Java – Junit SuiteClasses with a static list of classes

javajunit4

SuiteClasses will work just fine with a list of classes like {Test1.class,Test2.class}, but when I try to generate a static list of classes, it says incompatible types: required java.lang.Class<?> but found java.lang.Class<?>[]

What am I missing?

@RunWith(Suite.class)

@Suite.SuiteClasses(TestSuite.classes)
public class TestSuite {

    public static Class<?> [] classes;

    static {
       classes = new Class<?> [1];
       classes[0] = MyTest.class;
    }
}

Best Solution

That shouldn't really work. You are intended to put the array within the annotation as a constant. Even if you got past this problem, the compiler would reject it. What you need to do is this:

@RunWith(Suite.class)

@Suite.SuiteClasses({MyTest.class, MyOtherTest.class})
public static class TestSuite {
}

Note the squiggly brackets.

I'm sure what you are trying to get at is to be able to build the list of classes in the suite dynamically.

I submitted a request to them to allow that, but in the mean time the only way to do it is to subclass the Suite class like so:

public class DynamicSuite extends Suite {

    public DynamicSuite(Class<?> setupClass) throws InitializationError {
       super(setupClass, DynamicSuiteBuilder.suite());
    }
}


@RunWith(DynamicSuite.class)
public class DynamicSuiteBuilder {
   public static Class[] suite() {
         //Generate class array here.
   }
}

Related Solutions

Java – How to test a class that has private methods, fields or inner classes

Update:

Some 10 years later perhaps the best way to test a private method, or any inaccessible member, is via @Jailbreak from the Manifold framework.
@Jailbreak Foo foo = new Foo();
// Direct, *type-safe* access to *all* foo's members
foo.privateMethod(x, y, z);
foo.privateField = value;
This way your code remains type-safe and readable. No design compromises, no overexposing methods and fields for the sake of tests.

If you have somewhat of a legacy Java application, and you're not allowed to change the visibility of your methods, the best way to test private methods is to use reflection.

Internally we're using helpers to get/set private and private static variables as well as invoke private and private static methods. The following patterns will let you do pretty much anything related to the private methods and fields. Of course, you can't change private static final variables through reflection.

Method method = TargetClass.getDeclaredMethod(methodName, argClasses);
method.setAccessible(true);
return method.invoke(targetObject, argObjects);

And for fields:

Field field = TargetClass.getDeclaredField(fieldName);
field.setAccessible(true);
field.set(object, value);

Notes:
1. TargetClass.getDeclaredMethod(methodName, argClasses) lets you look into private methods. The same thing applies for getDeclaredField.
2. The setAccessible(true) is required to play around with privates.

Java inner class and static nested class

From the Java Tutorial:

Nested classes are divided into two categories: static and non-static. Nested classes that are declared static are simply called static nested classes. Non-static nested classes are called inner classes.

Static nested classes are accessed using the enclosing class name:

OuterClass.StaticNestedClass

For example, to create an object for the static nested class, use this syntax:

OuterClass.StaticNestedClass nestedObject = new OuterClass.StaticNestedClass();

Objects that are instances of an inner class exist within an instance of the outer class. Consider the following classes:

class OuterClass {
    ...
    class InnerClass {
        ...
    }
}

An instance of InnerClass can exist only within an instance of OuterClass and has direct access to the methods and fields of its enclosing instance.

To instantiate an inner class, you must first instantiate the outer class. Then, create the inner object within the outer object with this syntax:

OuterClass outerObject = new OuterClass()
OuterClass.InnerClass innerObject = outerObject.new InnerClass();

see: Java Tutorial - Nested Classes

For completeness note that there is also such a thing as an inner class without an enclosing instance:

class A {
  int t() { return 1; }
  static A a =  new A() { int t() { return 2; } };
}

Here, new A() { ... } is an inner class defined in a static context and does not have an enclosing instance.

Best Solution

Related Solutions

Java – How to test a class that has private methods, fields or inner classes

Java inner class and static nested class

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