bats: source script with failing command

I want to test this functions.sh:

#!/usr/bin/env bash

function func {
    false # bats should ignore this
    return 0
}

with this unit test:

#!/usr/bin/env bats

@test "test func" {
    source ./functions.sh
    func
}

bats fails with

 ✗ test func
   (from function `func' in file ./functions.sh, line 4,
    in test file test.sh, line 5)
     `func' failed

though, despite the function returning 0.

How can I source a script, which has functions with lines, which fail? Instead of false, it could be a test with grep.

I found a solution, here is a related question.

Since bats runs with -e, the sourcing immediately fails, if a line in the sourced script fails.

To solve this, you can either wrap the failing command with if ...;then
or assign it with F=$(...) || true.

functions.sh looks like this now:

#!/usr/bin/env bash

function func {
    if ! false; then
        echo "false"
    fi
    F=$(false) || true
    return 0
}

Docs: https://manpages.org/set

Thanks to larsks for hinting the solution!