Rails units testing: No route matches why? - ruby-on-rails

Question

I'm trying to do some units test, this is my first time.
I don't really understand why there is No route matches.
When i run $ rake test test/controllers/products_controller_test.rb
i get this in the output of the console:
1) Error:
ProductsControllerTest#test_should_get_edit:
ActionController::UrlGenerationError: No route matches {:action=>"edit", :controller=>"products"}
test/controllers/products_controller_test.rb:20:in `block in <class:ProductsControllerTest>'
2) Error:
ProductsControllerTest#test_should_get_show:
ActionController::UrlGenerationError: No route matches {:action=>"show", :controller=>"products"}
test/controllers/products_controller_test.rb:35:in `block in <class:ProductsControllerTest>'
3) Error:
ProductsControllerTest#test_should_get_create:
ActionController::ParameterMissing: param is missing or the value is empty: product
app/controllers/products_controller.rb:59:in 'product_params'
app/controllers/products_controller.rb:18:in 'create'
test/controllers/products_controller_test.rb:15:in `block in <class:ProductsControllerTest>'
4) Error:
ProductsControllerTest#test_should_get_update:
ActionController::UrlGenerationError: No route matches {:action=>"update", :controller=>"products"}
test/controllers/products_controller_test.rb:25:in `block in <class:ProductsControllerTest>'
5) Error:
ProductsControllerTest#test_should_get_destroy:
ActionController::UrlGenerationError: No route matches {:action=>"destroy", :controller=>"products"}
test/controllers/products_controller_test.rb:30:in `block in <class:ProductsControllerTest>'
7 runs, 2 assertions, 0 failures, 5 errors, 0 skips
This is the products_controller_test.rb file:
require 'test_helper'
class ProductsControllerTest < ActionController::TestCase
test "should get index" do
get :index
assert_response :success
end
test "should get new" do
get :new
assert_response :success
end
test "should get create" do
get :create
assert_response :success
end
test "should get edit" do
get :edit
assert_response :success
end
test "should get update" do
get :update
assert_response :success
end
test "should get destroy" do
get :destroy
assert_response :success
end
test "should get show" do
get :show
assert_response :success
end
end
routes.rb file:
Rails.application.routes.draw do
resources :products
end

Answer 1

For all these routes (edit, update, destroy), you need to say which product you're editing/updating/destroying. If Rails doesn't know it, it can't draw the route for you.
For edit, for example, the full route would be products/:product_id/edit. So Rails will need to 'fill in' the :product_id key. If you leave it blank the route breaks.
In your code, then, if you're calling get :edit, you need to specify a product id. Like so:
get :edit, product_id: products(:test_product).id
(using the fixtures explained in the Rails test tutorial here)