Rails, ActionController::UnknownFormat when testing a post (create) request - ruby-on-rails

Question

I am testing my rails application and so far this test is failing all the others pass.
The test is as follows:
test "should create broadcast" do
assert_difference('Broadcast.count') do
post :create, broadcast: { title: "title", content: "content", user_id: #broadcast.user_id}
end
assert_redirected_to broadcast_path(assigns(:broadcast))
end
and the controller has this snippet:
feed_result = []
if params.has_key?(:feeds)
feed_result = params[:feeds]
else
feed_result = ["None"]
end
if #broadcast.save
# Only after saving do we try and do the real broadcast. Could have been
# done using an observer, but I wanted this to be more explicit
results = BroadcastService.broadcast(#broadcast, feed_result)
if results.length > 0
# Something went wrong when trying to broadcast to one or more of the
# feeds.
#broadcast.errors[:base] << ("#{I18n.t('broadcasts.unable-message')}: #{results.inspect}")
flash[:error] = I18n.t('broadcasts.saved-but-message')
else
flash[:notice] = I18n.t('broadcasts.saved-message')
no_errors = true
end
if no_errors
format.html { redirect_to(broadcasts_url(page: #current_page)) }
format.json { render json: #broadcast, status: :created, location: #broadcast }
else
format.html { render :new }
format.xml {
# Either say it partly worked but send back the errors or else send
# back complete failure indicator (couldn't even save)
if results
render json: #broadcast.errors, status: :created, location: #broadcast
else
render json: #broadcast.errors, status: :unprocessable_entity
end
}
end
end
end
I have left out information that is unnecessary. it must be noted that if i am not running a test, and i am in fact running the live server this create method functions as expected and no error is thrown.
i have tried the following:
post :create, broadcast: { title: "title", content: "content", user_id: #broadcast.user_id, format: :html}
post :create, broadcast: { title: "title", content: "content", user_id: #broadcast.user_id, format: :json}
post :create, broadcast: { title: "title", content: "content", user_id: #broadcast.user_id, format: 'html'}
post :create, broadcast: { title: "title", content: "content", user_id: #broadcast.user_id, format: 'json'}
And the error persists.
If anyone has any ideas, id love to hear them!
Thanks,
Chris.