Formatting output so that Intellij Idea shows diffs for two texts

Question

I would like to be able to print in the logs a message for which intellij idea would present a nice way of comparing two objects (strings). This happens automatically for the er

Answer 1

IntelliJ IDEA is using the hardcoded regular expression. If the text matches the pattern, it will suggest to click to view the difference.

The pattern is:

expected: but was:

Output should match the format of assertEquals or assertThat.

The exact patterns are somewhat scattered around the code in IDEA, but some are e.g. here.