public class PreconditionsTest extends TestCase {
  public void testCheckArgument_simple_success() {
    checkArgument(true);
  }

  public void testCheckArgument_simple_failure() {
    assertThrows(IllegalArgumentException.class, () -> checkArgument(false));
  }

  public void testCheckArgument_simpleMessage_success() {
    checkArgument(true, IGNORE_ME);
  }

  public void testCheckArgument_simpleMessage_failure() {

    abstract T returningT();

    abstract void acceptT(T t);

    abstract <X extends T> X returningX();

    abstract <X> void acceptX(X x);

    abstract <T2 extends Enum<T2> & CharSequence> T2 returningT2();

    abstract <T2 extends CharSequence & Iterable<T2>> void acceptT2(T2 t2);

    static void verifyConsistentRawType() {

    assertFailsToDecode(base64(), "?", "Invalid input length 1");
  }

  public void testBase64CannotUpperCase() {
    assertThrows(IllegalStateException.class, () -> base64().upperCase());
  }

  public void testBase64CannotLowerCase() {
    assertThrows(IllegalStateException.class, () -> base64().lowerCase());
  }

  public void testBase64CannotIgnoreCase() {

    }
  }

  public void testTailClosedEntrySet() {
    testSubMultisetEntrySet(SubMultisetSpec.TAIL_CLOSED);
  }

  public void testTailClosedSize() {
    testSubMultisetSize(SubMultisetSpec.TAIL_CLOSED);
  }

  public void testTailClosedDistinctElements() {
    testSubMultisetDistinctElements(SubMultisetSpec.TAIL_CLOSED);
  }

  public void testTailOpenEntrySet() {

  }

  public void testPrependTwoElements() {
    String[] result = ObjectArrays.concat("foo", new String[] {"bar", "baz"});
    assertThat(result).asList().containsExactly("foo", "bar", "baz").inOrder();
  }

  public void testAppendZeroElements() {
    String[] result = ObjectArrays.concat(new String[] {}, "foo");
    assertThat(result).asList().contains("foo");
  }

  public void testAppendOneElement() {

            }

            @Override
            public void setCharacterEncoding(String charset) {
            }

            @Override
            public void setContentLength(int len) {
            }

            @Override
            public void setContentLengthLong(long len) {
            }

            @Override
            public void setContentType(String type) {
            }

@NullUnmarked
public class FuturesGetCheckedTest extends TestCase {
  // Boring untimed-get tests:

  public void testGetCheckedUntimed_success() throws TwoArgConstructorException {
    assertEquals("foo", getChecked(immediateFuture("foo"), TwoArgConstructorException.class));
  }

  public void testGetCheckedUntimed_interrupted() {
    SettableFuture<String> future = SettableFuture.create();
    Thread.currentThread().interrupt();

        @Override
        public void execute(Runnable command) {}
      };
    }

    @Override
    protected void run() throws Exception {}
  }

  public void testStopWhileStarting_runNotCalled() throws Exception {
    CountDownLatch started = new CountDownLatch(1);
    FakeService service =
        new FakeService() {
          @Override
          protected void startUp() throws Exception {

    }
  }

  public void testFloorPowerOfTwoNegative() {
    for (long x : NEGATIVE_LONG_CANDIDATES) {
      assertThrows(IllegalArgumentException.class, () -> LongMath.floorPowerOfTwo(x));
    }
  }

  public void testCeilingPowerOfTwoZero() {
    assertThrows(IllegalArgumentException.class, () -> LongMath.ceilingPowerOfTwo(0L));
  }

  public void testFloorPowerOfTwoZero() {

para JSON, utilizando o mesmo[Codificador Compatível com JSON](../tutorial/encoder.md){.internal-link target=_blank} explicado no tutorial. Isso permite que você retorne **objetos abstratos**, como modelos do banco de dados, por exemplo.

Mas se você tem certeza que o conteúdo que você está retornando é **serializável com JSON**, você pode passá-lo diretamente para a classe de resposta e evitar o trabalho extra que o FastAPI teria ao passar o conteúdo pelo `jsonable_encoder` antes de passar...