Feature summary

Add assertions for classes in the java.lang.reflect package:

• Field
• Method
• Constructor

In this issue, we will add support for visiblity modifiers, static / final modifiers and annotations:

• MemberAssert: isPublic(), isProtected(), isPackagePrivate()
• AnnotatedElementAssert: hasAnnotation(Class), hasAnnotations(Class...)
• MethodAssert: isAbstract(), isStatic(), isNotStatic(), isFinal(), isNotFinal()
• FieldAssert: isStatic(), isNotStatic(), isFinal(), isNotFinal()

Example

Field field = Math.class.getDeclaredField("PI");
assertThat(field).isPublic();
assertThat(field).isStatic();
assertThat(field).isFinal();

Method method = Math.class.getDeclaredMethod("abs", long.class);
assertThat(method).isPublic();
assertThat(method).isStatic();
assertThat(method).isNotFinal();

Constructor<?> constructor = String.class.getDeclaredConstructor();
assertThat(constructor).isPublic();

Limitations / Future considerations

• Not all methods and properties of Field, Method and Constructor are covered in this issue. Further features can be added in later issues.
• Not all classes in the java.lang.reflect package are covered in this issue. Support for Parameter can be added in later issues.
• You should obtain a reference to the Field, Method and Constructor. In later iterations, we could consider adding a method to ClassAssert to extract members, so one can navigate fluently to the Field, Method and Constructor. This is left out of scope as it requires further thought about visibility, exceptions and method overloading. For example:

class ClassAssert {
    FieldAssert extractingField(String name);
    MethodAssert extractingMethod(String name);
    ConstructorAssert extractingConstructor(String name);
}

• The Assertions and BDDAssertions entry points are very large. We could introduce an interface with static methods for the assertion methods related to the java.lang.reflect package and implement this interface in the Assertions entry point.

See also:

• add constructor assertions for ClassAssert #1693
• Add ConstructorAssert instead of using ClassAssert #1869
• Add ConstructorAssert instead of using ClassAssert #1871