### Question:
Datable implements Comparable<Datable>, Serializable, Range { @Override public boolean isValid() { return (fromDate != null) && (toDate != null); } Datable(String edtf); String getEdtf(); boolean isFloruit(); Certainty getCertainty(); Date getFromDate(); Date getToDate(); @Override @JsonValue String toString(); int getFromYear(); int getToYear(); @Override int compareTo(Datable other); @Override boolean equals(Object obj); @Override int hashCode(); @Override boolean isValid(); @Override Object getUpperLimit(); @Override Object getLowerLimit();  }### Answer:
@Test public void testIsValidRange() { assertThat(new Datable("2013").isValid(), is(true)); }
@Test public void testIsValidRangeWithUnknownPattern() { Datable rangeWithoutUnknown = new Datable("unknown"); assertThat(rangeWithoutUnknown.isValid(), is(false)); }