### Question:
ByteSequenceLengthFilter { public String filter(String base) { if ((base == null) || (base.length() < minLength)) { return null; } if (internalIndex >= 0) { return base.substring(0, internalIndex); } int len = base.length(); return base.substring(len + internalIndex, len); } ByteSequenceLengthFilter(int internalIndex, int minLength); String filter(String base); @Override String toString();  }### Answer:
@Test public void testNull() { ByteSequenceLengthFilter bsFilter = new ByteSequenceLengthFilter(1, 1); String result = bsFilter.filter(null); assertEquals(null, result); }
@Test public void testPositiveIndex() { ByteSequenceLengthFilter bsFilter = new ByteSequenceLengthFilter(1, 2); String result = bsFilter.filter("a"); assertEquals(null, result); result = bsFilter.filter("abcd"); assertEquals("ab", result); }
@Test public void testNegativeIndex() { ByteSequenceLengthFilter bsFilter = new ByteSequenceLengthFilter(-1, 2); String result = bsFilter.filter("abcd"); assertEquals("cd", result); }
@Test public void testMinimumLengthZero() { ByteSequenceLengthFilter bsFilter = new ByteSequenceLengthFilter(0, 0); String result = bsFilter.filter("aa"); assertEquals("", result); }