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How to test that an error does not occur?

I am starting to implement testing for an R package, and have been using the testthat package. Note that I am new to testing, so perhaps my approach is off.

I have a function that currently fails the 16th time it is executed, and before fixing this, I want to write a regression test that will catch it if it re-appears.

e.g., the following always throws the same error message:

 for i in (1:17) myfun()

myfun does not return anything, it only has a side-effect of opening a database connection. It is clear to me that I can write a test that expects an error and passes if it is returned:

 expect_error(for (i in 1:17) myfun()) 

But I don't quite get how to write a test to ensure that the error does not occur. As it is not obvious, perhaps my approach is wrong. I can figure out how to write more specific tests, but I would like to start with this one.

What type of test would I write to make sure that such an error does not appear?