test: improve test locality

[nicktorwald]

At least, we need to increase test locality moving arrange-act-assert pattern within one test method or at most in one test class for the reused arrangements (@ before / @ after).

An example of a test class structure:

@DisplayName("A resultSet")
class SelectOperationIT {
    
    // text fixture
    Statement statement;
    ...

    // reused for each test preparations
    @BeforeEach
    public void setUp() throws Exception {
        statement.executeUpdate("CREATE TABLE test (id INT PRIMARY KEY, val VARCHAR(50))");
    }

    // cleanup garbage after the test execution
    @AfterEach
    public void tearDown() throws Exception {
        statement.executeUpdate("DROP TABLE test");
    }

    @Test
    @DisplayName("fetched one row by id = 1")
    public void testOneRowSelect() {
        // arrange (given)
        String insertQuery = "INSERT INTO test VALUES (1, 'a');
        statement.executeUpdate(insertQuery);
        
        // act (when)
        String selectQuery = "SELECT * FROM test WHERE id = 1";	
        ResultSet resultSet = statement.executeUpdate(selectQuery);
        resultSet.next();
    
        // assert (then)
        int expectedResultId = 1;
        String expectedResultValue = "a";
        assertEquals(expectedResultId, result.getInt(1));
        assertEquals(expectedResultValue, result.getString(2));
    }

     ...
}

[nicktorwald]

@Totktonada any extra thoughts about it?

[Totktonada]

Agreed. No, I have no extra thoughts.