Parse Config File fails if key has a . in it

Hi. I'm trying to parse a /boot/loader.conf file on FreeBSD 12.

One line would be:
its('hw.memtest.tests') { should eq '0' }

Inspec fails with the following error:
undefined method 'memtest' for nil:NilClass

I've tried escaping the dots with a backslash which only changes the error to undefined method 'memtest\' for nil:NilClass

Here's the relevant block:

  options = {
    assignment_regex: /^.+="?.+"?/
  }

  describe parse_config_file('/boot/loader.conf', options) do
    its('aesni_load') { should eq 'YES' }
    its('autoboot_delay') { should eq '-1' }
    its('beastie_disable') { should eq 'YES' }
    its('boot_multicons') { should eq 'YES' }
    its('console') { should eq 'comconsole,vidconsole' }
    its('cc_htcp_load') { should eq 'YES' }
    its('hw.memtest.tests') { should eq '0' }
    its('hw.vtnet.mq_disable') { should eq '0' }
    its('hw.vtnet.mq_max_pairs') { should eq '8' }
    its('kern.geom.label.disk_ident.enable') { should eq '0' }
    its('kern.geom.label.gpt.enable') { should eq '1' }
    its('kern.geom.label.gptid.enable') { should eq '0' }
    its('kern.timecounter.hardware') { should eq 'ACPI-safe' }
    its('intpm_load') { should eq 'YES' }
    its('loader_logo') { should eq 'none' }
    its('mac_ntpd_load') { should eq 'YES' }
    its('machdep.hyperthreading_allowed') { should eq '0' }
    its('nvme_load') { should eq 'YES' }
    its('nullfs_load') { should eq 'YES' }
    its('tmpfs_load') { should eq 'YES' }
    its('vfs.root.mountfrom') { should eq 'zfs:zroot/ROOT/default' }
    its('zfs_load') { should eq 'YES' }
    its('zfs_cache_load') { should eq 'YES' }
    its('zfs_cache_type') { should eq '/etc/zfs/zpool.cache' }
    its('zfs_cache_name') { should eq '/etc/zfs/zpool.cache' }
  end
end

I can see from the following lines in parse_config_test.rb that dots in keys are supported (at least I think that's what I'm seeing; I'm not Ruby literate).

  it 'verify parse_config_file resource' do
    options = {
      assignment_regex: /^\s*([^=]*?)\s*=\s*(.*?)\s*$/
    }
    resource = MockLoader.new(:centos6).load_resource('parse_config_file', '/etc/sysctl.conf', options)
    result = {"kernel.domainname"=>"example.com"}
    _(resource.params).must_equal result
    _(resource.send('kernel.domainname')).must_equal 'example.com'

I'm using Inspec version 4.3.2 and ruby 2.5.5