test-accessors

An annotation processor that generates code for your tests to be able to access and modify private/final fields so you don't have to use anti-patterns such as @VisibleForTesting!

Usage

Add the dependencies to your project:

repositories {
  google()
  mavenCentral()
}
dependencies {
    // 1. Add the annotation
    implementation "com.github.stoyicker.test-accessors:annotations:<version>"
    // 2. Add the processor
    annotationProcessor "com.github.stoyicker.test-accessors:processor-java:<version>"
}

Annotate your field:

public final class MyClass {
    @RequiresAccessor(requires = {RequiresAccessor.AccessorType.TYPE_GETTER, RequiresAccessor.AccessorType.TYPE_SETTER})
    private final String myField = "hola hola";
}

Once annotation processing runs, there will be a class in the generated directory of your source set with two methods like this:

public final class MyClassTestAccessors {
    public static String getMyField(final MyClass receiver);
    
    public static void setMyField(final MyClass receiver, final String newValue);
}

As you can see, things work perfectly fine even with final fields. Moreover, it also works with static fields!

class MyClass {
    @RequiresAccessor(requires = {RequiresAccessor.AccessorType.TYPE_GETTER, RequiresAccessor.AccessorType.TYPE_SETTER})
    private static final String myStaticField = "static hola hola";
}

will generate an implementation under the following API in the current source set:

public final class MyClassTestAccessors {
    public static String getMyStaticField();
    
    public static void setMyStaticField(final String newValue);
}

The different sample projects within the repo showcase how to use all the possibilities that the processor offers, so check them out if you're feeling lost!

Options

Annotation level

The annotation has some parameters you can use to alter its behavior:

• name -> Allows you to change the name of the methods that will be generated for the field you are annotating. If unspecified, the name of the generated accessor will be get/set plus the field name with the first character uppercase.
• requires -> Allows you to specify which type of accessor you want (use AccessorType.TYPE_GETTER for getter and/ or AccessorType.TYPE_SETTER for setter) for your annotated field. If unspecified, only a setter will be generated.
• androidXRestrictTo -> Allows you to declare an instance of androidx.annotation.RestrictTo that will be added to the method(s) generated due to this annotation. If unspecified or the scope array that describes the restrictions is empty, no androidX RestrictTo annotation will be added to methods generated due to this annotation occurrence (unless overriden by testaccessors.defaultAndroidXRestrictTo, see below).
• supportRestrictTo -> Allows you to declare an instance of android.support.annotation.RestrictTo that will be added to the method(s) generated due to this annotation. If unspecified or the scope array that describes the restrictions is empty, no support RestrictTo annotation will be added to methods generated due to this annotation occurrence (unless overriden by testaccessors.defaultSupportRestrictTo, see below).

Processor level

• testaccessors.requiredClasses -> Allows you to specify a list of comma-separated class names that will be 'pinged' every time a generated method runs, triggering an exception if none of them are found. This allows you to ensure that generated methods are not used where they should not (such as outside of tests) by passing in classes that are specific to test artifacts. If unspecified, it becomes a list of junit.runner.BaseTestRunner (for JUnit 4), org.junit.jupiter.api.Test (for JUnit 5) and org.testng.TestNG (for TestNG).
• testaccessors.defaultAndroidXRestrictTo -> Allows you to specify a default androidx.annotation.RestrictTo scope that will cause all occurrences of RequiresAccessors to change their default value for androidXRestrictTo to an instance of RestrictTo with that scope. Must be a comma-separated String formed by one or more of "LIBRARY", "LIBRARY_GROUP", "GROUP_ID", "TESTS" and "SUBCLASSES".
• testaccessors.defaultSupportRestrictTo -> Allows you to specify a default android.support.annotation.RestrictTo scope that will cause all occurrences of RequiresAccessors to change their default value for supportRestrictTo to an instance of RestrictTo with that scope. Must be a comma-separated String formed by one or more of "LIBRARY", "LIBRARY_GROUP", "GROUP_ID", "TESTS" and "SUBCLASSES".

How do I pass arguments to the annotation processor?

Non-Android Java:

compileJava {
    options.compilerArgs.addAll(['-Atestaccessors.requiredClasses=yourFirstClass,yourSecondClass'])
}

Android:

android {
  defaultConfig {
    javaCompileOptions {
      annotationProcessorOptions {
        arguments = ['testaccessors.requiredClasses': 'yourFirstClass,yourSecondClass']
      }
    }
  }
}

Drawbacks?

Classpath bloat: If you don't use the generated methods outside of tests, a simple shrinking ProGuard configuration such as this one will make sure that your classpath does not get affected at all.