Rails4: Iteration B2 - generic def for new default valid products

Building on example for "def new_product(image_url)" pg. 101

#a generic method to build new test produce with valid data
#but also allow insertion of any attributes that need to be over-ridden
#takes a hash of attribute values, checks for each and populates default as needed.
#don't add this to real Product, 'cause production code shouldn't provide defaults.
def new_valid_product(data)
Product.new(
:title => data.has_key?(:title) ? data[:title] : "A Book Title",
:description => data.has_key?(:description) ? data[:description] : "ipso lorum... a default description",
:price => data.has_key?(:price) ? data[:price] : 123.45,
:image_url => data.has_key?(:image_url) ? data[:image_url] : "test.gif"
)
end

#a quick test to warn me if any rules change that invalidate the default values.
test "default product attributes are valid" do
product = new_valid_product({})
assert !product.errors[:title].any?, "default title in error"
assert !product.errors[:description].any?, "default_description in error"
assert !product.errors[:price].any?, "default_price in error"
assert !product.errors[:image_url].any?, "default image_url in error"
end

#a quick test to prove to myself that the method accepts input data & uses it correctly.
test "default product attributes can be changed" do
product = new_valid_product({:title => "T", :description => "D", :price => 1, :image_url => "I"})
assert_equal "T", product.title
assert_equal "D", product.description
assert_equal 1, product.price
assert_equal "I", product.image_url
end

Note: My guess it that this kind of method is not really useful, Ruby has fixtures, my suspicion is that in time I'll find it much easier to define and get a fixture, then change a value or two, rather than write this kind of utility method for each model unit test class.