### Question:
UnionDB extends CompositeDB implements Union { @Override public void replaceWith(DataType dataType) { if (!(dataType instanceof Union)) { throw new IllegalArgumentException(); } lock.acquire(); boolean isResolveCacheOwner = dataMgr.activateResolveCache(); try { checkDeleted(); doReplaceWith((Union) dataType, true); } catch (DataTypeDependencyException e) { throw new IllegalArgumentException(e.getMessage(), e); } finally { if (isResolveCacheOwner) { dataMgr.flushResolveQueue(true); } lock.release(); } } UnionDB(DataTypeManagerDB dataMgr, DBObjectCache<DataTypeDB> cache,
			CompositeDBAdapter compositeAdapter, ComponentDBAdapter componentAdapter,
			Record record); @Override String getRepresentation(MemBuffer buf, Settings settings, int length); @Override boolean isNotYetDefined(); @Override DataTypeComponent add(DataType dataType, int length, String componentName,
			String comment); @Override DataTypeComponent insert(int ordinal, DataType dataType, int length, String name,
			String comment); @Override DataTypeComponent addBitField(DataType baseDataType, int bitSize, String componentName,
			String comment); @Override DataTypeComponent insertBitField(int ordinal, DataType baseDataType, int bitSize,
			String componentName, String comment); @Override void delete(int ordinal); @Override void delete(int[] ordinals); @Override void replaceWith(DataType dataType); @Override boolean isPartOf(DataType dataType); @Override int getNumComponents(); @Override int getNumDefinedComponents(); @Override DataTypeComponent getComponent(int ordinal); @Override DataTypeComponentDB[] getComponents(); @Override DataTypeComponentDB[] getDefinedComponents(); @Override DataType copy(DataTypeManager dtm); @Override DataType clone(DataTypeManager dtm); @Override int getLength(); @Override void dataTypeSizeChanged(DataType dt); @Override void dataTypeAlignmentChanged(DataType dt); @Override void dataTypeDeleted(DataType dt); @Override boolean isEquivalent(DataType dataType); @Override void dataTypeReplaced(DataType oldDt, DataType newDt); @Override void dataTypeNameChanged(DataType dt, String oldName); @Override boolean dependsOn(DataType dt); @Override String getDefaultLabelPrefix(); @Override void realign(); @Override void adjustInternalAlignment(boolean notify);  }### Answer:
@Test public void testReplaceWith() throws InvalidDataTypeException { assertEquals(4, union.getLength()); assertEquals(4, union.getNumComponents()); Union newUnion = createUnion("Replaced"); newUnion.setDescription("testReplaceWith()"); newUnion.insert(0, new DWordDataType(), 4, "field2", null); newUnion.insert(0, new WordDataType(), 2, null, "Comment2"); newUnion.insert(0, new ByteDataType(), 1, "field0", "Comment1"); newUnion.addBitField(IntegerDataType.dataType, 4, "MyBit1", "bitComment1"); newUnion.addBitField(IntegerDataType.dataType, 3, "MyBit2", "bitComment2"); CompositeTestUtils.assertExpectedComposite(this, "/Replaced\n" + "Unaligned\n" + "Union Replaced {\n" + " 0 byte 1 field0 \"Comment1\"\n" + " 0 word 2 null \"Comment2\"\n" + " 0 dword 4 field2 \"\"\n" + " 0 int:4(0) 1 MyBit1 \"bitComment1\"\n" + " 0 int:3(0) 1 MyBit2 \"bitComment2\"\n" + "}\n" + "Size = 4 Actual Alignment = 1", newUnion); union.replaceWith(newUnion); CompositeTestUtils.assertExpectedComposite(this, "/TestUnion\n" + "Unaligned\n" + "Union TestUnion {\n" + " 0 byte 1 field0 \"Comment1\"\n" + " 0 word 2 null \"Comment2\"\n" + " 0 dword 4 field2 \"\"\n" + " 0 int:4(0) 1 MyBit1 \"bitComment1\"\n" + " 0 int:3(0) 1 MyBit2 \"bitComment2\"\n" + "}\n" + "Size = 4 Actual Alignment = 1", union); assertEquals("", union.getDescription()); }