### Question:
ColumnVector { public void normalize() { this.matrix.normalizeColumns(); } ColumnVector(final int size);  ColumnVector(final double... vector); private  ColumnVector(final Matrix matrix); int size(); double getAt(final int index); void setAt(final int index, final double val); void incrementAt(final int index, final double val); void normalize(); void scale(final double scale); ColumnVector multiplyElementWise(final ColumnVector vector); ColumnVector addElementWise(final ColumnVector vector); double absSum(); double sum(); ColumnVector roundTo(final int numPlaces); ColumnVector add(final double scalar); ColumnVector multiply(final double scalar); ColumnVector sqrt(); ColumnVector abs(); final boolean isZeroVector(); double[] getRaw(); void setAll(final double val); boolean align(); double max(); double median(); double getMagnitude(); double l1Distance(final ColumnVector vector); double l2Distance(final ColumnVector vector); double correlation(final ColumnVector vector); @Override String toString(); void removeNegatives(); @Override int hashCode(); @Override boolean equals(final Object obj);  }### Answer:
@Test public void vectorWithNonZeroSumCanBeNormalized() { final ColumnVector vector = new ColumnVector(3, 5, 2); vector.normalize(); MatcherAssert.assertThat(vector, IsEqual.equalTo(new ColumnVector(0.3, 0.5, 0.2))); }
@Test public void vectorWithNegativeValuesCanBeNormalized() { final ColumnVector vector = new ColumnVector(3, -5, 2); vector.normalize(); MatcherAssert.assertThat(vector, IsEqual.equalTo(new ColumnVector(0.3, -0.5, 0.2))); }
@Test public void zeroVectorCanBeNormalized() { final ColumnVector vector = new ColumnVector(3); vector.normalize(); MatcherAssert.assertThat(vector, IsEqual.equalTo(new ColumnVector(0, 0, 0))); }