I just started using this IntelliJ plugin and really like it: https://plugins.jetbrains.com/plugin/10345-assertions2assertj
To install, go to IntelliJ Preferences -> Plugins -> Marketplace. Search for "Assertions2Assertj" and Install it. You'll have to restart IntelliJ before you can use it. To use, just right-click anywhere within a test class and select Refactor -> Convert Assertions to AssertJ -> Convert current file. You'll still need to manually convert try-fail-catch blocks to use catchThrowable or assertThatThrownBy. You should also review any assertions that are automatically converted. -Kirk
