How to make sure TestNG runs methods on test classes in succession instead of interleaved?

Question

The situation and the problem

I have several test classes, each with several test methods. All tests use the same test database in the background. Each test class

Answer 1

Even in sequential mode TestNG could interleave test methods from the same suite. It does guarantee the sequence @BeforeClass -> @Test -> @AfterClass but it can do something like:

before class1
    test class1.method1
before class2
    test class2.method1
    test class1.method2
after class1
    test class2.method2
after class2

The solution is to force each class in a different suite (which are executed truly sequentially). As of version 2.16, the maven surefire plugin puts each class in a separate suite so the problem is fixed.

On the other hand, IDEA (even the latest 13 EAP) generates an xml file with all classes in the same suite. Hopefully IDEA will follow suit and fix this too. Interleaved tests are a showstopper when working with shared resources such as databases.