This commits improves the test coverage for
ManageSubscriptionFormRenderer by creating two custom fields for the
test subscriber and checking that those custom fields are included in
the output returned by ManageSubscriptionFormRenderer::renderForm().
[MAILPOET-4020]
The test class ManageSubscriptionFormRendererTest creates a subscriber
with a segment. But when calling $this->formRenderer->renderForm(), it
was passing the subscriber without information about its segments. This
meant that the output returned by renderForm() wrongly had the list of
segments without the subscriber segment checked.
This commit fixes this problem by passing the subscriber with the
segments to renderForm() and changing the expected HTML that should be
returned.
[MAILPOET-4020]
