nio.file.Path; import java.nio.file.Paths; import java.util.List; public class PreviewTest extends TestRunner { protected ToolBox tb; PreviewTest() { super(System.err); tb = new ToolBox(); } public static void main(String... args) throws Exception { PreviewTest t = new PreviewTest(); t.runTests(); } protected void runTests() throws Exception { runTests(m -> new Object[] { Paths.get(m.getName()) }); } @Test public void previewAPI(Path base) throws Exception { Path apiSrc = base.resolve("api-src"); tb.writeJavaFiles(apiSrc, """ package preview.api; public class OuterClass { @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.TEST) public void test() {} } """, """ package preview.api; public interface OuterIntf { @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.TEST) public void test(); } """, """ package preview.api; public interface OuterIntfDef { @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.TEST) public default void test() {}; } """); Path apiClasses = base.resolve("api-classes"); new JavacTask(tb, Task.Mode.CMDLINE) .outdir(apiClasses) .options("-XDrawDiagnostics", "--patch-module", "java.base=" + apiSrc.toString(), "-Werror") .files(tb.findJavaFiles(apiSrc)) .run() .writeAll() .getOutputLines(Task.OutputKind.DIRECT); Path testSrc = base.resolve("test-src"); tb.writeJavaFiles(testSrc, """ package test; import preview.api.OuterClass; public class UseClass1 extends OuterClass { } """, """ package test; public class UseSubClass11 extends UseClass1 { } """, """ package test; public class UseSubClass12P extends UseClass1 { public void test() {} } """, """ package test; import preview.api.OuterClass; public class UseClass2P extends OuterClass { public void test() {} } """, """ package test; public class UseSubClass21 extends UseClass2P { } """, """ package test; public class UseSubClass22 extends UseClass2P { public void test() {} } """, """ package test; import preview.api.OuterIntf; public class UseIntf2P implements OuterIntf { public void test() {} } """, """ package test; public class UseSubIntf21 extends UseIntf2P { } """, """ package test; public class UseSubIntf22 extends UseIntf2P { public void test() {} } """, """ package test; import preview.api.OuterIntfDef; public class UseIntfDef1 implements OuterIntfDef { } """, """ package test; public class UseSubIntfDef11 extends UseIntfDef1 { } """, """ package test; public class UseSubIntfDef12P extends UseIntfDef1 { public void test() {} } """, """ package test; import preview.api.OuterIntfDef; public class UseIntfDef2P implements OuterIntfDef { public void test() {} } """, """ package test; public class UseSubIntfDef21 extends UseIntfDef2P { } """, """ package test; public class UseSubIntfDef22 extends UseIntfDef2P { public void test() {} } """, """ package test; import preview.api.OuterIntf; public interface IUseIntf1 extends OuterIntf { } """, """ package test; import preview.api.OuterIntf; public interface IUseIntf2P extends OuterIntf { public default void test() {} } """, """ package test; import preview.api.OuterIntfDef; public interface IUseIntfDef1 extends OuterIntfDef { } """, """ package test; import preview.api.OuterIntfDef; public interface IUseIntfDef2P extends OuterIntfDef { public default void test() {} } """); Path testClasses = base.resolve("test-classes"); List log = new JavacTask(tb, Task.Mode.CMDLINE) .outdir(testClasses) .options("--patch-module", "java.base=" + apiClasses.toString(), "--add-exports", "java.base/preview.api=ALL-UNNAMED", "-XDrawDiagnostics") .files(tb.findJavaFiles(testSrc)) .run(Task.Expect.FAIL) .writeAll() .getOutputLines(Task.OutputKind.DIRECT); List expected = List.of("IUseIntf2P.java:4:25: compiler.err.is.preview: test()", "IUseIntfDef2P.java:4:25: compiler.err.is.preview: test()", "UseClass2P.java:4:17: compiler.err.is.preview: test()", "UseIntf2P.java:4:17: compiler.err.is.preview: test()", "UseIntfDef2P.java:4:17: compiler.err.is.preview: test()", "UseSubClass12P.java:3:17: compiler.err.is.preview: test()", "UseSubIntfDef12P.java:3:17: compiler.err.is.preview: test()", "7 errors"); if (!log.equals(expected)) throw new Exception("expected output not found" + log); Path[] sources = tb.findJavaFiles(testSrc); log = new JavacTask(tb, Task.Mode.CMDLINE) .outdir(testClasses) .options("--patch-module", "java.base=" + apiClasses.toString(), "--add-exports", "java.base/preview.api=ALL-UNNAMED", "--enable-preview", "-Xlint:preview", "-source", String.valueOf(Runtime.version().feature()), "-XDrawDiagnostics") .files(sources) .run(Task.Expect.SUCCESS) .writeAll() .getOutputLines(Task.OutputKind.DIRECT); expected = List.of("IUseIntf2P.java:4:25: compiler.warn.is.preview: test()", "IUseIntfDef2P.java:4:25: compiler.warn.is.preview: test()", "UseClass2P.java:4:17: compiler.warn.is.preview: test()", "UseIntf2P.java:4:17: compiler.warn.is.preview: test()", "UseIntfDef2P.java:4:17: compiler.warn.is.preview: test()", "UseSubClass12P.java:3:17: compiler.warn.is.preview: test()", "UseSubIntfDef12P.java:3:17: compiler.warn.is.preview: test()", "7 warnings"); if (!log.equals(expected)) throw new Exception("expected output not found" + log); int classfileCount = verifyPreviewClassfiles(testClasses); if (sources.length != classfileCount) { throw new IllegalStateException("Unexpected number of classfiles: " + classfileCount + ", number of source files: " + sources.length); } for (Path source : sources) { log = new JavacTask(tb, Task.Mode.CMDLINE) .classpath(testClasses) .outdir(testClasses) .options("--patch-module", "java.base=" + apiClasses.toString(), "--add-exports", "java.base/preview.api=ALL-UNNAMED", "--enable-preview", "-Xlint:preview", "-source", String.valueOf(Runtime.version().feature()), "-XDrawDiagnostics") .files(source) .run(Task.Expect.SUCCESS) .writeAll() .getOutputLines(Task.OutputKind.DIRECT); boolean preview = source.getFileName().toString().contains("P."); boolean hasWarning = false; for (String line : log) { hasWarning |= line.contains(source.getFileName().toString()) && line.contains("compiler.warn.is.preview: test()"); } if (preview != hasWarning) throw new Exception("expected " + (preview ? "preview" : "not preview") + "but got " + (hasWarning ? "warning" : "no warning") + "in: " + log); classfileCount = verifyPreviewClassfiles(testClasses); if (sources.length != classfileCount) { throw new IllegalStateException("Unexpected number of classfiles: " + classfileCount + ", number of source files: " + sources.length); } } } @Test public void previewAPIAbstractReAbstract(Path base) throws Exception { Path apiSrc = base.resolve("api-src"); tb.writeJavaFiles(apiSrc, """ package preview.api; public class Concrete { @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.TEST) public void test() {} } """, """ package preview.api; public abstract class Abstract { @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.TEST) public abstract void test(); } """); Path apiClasses = base.resolve("api-classes"); new JavacTask(tb, Task.Mode.CMDLINE) .outdir(apiClasses) .options("-XDrawDiagnostics", "-doe", "--patch-module", "java.base=" + apiSrc.toString(), "-Werror") .files(tb.findJavaFiles(apiSrc)) .run() .writeAll() .getOutputLines(Task.OutputKind.DIRECT); Path testSrc = base.resolve("test-src"); tb.writeJavaFiles(testSrc, """ package test; import preview.api.Concrete; public abstract class ReabstractP extends Concrete { public abstract void test(); } """, """ package test; public abstract class ReabstractSubclass1 extends ReabstractP { public abstract void test(); } """, """ package test; public class ReabstractSubclass2 extends ReabstractP { public void test() {} } """, """ package test; import preview.api.Abstract; public abstract class AbstractP extends Abstract { public abstract void test(); } """, """ package test; public abstract class AbstractSubclass1 extends AbstractP { public abstract void test(); } """, """ package test; public class AbstractSubclass2 extends AbstractP { public void test() {} } """); Path testClasses = base.resolve("test-classes"); List log = new JavacTask(tb, Task.Mode.CMDLINE) .outdir(testClasses) .options("--patch-module", "java.base=" + apiClasses.toString(), "--add-exports", "java.base/preview.api=ALL-UNNAMED", "-XDrawDiagnostics") .files(tb.findJavaFiles(testSrc)) .run(Task.Expect.FAIL) .writeAll() .getOutputLines(Task.OutputKind.DIRECT); List expected = List.of("AbstractP.java:4:26: compiler.err.is.preview: test()", "ReabstractP.java:4:26: compiler.err.is.preview: test()", "2 errors"); if (!log.equals(expected)) throw new Exception("expected output not found" + log); Path[] sources = tb.findJavaFiles(testSrc); log = new JavacTask(tb, Task.Mode.CMDLINE) .outdir(testClasses) .options("--patch-module", "java.base=" + apiClasses.toString(), "--add-exports", "java.base/preview.api=ALL-UNNAMED", "--enable-preview", "-Xlint:preview", "-source", String.valueOf(Runtime.version().feature()), "-XDrawDiagnostics") .files(sources) .run(Task.Expect.SUCCESS) .writeAll() .getOutputLines(Task.OutputKind.DIRECT); expected = List.of("AbstractP.java:4:26: compiler.warn.is.preview: test()", "ReabstractP.java:4:26: compiler.warn.is.preview: test()", "2 warnings"); if (!log.equals(expected)) throw new Exception("expected output not found" + log); int classfileCount = verifyPreviewClassfiles(testClasses); if (sources.length != classfileCount) { throw new IllegalStateException("Unexpected number of classfiles: " + classfileCount + ", number of source files: " + sources.length); } for (Path source : sources) { log = new JavacTask(tb, Task.Mode.CMDLINE) .classpath(testClasses) .outdir(testClasses) .options("--patch-module", "java.base=" + apiClasses.toString(), "--add-exports", "java.base/preview.api=ALL-UNNAMED", "--enable-preview", "-Xlint:preview", "-source", String.valueOf(Runtime.version().feature()), "-XDrawDiagnostics") .files(source) .run(Task.Expect.SUCCESS) .writeAll() .getOutputLines(Task.OutputKind.DIRECT); boolean preview = source.getFileName().toString().contains("P."); boolean hasWarning = false; for (String line : log) { hasWarning |= line.contains(source.getFileName().toString()) && line.contains("compiler.warn.is.preview: test()"); } if (preview != hasWarning) throw new Exception("expected " + (preview ? "preview" : "not preview") + "but got " + (hasWarning ? "warning" : "no warning") + "in: " + log); classfileCount = verifyPreviewClassfiles(testClasses); if (sources.length != classfileCount) { throw new IllegalStateException("Unexpected number of classfiles: " + classfileCount + ", number of source files: " + sources.length); } } } @Test //JDK-8343540: public void nonPreviewImplementsPreview(Path base) throws Exception { Path apiSrc = base.resolve("api-src"); tb.writeJavaFiles(apiSrc, """ package preview.api; @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.TEST) public interface Preview { public static final int FIELD = 0; public default void test() {} } """, """ package preview.api; @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.TEST, reflective=true) public interface ReflectivePreview { public default void test() {} } """, """ package preview.api; public interface NonPreviewIntf extends Preview { } """, """ package preview.api; public class NonPreview implements Preview { } """, """ package preview.api; public class ReflectiveNonPreview implements ReflectivePreview { } """); Path apiClasses = base.resolve("api-classes"); new JavacTask(tb, Task.Mode.CMDLINE) .outdir(apiClasses) .options("--patch-module", "java.base=" + apiSrc.toString(), "-Werror") .files(tb.findJavaFiles(apiSrc)) .run() .writeAll() .getOutputLines(Task.OutputKind.DIRECT); Path testSrc = base.resolve("test-src"); tb.writeJavaFiles(testSrc, """ package test; import preview.api.NonPreview; import preview.api.NonPreviewIntf; import preview.api.Preview; import preview.api.ReflectiveNonPreview; public class Test { public void test(NonPreview np, Produce prod) { np.test(); acceptRunnable(np::test); accept(NonPreview::test); prod.produce().test(); acceptRunnable(prod.produce()::test); int i = np.FIELD; } public void test(T1 t1, T2 t2, T3 t3) { t1.test(); t2.test(); t3.test(); } public void test(ReflectiveNonPreview np) { np.test(); } public void test(Preview p) { p.test(); acceptRunnable(p::test); accept(Preview::test); } private static class ExtendsNonPreview extends NonPreview { public void test() {} //error/warning here: } private static class ImplementsPreview implements Preview { //no error/warning (already was on Preview after implements) public void test() {} } private static class ImplicitReceiver extends NonPreview { public void g() { test(); //implicit this - error/warning int i = FIELD; //implicit this - error/warning } } private void acceptRunnable(Runnable r) {} private void accept(Accept accept) {} interface Accept { public void accept(T t); } interface Produce { public T produce(); } } """); Path testClasses = base.resolve("test-classes"); List log = new JavacTask(tb, Task.Mode.CMDLINE) .outdir(testClasses) .options("--patch-module", "java.base=" + apiClasses.toString(), "--add-exports", "java.base/preview.api=ALL-UNNAMED", "-XDrawDiagnostics") .files(tb.findJavaFiles(testSrc)) .run(Task.Expect.FAIL) .writeAll() .getOutputLines(Task.OutputKind.DIRECT); List expected = List.of("Test.java:4:19: compiler.err.is.preview: preview.api.Preview", "Test.java:26:22: compiler.err.is.preview: preview.api.Preview", "Test.java:34:55: compiler.err.is.preview: preview.api.Preview", "Test.java:9:11: compiler.err.is.preview: test()", "Test.java:10:24: compiler.err.is.preview: test()", "Test.java:11:16: compiler.err.is.preview: test()", "Test.java:12:23: compiler.err.is.preview: test()", "Test.java:13:24: compiler.err.is.preview: test()", "Test.java:14:19: compiler.err.is.preview: FIELD", "Test.java:19:11: compiler.err.is.preview: test()", "Test.java:20:11: compiler.err.is.preview: test()", "Test.java:21:11: compiler.err.is.preview: test()", "Test.java:29:16: compiler.err.is.preview: preview.api.Preview", "Test.java:32:21: compiler.err.is.preview: test()", "Test.java:36:21: compiler.err.is.preview: test()", "Test.java:40:13: compiler.err.is.preview: test()", "Test.java:41:21: compiler.err.is.preview: FIELD", "Test.java:24:11: compiler.warn.is.preview.reflective: test()", "17 errors", "1 warning"); if (!log.equals(expected)) throw new Exception("expected output not found" + log); } @Test //JDK-8343540: public void nonPreviewImplementsPreview2(Path base) throws Exception { Path apiSrc = base.resolve("api-src"); tb.writeJavaFiles(apiSrc, """ package preview.api; @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.TEST) public interface Preview { public default void test() {} } """, """ package preview.api; public interface NonPreviewIntf extends Preview { public default void test() {} } """, """ package preview.api; public class NonPreview implements Preview { public void test() {} } """); Path apiClasses = base.resolve("api-classes"); new JavacTask(tb, Task.Mode.CMDLINE) .outdir(apiClasses) .options("--patch-module", "java.base=" + apiSrc.toString(), "-Werror") .files(tb.findJavaFiles(apiSrc)) .run() .writeAll() .getOutputLines(Task.OutputKind.DIRECT); Path testSrc = base.resolve("test-src"); tb.writeJavaFiles(testSrc, """ package test; import preview.api.NonPreview; import preview.api.NonPreviewIntf; public class Test { public void test(NonPreview np1, NonPreviewIntf np2) { np1.test(); np2.test(); } } """); Path testClasses = base.resolve("test-classes"); List log = new JavacTask(tb, Task.Mode.CMDLINE) .outdir(testClasses) .options("--patch-module", "java.base=" + apiClasses.toString(), "--add-exports", "java.base/preview.api=ALL-UNNAMED", "-XDrawDiagnostics") .files(tb.findJavaFiles(testSrc)) .run(Task.Expect.SUCCESS) .writeAll() .getOutputLines(Task.OutputKind.DIRECT); } @Test //JDK-8343540: public void nonPreviewImplementsPreview3(Path base) throws Exception { Path apiSrc = base.resolve("api-src"); tb.writeJavaFiles(apiSrc, """ package preview.api; @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.TEST) public class Preview { public int field; public static void test() {} } """, """ package preview.api; public class NonPreview extends Preview { } """); Path apiClasses = base.resolve("api-classes"); new JavacTask(tb, Task.Mode.CMDLINE) .outdir(apiClasses) .options("--patch-module", "java.base=" + apiSrc.toString(), "-Werror") .files(tb.findJavaFiles(apiSrc)) .run() .writeAll() .getOutputLines(Task.OutputKind.DIRECT); Path testSrc = base.resolve("test-src"); tb.writeJavaFiles(testSrc, """ package test; import preview.api.NonPreview; import preview.api.Preview; public class Test { public void test(NonPreview np, Preview p) { NonPreview.test(); Preview.test(); int i1 = np.field; int i2 = p.field; } } """); Path testClasses = base.resolve("test-classes"); List log = new JavacTask(tb, Task.Mode.CMDLINE) .outdir(testClasses) .options("--patch-module", "java.base=" + apiClasses.toString(), "--add-exports", "java.base/preview.api=ALL-UNNAMED", "-XDrawDiagnostics") .files(tb.findJavaFiles(testSrc)) .run(Task.Expect.FAIL) .writeAll() .getOutputLines(Task.OutputKind.DIRECT); List expected = List.of("Test.java:3:19: compiler.err.is.preview: preview.api.Preview", "Test.java:5:37: compiler.err.is.preview: preview.api.Preview", "Test.java:6:19: compiler.err.is.preview: test()", "Test.java:7:9: compiler.err.is.preview: preview.api.Preview", "Test.java:8:20: compiler.err.is.preview: field", "5 errors"); if (!log.equals(expected)) throw new Exception("expected output not found" + log); } @Test //JDK-8343540: public void nonPreviewImplementsPreview4(Path base) throws Exception { Path apiSrc = base.resolve("api-src"); tb.writeJavaFiles(apiSrc, """ package preview.api; @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.TEST) public class Preview { public int field; public static void test() {} } """, """ package preview.api; public class NonPreview extends Preview { public int field; public static void test() {} } """); Path apiClasses = base.resolve("api-classes"); new JavacTask(tb, Task.Mode.CMDLINE) .outdir(apiClasses) .options("--patch-module", "java.base=" + apiSrc.toString(), "-Werror") .files(tb.findJavaFiles(apiSrc)) .run() .writeAll() .getOutputLines(Task.OutputKind.DIRECT); Path testSrc = base.resolve("test-src"); tb.writeJavaFiles(testSrc, """ package test; import preview.api.NonPreview; import preview.api.Preview; public class Test { public void test(NonPreview np, Preview p) { NonPreview.test(); Preview.test(); int i1 = np.field; int i2 = p.field; } } """); Path testClasses = base.resolve("test-classes"); List log = new JavacTask(tb, Task.Mode.CMDLINE) .outdir(testClasses) .options("--patch-module", "java.base=" + apiClasses.toString(), "--add-exports", "java.base/preview.api=ALL-UNNAMED", "-XDrawDiagnostics") .files(tb.findJavaFiles(testSrc)) .run(Task.Expect.FAIL) .writeAll() .getOutputLines(Task.OutputKind.DIRECT); List expected = List.of("Test.java:3:19: compiler.err.is.preview: preview.api.Preview", "Test.java:5:37: compiler.err.is.preview: preview.api.Preview", "Test.java:7:9: compiler.err.is.preview: preview.api.Preview", "3 errors"); if (!log.equals(expected)) throw new Exception("expected output not found" + log); } @Test //JDK-8224228: public void testSuppressWarnings(Path base) throws Exception { Path apiSrc = base.resolve("api-src"); tb.writeJavaFiles(apiSrc, """ package preview.api; @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.TEST) public class Preview { public static int test() { return 0; } } """); Path apiClasses = base.resolve("api-classes"); new JavacTask(tb, Task.Mode.CMDLINE) .outdir(apiClasses) .options("--patch-module", "java.base=" + apiSrc.toString(), "-Werror") .files(tb.findJavaFiles(apiSrc)) .run() .writeAll() .getOutputLines(Task.OutputKind.DIRECT); Path testSrc = base.resolve("test-src"); tb.writeJavaFiles(testSrc, """ package test; import preview.api.Preview; public class Test { public static class Example1 { public void method() { Preview.test(); // SHOULD get a warning here } } @SuppressWarnings("preview") public static class Example2 { public void method() { Preview.test(); // SHOULD NOT get a warning here } } public static class Example3 { @SuppressWarnings("preview") public void method() { Preview.test(); // SHOULD NOT get a warning here } } public static class Example4 { { Preview.test(); // SHOULD get a warning here } } @SuppressWarnings("preview") public static class Example5 { { Preview.test(); // SHOULD NOT get a warning here } } public static class Example6 { @SuppressWarnings("preview") int x = Preview.test(); // SHOULD NOT get a warning here } } """); Path testClasses = base.resolve("test-classes"); List log = new JavacTask(tb, Task.Mode.CMDLINE) .outdir(testClasses) .options("--patch-module", "java.base=" + apiClasses.toString(), "--add-exports", "java.base/preview.api=ALL-UNNAMED", "--enable-preview", "-Xlint:preview", "-source", String.valueOf(Runtime.version().feature()), "-XDrawDiagnostics") .files(tb.findJavaFiles(testSrc)) .run(Task.Expect.SUCCESS) .writeAll() .getOutputLines(Task.OutputKind.DIRECT); List expected = List.of("Test.java:7:11: compiler.warn.is.preview: preview.api.Preview", "Test.java:27:11: compiler.warn.is.preview: preview.api.Preview", "2 warnings"); if (!log.equals(expected)) throw new Exception("expected output not found: " + log); } @Test //JDK-8343540: public void nonPreviewImplementsPreview5(Path base) throws Exception { Path apiSrc = base.resolve("api-src"); tb.writeJavaFiles(apiSrc, """ package preview.api; @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.TEST) public interface Preview { public static final int CONST1 = 0; public static final int CONST2 = 0; } """, """ package preview.api; public interface NonPreviewIntf extends Preview { public static final int CONST2 = 0; } """, """ package preview.api; public class NonPreview implements Preview { public static final int CONST2 = 0; } """); Path apiClasses = base.resolve("api-classes"); new JavacTask(tb, Task.Mode.CMDLINE) .outdir(apiClasses) .options("--patch-module", "java.base=" + apiSrc.toString(), "-Werror") .files(tb.findJavaFiles(apiSrc)) .run() .writeAll() .getOutputLines(Task.OutputKind.DIRECT); Path testSrc = base.resolve("test-src"); tb.writeJavaFiles(testSrc, """ package test; import preview.api.NonPreview; import preview.api.NonPreviewIntf; import preview.api.Preview; public class Test { public void test() { int i1 = NonPreview.CONST1; int i2 = NonPreviewIntf.CONST1; int i3 = Preview.CONST1; int i4 = NonPreview.CONST2; int i5 = NonPreviewIntf.CONST2; int i6 = Preview.CONST2; } } """); Path testClasses = base.resolve("test-classes"); List log = new JavacTask(tb, Task.Mode.CMDLINE) .outdir(testClasses) .options("--patch-module", "java.base=" + apiClasses.toString(), "--add-exports", "java.base/preview.api=ALL-UNNAMED", "-XDrawDiagnostics") .files(tb.findJavaFiles(testSrc)) .run(Task.Expect.FAIL) .writeAll() .getOutputLines(Task.OutputKind.DIRECT); List expected = List.of("Test.java:4:19: compiler.err.is.preview: preview.api.Preview", "Test.java:7:28: compiler.err.is.preview: CONST1", "Test.java:8:32: compiler.err.is.preview: CONST1", "Test.java:9:18: compiler.err.is.preview: preview.api.Preview", "Test.java:12:18: compiler.err.is.preview: preview.api.Preview", "5 errors"); if (!log.equals(expected)) throw new Exception("expected output not found" + log); } private int verifyPreviewClassfiles(Path directory) throws Exception { Path[] classfiles = tb.findFiles("class", directory); for (Path classfile : classfiles) { boolean preview = classfile.getFileName().toString().contains("P."); checkPreviewClassfile(classfile, preview); } return classfiles.length; } private void checkPreviewClassfile(Path p, boolean preview) throws Exception { try (InputStream in = Files.newInputStream(p)) { ClassModel cf = ClassFile.of().parse(in.readAllBytes()); if (preview && cf.minorVersion() != 65535) { throw new IllegalStateException("Expected preview class, but got: " + cf.minorVersion() + " for: " + p.toString()); } else if (!preview && cf.minorVersion() != 0) { throw new IllegalStateException("Expected minor version == 0 but got: " + cf.minorVersion() + " for: " + p.toString()); } } } }