instanceof_onemethod

public abstract class Change {

    private final String _id;

    protected Change(String id) {
        _id = id;
    }

    public abstract void verifyChangeOn(Code code);

    @Override
    public String toString() {
        return this.getClass().getSimpleName() + "(" + _id + ")";
    }

    public abstract CodeDelta process(Code code);
}

public class ChangeProcessingHandler {

    public CodeDelta triggerProcessingChangeOf(Code code, Change change) {
        verifyChangeOf(code, change);
        return change.process(code);
    }

    private void verifyChangeOf(Code code, Change change) {
        // TODO: Add verification logic here.
        change.verifyChangeOn(code);
    }

    // some more code
}

import junit.framework.TestCase;

public class ChangeProcessingHandlerTest extends TestCase {

    public void testRefactoring() {
        ChangeProcessingHandler handler = new ChangeProcessingHandler();
        Refactoring refactoring = new Refactoring("my test Refactoring instance for " + this.getName());
        Code code = new MockCode("my Code for " + this.getName());

        CodeDelta delta = handler.triggerProcessingChangeOf(code, refactoring);

        assertEquals("CodeDelta(MockCode(my Code for testRefactoring), Refactoring(my test Refactoring instance for testRefactoring))", delta.toString());
    }

    public void testRefactoringError() {
        final MockVerifyChangeException mockVerifyChangeException = new MockVerifyChangeException();

        Refactoring refactoring = new Refactoring("my test Refactoring instance for " + this.getName()) {
            @Override
            public void verifyChangeOn(Code code) {
                throw mockVerifyChangeException;
            }
        };
        ChangeProcessingHandler handler = new ChangeProcessingHandler();
        Code code = new MockCode("my Code for " + this.getName());

        try {
            handler.triggerProcessingChangeOf(code, refactoring);
            fail("Expecting MockVerifyChangeException.");
        } catch (MockVerifyChangeException verifyChangeException) {
            assertSame(mockVerifyChangeException, verifyChangeException);
        }
    }

    public void testGrowth() {
        ChangeProcessingHandler handler = new ChangeProcessingHandler();
        Growth growth = new Growth("my test Growth instance for " + this.getName());
        Code code = new MockCode("my Code for " + this.getName());

        CodeDelta delta = handler.triggerProcessingChangeOf(code, growth);

        assertEquals("CodeDelta(MockCode(my Code for testGrowth), Growth(my test Growth instance for testGrowth))", delta.toString());
    }

    public void testGrowthError() {
        final MockVerifyChangeException mockVerifyChangeException = new MockVerifyChangeException();

        Growth growth = new Growth("my test Growth instance for " + this.getName()) {
            @Override
            public void verifyChangeOn(Code code) {
                throw mockVerifyChangeException;
            }
        };
        ChangeProcessingHandler handler = new ChangeProcessingHandler();
        Code code = new MockCode("my Code for " + this.getName());

        try {
            handler.triggerProcessingChangeOf(code, growth);
            fail("Expecting MockVerifyChangeException.");
        } catch (MockVerifyChangeException verifyChangeException) {
            assertSame(mockVerifyChangeException, verifyChangeException);
        }
    }

    public void testImprovement() {
        ChangeProcessingHandler handler = new ChangeProcessingHandler();
        Improvement improvement = new Improvement("my test Improvement instance for " + this.getName());
        Code code = new MockCode("my Code for " + this.getName());

        CodeDelta delta = handler.triggerProcessingChangeOf(code, improvement);

        assertEquals("CodeDelta(MockCode(my Code for testImprovement), Improvement(my test Improvement instance for testImprovement))", delta.toString());
    }

    public void testImprovementError() {
        final MockVerifyChangeException mockVerifyChangeException = new MockVerifyChangeException();

        Improvement improvement = new Improvement("my test Improvement instance for " + this.getName()) {
            @Override
            public void verifyChangeOn(Code code) {
                throw mockVerifyChangeException;
            }
        };
        ChangeProcessingHandler handler = new ChangeProcessingHandler();
        Code code = new MockCode("my Code for " + this.getName());

        try {
            handler.triggerProcessingChangeOf(code, improvement);
            fail("Expecting MockVerifyChangeException.");
        } catch (MockVerifyChangeException verifyChangeException) {
            assertSame(mockVerifyChangeException, verifyChangeException);
        }
    }

}

public interface Code {
}

public class CodeDelta {

    private final String _id;

    public CodeDelta(String id) {
        _id = id;
    }

    @Override
    public String toString() {
        return "CodeDelta(" + _id + ")";
    }
}

public class Growth extends Change {

    public Growth(String id) {
        super(id);
    }

    @Override
    public void verifyChangeOn(Code code) {
        // TODO: Add verification logic here.
    }

    @Override
    public CodeDelta process(Code code) {
        return new CodeDelta(code.toString() + ", " + this.toString());
    }

    // some code
}

public class Improvement extends Change {

    public Improvement(String id) {
        super(id);
    }

    @Override
    public void verifyChangeOn(Code code) {
        // TODO: Add verification logic here.
    }

    @Override
    public CodeDelta process(Code code) {
        return new CodeDelta(code.toString() + ", " + this.toString());
    }

    // some code
}

public class MockCode implements Code {

    final String _id;

    public MockCode(String id) {
        _id = id;
    }

    @Override
    public String toString() {
        return "MockCode(" + _id + ")";
    }

}

public class MockVerifyChangeException extends RuntimeException {
}

public class Refactoring extends Change {

    public Refactoring(String id) {
        super(id);
    }

    @Override
    public void verifyChangeOn(Code code) {
        // TODO: Add verification logic here.
    }

    @Override
    public CodeDelta process(Code code) {
        return new CodeDelta(code.toString() + ", " + this.toString());
    }

    // some code
}