name.didier.david.test4j.junit.TestResourceRule Maven / Gradle / Ivy

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package name.didier.david.test4j.junit;

import java.io.File;
import java.lang.reflect.Method;
import java.net.URL;

import org.junit.rules.MethodRule;
import org.junit.runners.model.FrameworkMethod;
import org.junit.runners.model.Statement;

import name.didier.david.test4j.unit.TestResourceHandler;

/**
 * Provide resource injection explicitly or through {@link name.didier.david.test4j.unit.TestResource} annotations.
 *
 * 
 * The pattern is a custom string which may use the following placeholders:
 * 
 *
 * 
 * {c} is the name of the current test class, given by {@link Class#getSimpleName()}, e.g.
 * MyTestCase or MyTestCase-MyInnerClass
 * {f} is the name of the annotated field, given by {@link java.lang.reflect.Field#getName()}
 * {m} is the name of the current test method, given by {@link java.lang.reflect.Method#getName()}
 * {p} is the package name of the current test class as a path, given by {@link Package#getName()},
 * e.g. name/didier/david/test4j/junit
 * 
 *
 * 
 * Usage:
 * 
 *
 *    package name.didier.david.test4j.junit;

   public class TestResourceRuleTest {

     @Rule
     public TestResourceRule testResource = new TestResourceRule();

     // resolves to name/didier/david/test4j/junit/TestResourceRuleTest-data/<method_name>
     // with <method_name> the name ot the current running test method, e.g. "test"
     @TestResource("/{p}/{c}-data/{m}")
     private File fileField;

     // resolves to the content of name/didier/david/test4j/testng/TestNgResourceListenerTest-data/<method_name>
     // with <method_name> the name ot the current running test method, e.g. "test"
     @TestResource("/{p}/{c}-data/{m}")
     private String stringField;

     @Test
     public void test() {
       // resolves to name/didier/david/test4j/junit/TestResourceRuleTest-data/test
       File file = testResource.asFile("/{p}/{c}-data/{m}");
       // resolves to the content of name/didier/david/test4j/junit/TestResourceRuleTest-data/test
       String fileContent = testResource.asContent("/{p}/{c}-data/{m}");
       ...
     }
   }
 * 
 *
 * @author ddidier
 */
public class TestResourceRule
        implements MethodRule {

    /** Handle {@link name.didier.david.test4j.unit.TestResource}s. */
    private final TestResourceHandler handler;
    /** The current instance under test. */
    private Object testInstance;
    /** The current method under test. */
    private Method testMethod;

    /** Default constructor. */
    public TestResourceRule() {
        handler = new TestResourceHandler();
    }

    @Override
    public Statement apply(Statement base, FrameworkMethod method, Object target) {
        return new Statement() {

            @Override
            public void evaluate()
                    throws Throwable {
                before(base, method, target);
                try {
                    base.evaluate();
                } finally {
                    after(base, method, target);
                }
            }
        };
    }

    /**
     * Find the resource with the given pattern as a {@link File}, relative to the current test class and method.
     *
     * @param pattern the pattern to search for.
     * @return the file if found.
     * @throws name.didier.david.test4j.unit.TestResourceException if the file cannot be found.
     */
    public File asFile(String pattern) {
        return handler.findFile(pattern, testInstance, testMethod);
    }

    /**
     * Find the resource with the given pattern as a {@link URL}, relative to the current test class and method.
     *
     * @param pattern the pattern to search for.
     * @return the URL if found.
     * @throws name.didier.david.test4j.unit.TestResourceException if the URL cannot be found.
     */
    public URL asUrl(String pattern) {
        return handler.findUrl(pattern, testInstance, testMethod);
    }

    /**
     * Load the content of the resource with the given pattern, relative to the current test class and method.
     *
     * @param pattern the pattern to search for.
     * @return the content of the resource if found.
     * @throws name.didier.david.test4j.unit.TestResourceException if the resource cannot be found.
     */
    public String asContent(final String pattern) {
        return handler.loadContent(pattern, testInstance, testMethod);
    }

    /**
     * Interpolate the pattern as a relative path, relative to the current test class and method. See
     * {@link name.didier.david.test4j.unit.TestResource}.
     *
     * @param pattern the pattern to interpolate.
     * @return the interpolated pattern as a relative path.
     */
    public String toPath(final String pattern) {
        return handler.toPath(pattern, testInstance, testMethod);
    }

    /**
     * Called before test invocation.
     *
     * @param base the {@link Statement} to be modified.
     * @param method the method to be run.
     * @param target the object on which the method will be run.
     */
    protected void before(Statement base, FrameworkMethod method, Object target) {
        testInstance = target;
        testMethod = method.getMethod();
        handler.inject(testInstance, testMethod);
    }

    /**
     * Called after test invocation.
     *
     * @param base the {@link Statement} to be modified.
     * @param method the method to be run.
     * @param target the object on which the method will be run.
     */
    protected void after(Statement base, FrameworkMethod method, Object target) {
        handler.clear(testInstance, testMethod);
        // testInstance = null;
        // testMethod = null;
    }
}