As shown in a the post Nifty JUnit : Working with temporary files, it is possible to use @Rule in a JUnit test, which is a Method level Rule. In this example I would like to show the variation of the @ClassRule for a Class level Rule.
Method Rule
The @Rule is fired before each test method (just like @Before) and after each test method (just like @After) of the test class, as shown in the example below.
JUnitRuleTest
package com.jdriven;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TemporaryFolder;
import java.io.File;
import java.io.IOException;
public class JUnitRuleTest {
//The Folder will be created before each test method and (recursively) deleted after each test method.
@Rule
public TemporaryFolder temporaryFolder = new TemporaryFolder();
@Test
public void testJUnitRule() throws IOException {
File tempFile = temporaryFolder.newFile("tempFile.txt");
//Your test should go here.
}
}Class Rule
Besides the regular @Rule we have the possibility to create a @ClassRule. In the example of the TemporaryFolder it will result in a folder which is created before all test methods (just like @BeforeClass) and destroyed after all test methods (just like @AfterClass). In the example below you can create a temporary file and use the exact same file in all the test methods. The temporary file will be deleted when all the test methods are finished.
JUnitClassRuleTest
package com.jdriven;
import org.junit.BeforeClass;
import org.junit.ClassRule;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TemporaryFolder;
import java.io.File;
import java.io.IOException;
public class JUnitClassRuleTest {
//The Folder will be (recursively) deleted after all test.
@ClassRule
public static TemporaryFolder temporaryFolder = new TemporaryFolder();
public static File tempFile;
@BeforeClass
public static void createTempFile() throws IOException {
tempFile = temporaryFolder.newFile("tempFile.txt"); //The tempFile will be deleted when the temporaryFolder is deleted.
}
@Test
public void testJUnitClassRule_One() {
//Your test should go here, which uses tempFile
}
@Test
public void testJUnitClassRule_Two() {
//Your test should go here and uses the same tempFile
}
}| Reference: | Nifty JUnit : Using Rule on Method and Class level from our JCG partner Willem Cheizoo at the JDriven blog. |
