*
   * <p>If the dataset contains any non-finite values ({@link Double#POSITIVE_INFINITY}, {@link
   * Double#NEGATIVE_INFINITY}, or {@link Double#NaN}) then the result is {@link Double#NaN}.
   *
   * @throws IllegalStateException if the dataset is empty
   */
  public double populationCovariance() {
    checkState(count() != 0);
    return sumOfProductsOfDeltas / count();
  }

  /**

[Mockito](https://github.com/mockito/mockito):

1. Script the mocks.
2. Run application code.
3. Verify that the expected requests were made.

Here's a complete example:

```java
public void test() throws Exception {
  // Create a MockWebServer. These are lean enough that you can create a new
  // instance for every unit test.
  MockWebServer server = new MockWebServer();

  // Schedule some responses.

   * message otherwise.
   *
   * @throws VerifyException if {@code expression} is {@code false}
   * @see Preconditions#checkState Preconditions.checkState()
   */
  public static void verify(boolean expression) {
    if (!expression) {
      throw new VerifyException();
    }
  }

  /**

        }
    }

    public static void store( OutputStream out, String header ) throws IOException {
        prp.store( out, header );
    }

    /**
     * List the properties in the <code>Code</code>.
     */

    public static void list( PrintStream out ) throws IOException {
        prp.list( out );
    }

    /**
     * Add a property.
     */

    return new LinkedBlockingDeque<>();
  }

  /**
   * Creates an empty {@code LinkedBlockingDeque} with the given (fixed) capacity.
   *
   * @throws IllegalArgumentException if {@code capacity} is less than 1
   * @since 12.0
   */
  @J2ktIncompatible
  @GwtIncompatible // LinkedBlockingDeque

        @Override
        public FileVisitResult preVisitDirectory(final Path dir, final BasicFileAttributes attrs) throws IOException {
            return FileVisitResult.CONTINUE;
        }

        @Override
        public FileVisitResult visitFile(final Path file, final BasicFileAttributes attrs) throws IOException {

    for (int i = 0; i < reps; i++) {
      tmp += System.identityHashCode(encoding.encoding.decode(decodingInputs[i & INPUTS_MASK]));
    }
    return tmp;
  }

  @Benchmark
  public int encodingStream(int reps) throws IOException {
    int tmp = 0;
    for (int i = 0; i < reps; i++) {
      StringWriter target = new StringWriter(2 * n);
      OutputStream encodingStream = encoding.encoding.encodingStream(target);

        super(messageBuilderFactory, secDispatcher);
    }

    @Override
    public int execute(DefaultEncryptInvoker.LocalContext context) throws Exception {
        if (!validateConfiguration(context)) {
            context.terminal
                    .writer()
                    .println(messageBuilderFactory
                            .builder()

```java
class LoggingInterceptor implements Interceptor {
  @Override public Response intercept(Interceptor.Chain chain) throws IOException {
    Request request = chain.request();

    long t1 = System.nanoTime();
    logger.info(String.format("Sending request %s on %s%n%s",
        request.url(), chain.connection(), request.headers()));

   */
  @Test
  public void testNulls() throws Exception {
    for (Class<?> classToTest : findClassesToTest(loadClassesInPackage(), NULL_TEST_METHOD_NAMES)) {
      if (classToTest.getSimpleName().equals("ReflectionFreeAssertThrows")) {
        /*
         * These classes handle null properly but throw IllegalArgumentException for the default