src/main/java/org/fest/assertions/ThrowableAssert.java
public @NotNull ThrowableAssert isInstanceOf(@NotNull Class<? extends Throwable> type) {
    objectAssert.isInstanceOf(type);
    return this;
  }
public @NotNull ThrowableAssert isInstanceOf(@NotNull Class<? extends Throwable> type) {
    objectAssert.isInstanceOf(type);
    return this;
  }
Verifies that the actual {@code Throwable} is an instance of the given type.

@param type the type to check the actual {@code Throwable} against.
@return this assertion object.
@throws AssertionError       if the actual {@code Throwable} is {@code null}.
@throws AssertionError       if the actual {@code Throwable} is not an instance of the given type.
@throws NullPointerException if the given type is {@code null}.