Use AssertJ correctly

Spring Framework tests must use AssertJ for assertions rather than JUnit’s Assertions, Spring’s Assert class, or plain assert statements. Follow these AssertJ best practices:

1. Use fluent assertions with proper methods:

   // PREFERRED
   assertThat(collection).hasSize(2);
      
   // AVOID
   assertThat(collection.size()).isEqualTo(2);
   

2. For exception testing, use:

   // PREFERRED
   assertThatExceptionOfType(BadSqlGrammarException.class).isThrownBy(() -> {
       jdbcTemplate.queryForList("SELECT name FROM user", String.class);
   });
      
   // AVOID
   try {
       jdbcTemplate.queryForList("SELECT name FROM user", String.class);
       fail("BadSqlGrammarException should have been thrown");
   }
   catch (BadSqlGrammarException expected) {
   }
   

3. For code that shouldn’t throw exceptions:

   // PREFERRED
   assertThatCode(() -> {
       Assert.noNullElements(asList("foo", "bar"), "enigma");
   }).doesNotThrowAnyException();
      
   // AVOID
   Assert.noNullElements(asList("foo", "bar"), "enigma"); // Missing verification
   

Using AssertJ consistently provides more readable tests, better failure messages, and ensures test consistency throughout the codebase.