Introduce @Template and @TemplateCollection annotations

refaster-support/src/main/java/tech/picnic/errorprone/annotations/Template.java

@@ -0,0 +1,20 @@
+package tech.picnic.errorprone.annotations;
+
+import java.lang.annotation.ElementType;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Links the test method to the Refaster template under test. This allows for more extensive
+ * automatic verification of the tests. For instance, verify that every template has a test and the
+ * provided Refaster template _does_ change the content of the test method when it is applied.
+ */
+@TypeQualifierDefault(ElementType.METHOD)
+public @interface Template {
+  /**
+   * The class of the Refaster template that should be applied to the method body of the test
+   * method.
+   *
+   * @return class of the Refaster template
+   */
+  Class<?> value();
+}

refaster-support/src/main/java/tech/picnic/errorprone/annotations/TemplateCollection.java

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+package tech.picnic.errorprone.annotations;
+
+import java.lang.annotation.ElementType;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Links the `*TemplatesTest{Input,Output} file to the collection of Refaster templates that are
+ * tested in the class annotated with this annotation. As a value it should reference a class that
+ * contains a collection of Refaster templates.
+ *
+ * <p>As a result of this annotation, we can perform additional validations. For instance, make sure
+ * that the order of the templates matches the order in which the Refaster templates are defined.
+ */
+@TypeQualifierDefault(ElementType.TYPE)
+public @interface TemplateCollection {
+  /**
+   * The class of the Refaster template that should be applied to the method body of the test
+   * method.
+   *
+   * @return class of the Refaster template
+   */
+  Class<?> value();
+}