### Question:
BillFormat implements Serializable { @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; BillFormat that = (BillFormat) o; return outputSize == that.outputSize && language == that.language && separatorType == that.separatorType && Objects.equals(fontFamily, that.fontFamily) && graphicsFormat == that.graphicsFormat && resolution == that.resolution; } BillFormat();  BillFormat(BillFormat format); OutputSize getOutputSize(); void setOutputSize(OutputSize outputSize); Language getLanguage(); void setLanguage(Language language); SeparatorType getSeparatorType(); void setSeparatorType(SeparatorType separatorType); String getFontFamily(); void setFontFamily(String fontFamily); GraphicsFormat getGraphicsFormat(); void setGraphicsFormat(GraphicsFormat graphicsFormat); int getResolution(); void setResolution(int resolution); @Override boolean equals(Object o); @Override int hashCode(); @Override String toString();  }### Answer:
@Test void testEquals() { BillFormat format1 = new BillFormat(); BillFormat format2 = new BillFormat(); assertEquals(format1, format2); assertEquals(format1, format2); format2.setOutputSize(OutputSize.A4_PORTRAIT_SHEET); assertNotEquals(format1, format2); }