### Question:
Snapshot { public CellBackup getCell(CellId cellId) { if (cellId.getIdManager() != idManager) { throw new IllegalArgumentException(); } return getCell(cellId.cellIndex); } private  Snapshot(IdManager idManager, int snapshotId, Tool tool,
            ImmutableArrayList<CellTree> cellTrees,
            ImmutableArrayList<CellBackup> cellBackups,
            int[] cellGroups, CellId[] groupMainSchematics,
            ImmutableArrayList<LibraryBackup> libBackups,
            Environment environment);  Snapshot(IdManager idManager); Snapshot with(Tool tool, Environment environment, CellBackup[] cellBackupsArray, LibraryBackup[] libBackupsArray); Snapshot with(Tool tool, Environment environment, CellTree[] cellTreesArray, LibraryBackup[] libBackupsArray); Snapshot with(Tool tool, Environment environment); Snapshot withRenamedIds(IdMapper idMapper, CellId fromGroup, String toGroup); List<LibId> getChangedLibraries(Snapshot oldSnapshot); List<CellId> getChangedCells(Snapshot oldSnapshot); Collection<CellId> getCellsDownTop(); CellTree getCellTree(CellId cellId); CellBackup getCell(CellId cellId); CellRevision getCellRevision(CellId cellId); CellTree getCellTree(int cellIndex); CellBackup getCell(int cellIndex); CellRevision getCellRevision(int cellIndex); static CellName makeCellGroupName(Collection<CellName> cellNames); EquivalentSchematicExports getEquivExports(CellId top); ERectangle getCellBounds(CellId cellId); ERectangle getCellBounds(int cellIndex); int getCellGroupIndex(CellId cellId); boolean cellGroupsProbablyChanged(Snapshot that); CellId getMainSchematics(CellId cellId); TechPool getTechPool(); Technology getTech(TechId techId); Artwork getArtwork(); Generic getGeneric(); Schematics getSchematics(); Map<Setting, Object> getSettings(); LibraryBackup getLib(LibId libId); void writeDiffs(IdWriter writer, Snapshot oldSnapshot); static Snapshot readSnapshot(IdReader reader, Snapshot oldSnapshot); void check(); final IdManager idManager; final int snapshotId; final Tool tool; final ImmutableArrayList<CellTree> cellTrees; final ImmutableArrayList<CellBackup> cellBackups; final ImmutableArrayList<LibraryBackup> libBackups; final Environment environment; final TechPool techPool; }### Answer:
@Test public void testGetCell() { System.out.println("getCell"); LibId libId = idManager.newLibId("lib"); CellId cellId = libId.newCellId(CellName.parseName("cellId0;1")); assertEquals(0, cellId.cellIndex); Snapshot instance = initialSnapshot; CellBackup expResult = null; CellBackup result = instance.getCell(cellId); assertEquals(expResult, result); }