Add a test to ensure that modifying then removing an attribute results in a DELETE

Author: candrews

spring-session-jdbc/src/test/java/org/springframework/session/jdbc/JdbcOperationsSessionRepositoryTests.java

@@ -467,6 +467,25 @@ public void saveUpdatedAddThenRemoveSingleAttribute() {
 		verifyZeroInteractions(this.jdbcOperations);
 	}
 
+	@Test
+	public void saveUpdatedModifyThenRemoveSingleAttribute() {
+		JdbcOperationsSessionRepository.JdbcSession session = this.repository.new JdbcSession("primaryKey",
+				new MapSession());
+		session.setAttribute("testName", "testValue");
+		session.clearChangeFlags();
+		session.setAttribute("testName", "testValueModifed");
+		session.removeAttribute("testName");
+
+		this.repository.save(session);
+
+		assertThat(session.isNew()).isFalse();
+		assertPropagationRequiresNew();
+		verify(this.jdbcOperations, times(1)).update(
+				startsWith("DELETE FROM SPRING_SESSION_ATTRIBUTES WHERE"),
+				isA(PreparedStatementSetter.class));
+		verifyZeroInteractions(this.jdbcOperations);
+	}
+
 	@Test
 	public void saveUpdatedRemoveThenModifySingleAttribute() {
 		JdbcOperationsSessionRepository.JdbcSession session = this.repository.new JdbcSession("primaryKey",