src/main/java/org/fest/assertions/FileAssert.java
public @NotNull FileAssert hasSize(long expected) {
    isNotNull();
    long size = actual.length();
    if (size == expected) {
      return this;
    }
    failIfCustomMessageIsSet();
    throw failure(format("size of file:<%s> expected:<%s> but was:<%s>", actual, expected, size));
  }
public @NotNull FileAssert hasSize(long expected) {
    isNotNull();
    long size = actual.length();
    if (size == expected) {
      return this;
    }
    failIfCustomMessageIsSet();
    throw failure(format("size of file:<%s> expected:<%s> but was:<%s>", actual, expected, size));
  }
Verifies that the size of the actual {@code File} is equal to the given one.

@param expected the expected size of the actual {@code File}.
@return this assertion object.
@throws AssertionError if the the actual {@code File} is {@code null}.
@throws AssertionError if the size of the actual {@code File} is not equal to the given one.