I have a Product schema which has a UPI(unique product identifier) eg. A985748BNG6784C . This is an autogenerated unique product identifier.
I have a function upi_generate() which calls another external function gen_nano_id() to generate this random unique id.
If by chance, the id generated by gen_nano_id() has already been generated, the function upi_generate() calls itself recursively till the time gen_nano_id() generates a unique id. Thus generating a unique UPI .
gen_nano_id() can sometimes return duplicate ids and for that purpose I have written the below code with recursive call.
def gen_nano_id() do #external function
Nanoid.generate(10, "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ")
end
# TODO: write test case for this
def upi_generate() do # required function
upi = "A" <> gen_nano_id() <> "C"
case get_product_with_upi(upi) do
nil ->
upi
_ ->
upi_generate()
end
end
# Check if product with upi already exists
defp get_product_with_upi(upi) do
from(p in "snitch_products", select: p.upi, where: p.upi == ^upi)
|> Repo.one()
end
Now, I have to test the id regeneration logic for duplicate ids.
My testing approach involves following logic. Create two products with duplicate UPI and try to reach the _ part of the case comparison.
For this purpose, I have mocked(I don’t control the behaviour of this function) the gen_nano_id() .
Now, the problem that I am facing is mocking results in creation of always the same ids no matter what and I go in an infinite loop.
I am not able to figure out a way to reach the exit condition(nil) part of case comparison with this mocking approach of gen_nano_id .
