### Question:
Identifiers { public static Identifier truncatePath(Identifier base, int start) { return transformer(base).truncatePath(start).apply(); } private  Identifiers(); static Identifier withNamespace(Identifier base, String namespace); static Identifier withPath(Identifier base, String path); static Identifier prefixPath(Identifier base, String prefix); static Identifier suffixPath(Identifier base, String suffix); static Identifier truncatePath(Identifier base, int start); static Identifier truncatePath(Identifier base, int start, int end); static Identifier replacePathSegments(Identifier base, int start, int end, String replacement); static Identifier remove(Identifier base, int start, int end); static IdentifierTransformer transformer(Identifier base);  }### Answer:
@Test void truncatePathStartOnly() { Identifier base = new Identifier("foo:bar/baz/qux"); assertEquals(new Identifier("foo:baz/qux"), Identifiers.truncatePath(base, 1)); assertThrows(IndexOutOfBoundsException.class, () -> Identifiers.truncatePath(base, -1), "Negative start index did not cause exception!"); assertThrows(IndexOutOfBoundsException.class, () -> Identifiers.truncatePath(base, 3), "Start index > segment count did not cause exception!"); }
@Test void truncatePathStartEnd() { Identifier base = new Identifier("foo:bar/baz/qux"); assertEquals(new Identifier("foo:baz"), Identifiers.truncatePath(base, 1, 2)); assertThrows(IndexOutOfBoundsException.class, () -> Identifiers.truncatePath(base, -1, 2), "Negative start index did not cause exception!"); assertThrows(IndexOutOfBoundsException.class, () -> Identifiers.truncatePath(base, 1, 4), "End index > segment count did not cause exception!"); assertThrows(IllegalArgumentException.class, () -> Identifiers.truncatePath(base, 2, 1), "Start index > end index did not cause exception!"); }