### Question:
BidMachine { public static void setPublisher(@Nullable Publisher publisher) { BidMachineImpl.get().setPublisher(publisher); }  static void initialize(@NonNull Context context, @NonNull String sellerId); static void initialize(@NonNull Context context,
                                  @NonNull String sellerId,
                                  @Nullable InitializationCallback callback); static boolean isInitialized(); static void setEndpoint(@NonNull String url); static void setLoggingEnabled(boolean enabled); static void setTestMode(boolean testMode); static void setTargetingParams(@Nullable TargetingParams targetingParams); static void setConsentConfig(boolean hasConsent, @Nullable String consentString); static void setSubjectToGDPR(@Nullable Boolean subject); static void setCoppa(@Nullable Boolean coppa); static void setPublisher(@Nullable Publisher publisher); static void registerNetworks(@NonNull NetworkConfig... networkConfigs); static void registerNetworks(@NonNull String jsonData); static void registerAdRequestListener(@NonNull AdRequest.AdRequestListener adRequestListener); static void unregisterAdRequestListener(@NonNull AdRequest.AdRequestListener adRequestListener); static final String NAME; static final String VERSION; static final int VERSION_CODE; }### Answer:
@Test public void setPublisher() { assertNull(BidMachineImpl.get().getPublisher()); Publisher publisher = new Publisher.Builder().build(); BidMachine.setPublisher(publisher); assertNotNull(BidMachineImpl.get().getPublisher()); assertEquals(publisher, BidMachineImpl.get().getPublisher()); BidMachine.setPublisher(null); assertNull(BidMachineImpl.get().getPublisher()); }