The implementation of a Rule might look like this:
import org.junit.rules.TestRule;
import org.junit.runner.Description;
import org.junit.runners.model.Statement;
public class LoggingRule implements TestRule {
public class LoggingStatement extends Statement {
private final Statement statement;
public LoggingStatement(Statement aStatement, String aName) {
statement = aStatement;
}
@Override
public void evaluate() throws Throwable {
System.out.println("before: " + name);
statement.evaluate();
System.out.println("after: " + name);
}
}
private final String name;
public LoggingRule(String aName) {
name = aName;
}
@Override
public Statement apply(Statement statement, Description description) {
System.out.println("apply: " + name);
return new LoggingStatement(statement, name);
}
}
A test class using this Rule might look like this:
import org.junit.ClassRule;
import org.junit.Rule;
import org.junit.Test;
public class RuleTest {
@ClassRule
public static LoggingRule classRule = new LoggingRule("classrule");
@Rule
public static LoggingRule rule = new LoggingRule("rule");
@Test
public void testSomething() {
System.out.println("In TestSomething");
assertTrue(true);
}
@Test
public void testSomethingElse() {
System.out.println("In TestSomethingElse");
assertTrue(true);
}
}
Output:
apply: classrule
before: classrule
apply: rule
before: rule
In TestSomething
after: rule
apply: rule
before: rule
In TestSomethingElse
after: rule
after: classrule
Related Article:
Reference: Rules in JUnit 4.9 (beta 3) from our JCG partner Jens Schauder at the Schauderhaft blog
