How do I test a Generator in GWT?

Question

In GWT the code for a Generator is located in the rebind package. This package is not included in the module xml file, since it might contain non client code.

Here is what I did. My module file is /test/gwttest.gwt.xml. It contains the following:

<generate-with class="test.rebind.FunctionGenerator">
    <when-type-assignable class="test.client.Function" />
</generate-with>

<source path='client'/>

Here is /test/client/Function:

public interface Function {
    public Object execute();
}

My Generator is /test/rebind/FunctionGenerator:

public class FunctionGenerator extends Generator {
    private static final String IMPL_TYPE_NAME = Function.class.getSimpleName()
            + "Impl";
    private static final String IMPL_PACKAGE_NAME = Function.class.getPackage()
            .getName();

    @Override
    public String generate(TreeLogger logger, GeneratorContext context,
            String requestedClass) throws UnableToCompleteException {
        TypeOracle typeOracle = context.getTypeOracle();
        JClassType functionType = typeOracle.findType(requestedClass);
        assert Function.class.equals(functionType.getClass());

        ClassSourceFileComposerFactory composerFactory = new ClassSourceFileComposerFactory(
                IMPL_PACKAGE_NAME, IMPL_TYPE_NAME);

        composerFactory.addImport(Function.class.getCanonicalName());
        composerFactory.addImplementedInterface(Function.class.getName());

        PrintWriter printWriter = context.tryCreate(logger, IMPL_PACKAGE_NAME,
                IMPL_TYPE_NAME);
        SourceWriter sourceWriter = composerFactory.createSourceWriter(context,
                printWriter);

        sourceWriter.print("public Object execute() {");
        sourceWriter.print("    return 1;");
        sourceWriter.print("}");

        sourceWriter.commit(logger);
        return IMPL_PACKAGE_NAME + "." + IMPL_TYPE_NAME;
    }
}

My GeneratorTest is /test/rebind/FunctionGeneratorTest:

public class FunctionGeneratorTest extends GWTTestCase {

    @Override
    public String getModuleName() {
        return "com.acme.gwt.Generator";
    }

    public void testGenerator() throws Exception {
        Function function = GWT.create(Function.class);
        assertNotNull(function);
        assertEquals(1, function.execute());
    }
}

The test always fails because with this error:

com.google.gwt.junit.JUnitFatalLaunchException: The test class 'test.rebind.FunctionGeneratorTest' was not found in module 'test.Gwttest'; no compilation unit for that type was seen
    at com.google.gwt.junit.JUnitShell.checkTestClassInCurrentModule(JUnitShell.java:766)
    at com.google.gwt.junit.JUnitShell.runTestImpl(JUnitShell.java:1349)
    at com.google.gwt.junit.JUnitShell.runTestImpl(JUnitShell.java:1311)
    at com.google.gwt.junit.JUnitShell.runTest(JUnitShell.java:705)
    at com.google.gwt.junit.client.GWTTestCase.runTest(GWTTestCase.java:421)
    at junit.framework.TestCase.runBare(TestCase.java:141)
    at junit.framework.TestResult$1.protect(TestResult.java:122)
    at junit.framework.TestResult.runProtected(TestResult.java:142)
    at junit.framework.TestResult.run(TestResult.java:125)
    at junit.framework.TestCase.run(TestCase.java:129)
    at com.google.gwt.junit.client.GWTTestCase.run(GWTTestCase.java:247)
    at junit.framework.TestSuite.runTest(TestSuite.java:255)
    at junit.framework.TestSuite.run(TestSuite.java:250)
    at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:84)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

I cannot include the rebind folder as source in my module file since it is no client code.

What do I have to do?

When I move the test from /test/rebind to /test/client it works with Eclipse Run as > GWT Unit Test.

When I try Eclipse Run as > GWT Unit Test (production mode) the test fails.

Here is the trace:

com.google.gwt.core.ext.UnableToCompleteException: (see previous log entries)
    at com.google.gwt.junit.JUnitShell.compileForWebMode(JUnitShell.java:1125)
    at com.google.gwt.junit.JUnitShell.maybeCompileForWebMode(JUnitShell.java:1174)
    at com.google.gwt.junit.CompileStrategy.maybeCompileModuleImpl2(CompileStrategy.java:180)
    at com.google.gwt.junit.CompileStrategy.maybeCompileModuleImpl(CompileStrategy.java:112)
    at com.google.gwt.junit.SimpleCompileStrategy.maybeCompileModule(SimpleCompileStrategy.java:36)
    at com.google.gwt.junit.JUnitShell.runTestImpl(JUnitShell.java:1342)
    at com.google.gwt.junit.JUnitShell.runTestImpl(JUnitShell.java:1311)
    at com.google.gwt.junit.JUnitShell.runTest(JUnitShell.java:705)
    at com.google.gwt.junit.client.GWTTestCase.runTest(GWTTestCase.java:421)
    at junit.framework.TestCase.runBare(TestCase.java:141)
    at junit.framework.TestResult$1.protect(TestResult.java:122)
    at junit.framework.TestResult.runProtected(TestResult.java:142)
    at junit.framework.TestResult.run(TestResult.java:125)
    at junit.framework.TestCase.run(TestCase.java:129)
    at com.google.gwt.junit.client.GWTTestCase.run(GWTTestCase.java:247)
    at junit.framework.TestSuite.runTest(TestSuite.java:255)
    at junit.framework.TestSuite.run(TestSuite.java:250)
    at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:84)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

Why does the test fails in production mode and passes in dev mode?

Answer 1

See this link: https://groups.google.com/forum/#!topic/google-web-toolkit/OyH839KEH-w

This will help to make the production code working:

PrintWriter printWriter = context.tryCreate(logger, IMPL_PACKAGE_NAME, IMPL_TYPE_NAME);
if (printWriter != null) {
....
} 
return IMPL_PACKAGE_NAME + "." + IMPL_TYPE_NAME;