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JMockit is a Java toolkit for automated developer testing. It contains mocking/faking APIs and a code coverage tool, supporting both JUnit and TestNG. The mocking APIs allow all kinds of Java code, without testability restrictions, to be tested in isolation from selected dependencies.

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/*
 * Copyright (c) 2006 JMockit developers
 * This file is subject to the terms of the MIT license (see LICENSE.txt).
 */
package mockit.internal.startup;

import java.io.*;
import java.lang.instrument.*;
import javax.annotation.*;

import mockit.coverage.*;
import mockit.internal.*;
import mockit.internal.expectations.transformation.*;
import mockit.internal.state.*;
import static mockit.internal.startup.ClassLoadingBridgeFields.createSyntheticFieldsInJREClassToHoldClassLoadingBridges;

/**
 * This is the "agent class" that initializes the JMockit "Java agent". It is not intended for use in client code.
 * Instead, the JVM needs to be initialized with -javaagent:<properPathTo>/jmockit-1-x.jar.
 *
 * @see #premain(String, Instrumentation)
 */
public final class Startup
{
   public static boolean initializing;
   @Nullable private static Instrumentation instrumentation;

   private Startup() {}

   /**
    * This method must only be called by the JVM, to provide the instrumentation object.
    * In order for this to occur, the JVM must be started with "-javaagent:jmockit-1.x.jar" as a command line parameter
    * (assuming the jar file is in the current directory).
    * 

* It is also possible to load user-specified fakes at this time, by having set the "fakes" system property. * * @param agentArgs not used * @param inst the instrumentation service provided by the JVM */ public static void premain(@Nullable String agentArgs, @Nonnull Instrumentation inst) { if (!activateCodeCoverageIfRequested(agentArgs, inst)) { createSyntheticFieldsInJREClassToHoldClassLoadingBridges(inst); instrumentation = inst; initialize(inst); } } private static void initialize(@Nonnull Instrumentation inst) { inst.addTransformer(CachedClassfiles.INSTANCE, true); applyStartupFakes(inst); inst.addTransformer(new ExpectationsTransformer()); } private static void applyStartupFakes(@Nonnull Instrumentation inst) { initializing = true; try { JMockitInitialization.initialize(inst); } finally { initializing = false; } } private static boolean activateCodeCoverageIfRequested(@Nullable String agentArgs, @Nonnull Instrumentation inst) { if ("coverage".equals(agentArgs)) { try { CodeCoverage coverage = CodeCoverage.create(true); inst.addTransformer(coverage); return true; } catch (Throwable t) { try { PrintWriter out = new PrintWriter("coverage-failure.txt"); t.printStackTrace(out); out.close(); } catch (FileNotFoundException ignore) {} } } return false; } @Nonnull @SuppressWarnings("ConstantConditions") public static Instrumentation instrumentation() { return instrumentation; } public static void verifyInitialization() { if (instrumentation == null) { throw new IllegalStateException( "JMockit didn't get initialized; please check the -javaagent JVM initialization parameter was used"); } } @SuppressWarnings("ConstantConditions") public static void retransformClass(@Nonnull Class aClass) { try { instrumentation.retransformClasses(aClass); } catch (UnmodifiableClassException ignore) {} } public static void redefineMethods(@Nonnull ClassIdentification classToRedefine, @Nonnull byte[] modifiedClassfile) { Class loadedClass = classToRedefine.getLoadedClass(); redefineMethods(loadedClass, modifiedClassfile); } public static void redefineMethods(@Nonnull Class classToRedefine, @Nonnull byte[] modifiedClassfile) { redefineMethods(new ClassDefinition(classToRedefine, modifiedClassfile)); } public static void redefineMethods(@Nonnull ClassDefinition... classDefs) { try { //noinspection ConstantConditions instrumentation.redefineClasses(classDefs); } catch (ClassNotFoundException | UnmodifiableClassException e) { throw new RuntimeException(e); // should never happen } catch (InternalError ignore) { // If a class to be redefined hasn't been loaded yet, the JVM may get a NoClassDefFoundError during // redefinition. Unfortunately, it then throws a plain InternalError instead. for (ClassDefinition classDef : classDefs) { detectMissingDependenciesIfAny(classDef.getDefinitionClass()); } // If the above didn't throw upon detecting a NoClassDefFoundError, then ignore the original error and // continue, in order to prevent secondary failures. } } private static void detectMissingDependenciesIfAny(@Nonnull Class mockedClass) { try { Class.forName(mockedClass.getName(), false, mockedClass.getClassLoader()); } catch (NoClassDefFoundError e) { throw new RuntimeException("Unable to mock " + mockedClass + " due to a missing dependency", e); } catch (ClassNotFoundException ignore) { // Shouldn't happen since the mocked class would already have been found in the classpath. } } @Nullable public static Class getClassIfLoaded(@Nonnull String classDescOrName) { String className = classDescOrName.replace('/', '.'); @SuppressWarnings("ConstantConditions") Class[] loadedClasses = instrumentation.getAllLoadedClasses(); for (Class aClass : loadedClasses) { if (aClass.getName().equals(className)) { return aClass; } } return null; } }





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