### Question:
MSEmail implements IApplicationData, Serializable { public String getSubject() { return subject; } protected  MSEmail(String subject, MSEmailHeader header, MSEmailBody body, Set<MSAttachement> attachments,
			MSMeetingRequest meetingRequest, MSMessageClass messageClass, MSImportance importance,
			boolean read, boolean starred, boolean answered); static MSEmailBuilder builder(); @Override PIMDataType getType(); MSAddress getDisplayTo(); List<MSAddress> getFrom(); List<MSAddress> getTo(); List<MSAddress> getCc(); List<MSAddress> getReplyTo(); String getSubject(); Date getDate(); MSEmailHeader getHeader(); MSEmailBody getBody(); Set<MSAttachement> getAttachments(); MSMeetingRequest getMeetingRequest(); MSMessageClass getMessageClass(); MSImportance getImportance(); boolean isRead(); boolean isStarred(); boolean isAnswered(); @Override int hashCode(); @Override boolean equals(Object obj);  }### Answer:
@Test public void testMSEmailSubjectNull() { MSEmail msEmail = requirementsInitializedBuilder() .subject(null) .build(); Assertions.assertThat(msEmail.getSubject()).isNull(); }
@Test public void testMSEmailSubjectEmpty() { MSEmail msEmail = requirementsInitializedBuilder() .subject("") .build(); Assertions.assertThat(msEmail.getSubject()).isNull(); }
@Test public void testMSEmailSubjectValue() { MSEmail msEmail = requirementsInitializedBuilder() .subject("a subject") .build(); Assertions.assertThat(msEmail.getSubject()).isEqualTo("a subject"); }