"paddle_create_customer() returns error when email is already used"
"Paddle API error: customer email conflicts with customer of id ctm_01jwp3yens988zjex66a8hh7rz"
"paddle_create_customer() returns error when email is not filled"
"`email` is required and must be a non-empty string."
"paddle_update_customer() returns error with wrong status"
"paddle_update_customer() returns error with wrond customer id"
"paddle_generate_auth_token() fails with invalid ID"
"paddle_list_customer() returns error with wrong inputs1"
"`status` must be one of: active, archived"
"paddle_list_customer() returns error with wrong inputs3"
"`search` must be one of: id, name, email"
"paddle_list_customer() returns error with wrong inputs4"
"`country_code` must be a valid 2-letter"
"`address_id` must be a non-empty string"
"Each contact must be a list containing at least an `email` field"
"Each contact must contain a valid email address"
"`business_id` must be a non-empty string"
"Each contact must include a valid `email` field"

test_that("paddle_list_discounts() validates inputs correctly", {
"`mode` must be one of: standard, custom")
test_that("paddle_create_discount() validates required and conditional fields", {
expect_error(paddle_create_discount(description = "New Discount", type = "percentage"),
"`amount`, `description`, and `type` are required")
expect_error(paddle_create_discount(amount = "10", description = "New Discount", type = "flat", currency_code = "USD", mode = "invalid"),
expect_error(paddle_create_discount(amount = "10", description = "New Discount", type = "invalid"),
expect_error(paddle_create_discount(amount = "10", description = "Flat Discount", type = "flat"),
expect_error(paddle_create_discount(amount = "10", description = "New Discount", type = "percentage", code = "%%INVALID%%"),
test_that("paddle_update_discount() validates inputs correctly", {
expect_error(paddle_update_discount(id = "dsc_01jwxsz8xrf3j3g32nrx3eycn9", type = "invalid"),
expect_error(paddle_update_discount(id = "dsc_01jwxsz8xrf3j3g32nrx3eycn9", status = "invalid"),
expect_error(paddle_update_discount(id = "dsc_01jwxsz8xrf3j3g32nrx3eycn9", mode = "invalid"),
expect_error(paddle_update_discount(id = "dsc_01jwxsz8xrf3j3g32nrx3eycn9", type = "flat"),
expect_error(paddle_update_discount(id = "dsc_01jwxsz8xrf3j3g32nrx3eycn9", code = "###BADCODE###"),