### Question:
Context implements Externalizable, Loggeable, Pausable, Cloneable { public void writeExternal (ObjectOutput out) throws IOException { out.writeByte (0); Set s = getPMap().entrySet(); out.writeInt (s.size()); Iterator iter = s.iterator(); while (iter.hasNext()) { Map.Entry entry = (Map.Entry) iter.next(); out.writeObject(entry.getKey()); out.writeObject(entry.getValue()); } } Context(); void put(Object key, Object value); void put(Object key, Object value, boolean persist); void persist(Object key); void evict(Object key); T get(Object key); T get(Object key, T defValue); synchronized T remove(Object key); String getString(Object key); String getString(Object key, String defValue); void dump(PrintStream p, String indent); @SuppressWarnings("unchecked") synchronized T get(Object key, long timeout); void writeExternal(ObjectOutput out); void readExternal(ObjectInput in); @Override Context clone(); @Override boolean equals(Object o); @Override int hashCode(); synchronized Map<Object,Object> getMap(); synchronized LogEvent getLogEvent(); synchronized Profiler getProfiler(); synchronized Result getResult(); void log(Object msg); void checkPoint(String detail); void setPausedTransaction(PausedTransaction p); PausedTransaction getPausedTransaction(); PausedTransaction getPausedTransaction(long timeout); void setTimeout(long timeout); long getTimeout(); synchronized void resume(); boolean isTrace(); void setTrace(boolean trace);  }### Answer:
@Test public void testWriteExternal1() throws Throwable { Context context = new Context(); context.writeExternal(new ObjectOutputStream(new ByteArrayOutputStream())); }
@Test public void testWriteExternalThrowsNullPointerException() throws Throwable { Context context = new Context(); try { context.writeExternal(null); fail("Expected NullPointerException to be thrown"); } catch (NullPointerException ex) { if (isJavaVersionAtMost(JAVA_14)) { assertNull(ex.getMessage(), "ex.getMessage()"); } else { assertEquals("Cannot invoke \"java.io.ObjectOutput.writeByte(int)\" because \"out\" is null", ex.getMessage(), "ex.getMessage()"); } } }