EditableStub implements Editable { @Override public Editable append(CharSequence text) { value.append(text); return this; } EditableStub(String s); @Override Editable replace(int st, int en, CharSequence source, int start, int end); @Override Editable replace(int st, int en, CharSequence text); @Override Editable insert(int where, CharSequence text, int start, int end); @Override Editable insert(int where, CharSequence text); @Override Editable delete(int st, int en); @Override Editable append(CharSequence text); @Override Editable append(CharSequence text, int start, int end); @Override Editable append(char text); @Override void clear(); @Override void clearSpans(); @Override void setFilters(InputFilter[] filters); @Override InputFilter[] getFilters(); @Override void getChars(int start, int end, char[] dest, int destoff); @Override void setSpan(Object what, int start, int end, int flags); @Override void removeSpan(Object what); @Override T[] getSpans(int start, int end, Class<T> type); @Override int getSpanStart(Object tag); @Override int getSpanEnd(Object tag); @Override int getSpanFlags(Object tag); @Override int nextSpanTransition(int start, int limit, Class type); @Override int length(); @Override char charAt(int index); @Override CharSequence subSequence(int start, int end); @Override String toString();  }
@Test public void append() { assertThat(tested.append("ed").toString()).isEqualTo("tested"); }