### Question:
VcfGenotypeData extends AbstractRandomAccessGenotypeData implements SampleVariantsProvider { @Override public List<String> getSeqNames() { return new ArrayList<String>(tabixIndex.getSeqNames()); } VcfGenotypeData(File bzipVcfFile, int cacheSize, double minimumPosteriorProbabilityToCall);  VcfGenotypeData(File bzipVcfFile, File tabixIndexFile, double minimumPosteriorProbabilityToCall);  VcfGenotypeData(File bzipVcfFile, File tabixIndexFile, int cacheSize, double minimumPosteriorProbabilityToCall); @Override Iterator<GeneticVariant> iterator(); @Override List<Alleles> getSampleVariants(final GeneticVariant variant); @Override Map<String, Annotation> getVariantAnnotationsMap(); @Override List<Sequence> getSequences(); @Override List<Sample> getSamples(); @Override int cacheSize(); @Override List<Boolean> getSamplePhasing(GeneticVariant variant); @Override boolean arePhasedProbabilitiesPresent(GeneticVariant variant); @Override int getSampleVariantProviderUniqueId(); @Override Map<String, SampleAnnotation> getSampleAnnotationsMap(); @Override byte[] getSampleCalledDosage(GeneticVariant variant); @Override float[] getSampleDosage(GeneticVariant variant); @Override void close(); @Override boolean isOnlyContaingSaveProbabilityGenotypes(); @Override float[][] getSampleProbilities(GeneticVariant variant); @Override double[][] getSampleProbabilitiesComplex(GeneticVariant variant); @Override double[][][] getSampleProbabilitiesPhased(GeneticVariant variant); @Override FixedSizeIterable<GenotypeRecord> getSampleGenotypeRecords(GeneticVariant variant); @Override List<String> getSeqNames(); @Override Iterable<GeneticVariant> getSequenceGeneticVariants(String seqName); @Override Iterable<GeneticVariant> getVariantsByPos(final String seqName, final int startPos); @Override GeneticVariant getSnpVariantByPos(String seqName, int startPos); @Override Iterable<GeneticVariant> getVariantsByRange(final String seqName, final int rangeStart, final int rangeEnd); MappedGenotypeField getPreferredGenotypeField(); void setPreferredGenotypeField(String preferredGenotypeField);  }### Answer:
@Test public void getSeqNames() { List<String> seqNames = genotypeData.getSeqNames(); assertNotNull(seqNames); assertEquals(seqNames.size(), 3); assertEquals(seqNames.get(0), "1"); assertEquals(seqNames.get(1), "2"); assertEquals(seqNames.get(2), "3"); }