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JMockit is a Java toolkit for developer (unit/integration) testing. It contains mocking APIs and other tools, 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) 2006-2012 Rogério Liesenfeld
 * This file is subject to the terms of the MIT license (see LICENSE.txt).
 */
package mockit.internal.util;

import java.lang.reflect.*;

/**
 * Provides optimized utility methods to extract stack trace information.
 */
public final class StackTrace
{
   private static final Method getStackTraceDepth = getThrowableMethod("getStackTraceDepth");
   private static final Method getStackTraceElement = getThrowableMethod("getStackTraceElement", int.class);

   private static Method getThrowableMethod(String name, Class... parameterTypes)
   {
      Method m;

      try {
         m = Throwable.class.getDeclaredMethod(name, parameterTypes);
      }
      catch (NoSuchMethodException ignore) {
         return null;
      }

      m.setAccessible(true);
      return m;
   }

   private final Throwable t;
   private final StackTraceElement[] elements;

   public StackTrace(Throwable t)
   {
      this.t = t;
      elements = getStackTraceDepth == null ? t.getStackTrace() : null;
   }

   public int getDepth()
   {
      if (elements != null) {
         return elements.length;
      }

      int depth = 0;

      try {
         depth = (Integer) getStackTraceDepth.invoke(t);
      }
      catch (IllegalAccessException ignore) {}
      catch (InvocationTargetException ignored) {}

      return depth;
   }

   public StackTraceElement getElement(int index)
   {
      if (elements != null) {
         return elements[index];
      }

      StackTraceElement element = null;

      try {
         element = (StackTraceElement) getStackTraceElement.invoke(t, index);
      }
      catch (IllegalAccessException ignore) {}
      catch (InvocationTargetException ignored) {}

      return element;
   }

   public static void filterStackTrace(Throwable t)
   {
      StackTrace st = new StackTrace(t);
      int n = st.getDepth();
      StackTraceElement[] filteredST = new StackTraceElement[n];
      int j = 0;

      for (int i = 0; i < n; i++) {
         StackTraceElement ste = st.getElement(i);

         if (ste.getFileName() != null) {
            String where = ste.getClassName();

            if (
               (!where.startsWith("sun.") || ste.isNativeMethod()) &&
               !where.startsWith("org.junit.") && !where.startsWith("junit.") && !where.startsWith("org.testng.")
            ) {
               if (!where.startsWith("mockit.")) {
                  filteredST[j] = ste;
                  j++;
               }
            }
         }
      }

      StackTraceElement[] newStackTrace = new StackTraceElement[j];
      System.arraycopy(filteredST, 0, newStackTrace, 0, j);
      t.setStackTrace(newStackTrace);

      Throwable cause = t.getCause();

      if (cause != null) {
         filterStackTrace(cause);
      }
   }
}