1 files changed, 92 insertions, 0 deletions
diff --git a/junit4/src/main/java/org/junit/internal/runners/rules/RuleFieldValidator.java b/junit4/src/main/java/org/junit/internal/runners/rules/RuleFieldValidator.java
new file mode 100644
index 0000000..e7df8bf
--- /dev/null
+++ b/junit4/src/main/java/org/junit/internal/runners/rules/RuleFieldValidator.java
@@ -0,0 +1,92 @@
+package org.junit.internal.runners.rules;
+
+import java.lang.annotation.Annotation;
+import java.util.List;
+
+import org.junit.ClassRule;
+import org.junit.Rule;
+import org.junit.rules.TestRule;
+import org.junit.runners.model.FrameworkField;
+import org.junit.runners.model.TestClass;
+
+/**
+ * A RuleFieldValidator validates the rule fields of a
+ * {@link org.junit.runners.model.TestClass}. All reasons for rejecting the
+ * {@code TestClass} are written to a list of errors.
+ * 
+ * There are two slightly different validators. The {@link #CLASS_RULE_VALIDATOR}
+ * validates fields with a {@link ClassRule} annotation and the
+ * {@link #RULE_VALIDATOR} validates fields with a {@link Rule} annotation.
+ */
+public enum RuleFieldValidator {
+	/**
+	 * Validates fields with a {@link ClassRule} annotation.
+	 */
+	CLASS_RULE_VALIDATOR(ClassRule.class, true),
+	/**
+	 * Validates fields with a {@link Rule} annotation.
+	 */
+	RULE_VALIDATOR(Rule.class, false);
+
+	private final Class<? extends Annotation> fAnnotation;
+
+	private final boolean fOnlyStaticFields;
+
+	private RuleFieldValidator(Class<? extends Annotation> annotation,
+			boolean onlyStaticFields) {
+		this.fAnnotation= annotation;
+		this.fOnlyStaticFields= onlyStaticFields;
+	}
+
+	/**
+	 * Validate the {@link org.junit.runners.model.TestClass} and adds reasons
+	 * for rejecting the class to a list of errors.
+	 * @param target the {@code TestClass} to validate.
+	 * @param errors the list of errors.
+	 */
+	public void validate(TestClass target, List<Throwable> errors) {
+		List<FrameworkField> fields= target.getAnnotatedFields(fAnnotation);
+		for (FrameworkField each : fields)
+			validateField(each, errors);
+	}
+
+	private void validateField(FrameworkField field, List<Throwable> errors) {
+		optionallyValidateStatic(field, errors);
+		validatePublic(field, errors);
+		validateTestRuleOrMethodRule(field, errors);
+	}
+
+	private void optionallyValidateStatic(FrameworkField field,
+			List<Throwable> errors) {
+		if (fOnlyStaticFields && !field.isStatic())
+			addError(errors, field, "must be static.");
+	}
+
+	private void validatePublic(FrameworkField field, List<Throwable> errors) {
+		if (!field.isPublic())
+			addError(errors, field, "must be public.");
+	}
+
+	private void validateTestRuleOrMethodRule(FrameworkField field,
+			List<Throwable> errors) {
+		if (!isMethodRule(field) && !isTestRule(field))
+			addError(errors, field, "must implement MethodRule or TestRule.");
+	}
+
+	private boolean isTestRule(FrameworkField target) {
+		return TestRule.class.isAssignableFrom(target.getType());
+	}
+
+	@SuppressWarnings("deprecation")
+	private boolean isMethodRule(FrameworkField target) {
+		return org.junit.rules.MethodRule.class.isAssignableFrom(target
+				.getType());
+	}
+
+	private void addError(List<Throwable> errors, FrameworkField field,
+			String suffix) {
+		String message= "The @" + fAnnotation.getSimpleName() + " '"
+				+ field.getName() + "' " + suffix;
+		errors.add(new Exception(message));
+	}
+}