/**
*
*/
package org.junit.rules;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.junit.runner.Description;
import org.junit.runners.model.Statement;
/**
* The RuleChain rule allows ordering of TestRules. You create a
* {@code RuleChain} with {@link #outerRule(TestRule)} and subsequent calls of
* {@link #around(TestRule)}:
*
* <pre>
* public static class UseRuleChain {
* @Rule
* public TestRule chain= RuleChain
* .outerRule(new LoggingRule("outer rule")
* .around(new LoggingRule("middle rule")
* .around(new LoggingRule("inner rule");
*
* @Test
* public void example() {
* assertTrue(true);
* }
* }
* </pre>
*
* writes the log
*
* <pre>
* starting outer rule
* starting middle rule
* starting inner rule
* finished inner rule
* finished middle rule
* finished outer rule
* </pre>
*/
public class RuleChain implements TestRule {
private static final RuleChain EMPTY_CHAIN= new RuleChain(
Collections.<TestRule> emptyList());
private List<TestRule> rulesStartingWithInnerMost;
/**
* Returns a {@code RuleChain} without a {@link TestRule}. This method may
* be the starting point of a {@code RuleChain}.
*
* @return a {@code RuleChain} without a {@link TestRule}.
*/
public static RuleChain emptyRuleChain() {
return EMPTY_CHAIN;
}
/**
* Returns a {@code RuleChain} with a single {@link TestRule}. This method
* is the usual starting point of a {@code RuleChain}.
*
* @param outerRule
* the outer rule of the {@code RuleChain}.
* @return a {@code RuleChain} with a single {@link TestRule}.
*/
public static RuleChain outerRule(TestRule outerRule) {
return emptyRuleChain().around(outerRule);
}
private RuleChain(List<TestRule> rules) {
this.rulesStartingWithInnerMost= rules;
}
/**
* Create a new {@code RuleChain}, which encloses the {@code nextRule} with
* the rules of the current {@code RuleChain}.
*
* @param enclosedRule
* the rule to enclose.
* @return a new {@code RuleChain}.
*/
public RuleChain around(TestRule enclosedRule) {
List<TestRule> rulesOfNewChain= new ArrayList<TestRule>();
rulesOfNewChain.add(enclosedRule);
rulesOfNewChain.addAll(rulesStartingWithInnerMost);
return new RuleChain(rulesOfNewChain);
}
/**
* {@inheritDoc}
*/
public Statement apply(Statement base, Description description) {
for (TestRule each : rulesStartingWithInnerMost)
base= each.apply(base, description);
return base;
}
}
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