at-container-registry/pkg/billing/tier_resolution_test.go

//go:build billing

package billing

import (
	"testing"

	"github.com/stripe/stripe-go/v84"
)

// Tier resolution used to key on the price ID alone, which quietly inverted
// what a price change is supposed to do. Stripe prices are immutable, so
// raising a price means creating a new one, and Stripe never moves existing
// subscribers off the old one. Matching on price therefore dropped exactly the
// subscribers a price change is meant to leave untouched — and dropped them
// into the silent branch, where the event is answered 200, recorded as
// processed, and can never be redelivered.

func productPrice(priceID, productID string) *stripe.Price {
	p := &stripe.Price{ID: priceID}
	if productID != "" {
		p.Product = &stripe.Product{ID: productID}
	}
	return p
}

func tierTestConfig() *Config {
	return &Config{Tiers: []BillingTierConfig{
		{Name: "free"},
		{
			Name:               "supporter",
			StripeProduct:      "prod_supporter",
			StripePriceMonthly: "price_supporter_v2",
		},
		{
			Name:               "pro",
			StripePriceMonthly: "price_pro_only",
		},
	}}
}

// TestResolveTier_GrandfatheredPriceResolvesByProduct is the whole point of
// keying on the product: a subscriber still billing on price_supporter_v1,
// which no longer appears anywhere in the config, keeps their tier.
func TestResolveTier_GrandfatheredPriceResolvesByProduct(t *testing.T) {
	m := &Manager{cfg: tierTestConfig()}

	name, rank := m.resolveTier(productPrice("price_supporter_v1_retired", "prod_supporter"))
	if name != "supporter" || rank != 1 {
		t.Errorf("resolveTier(retired price, live product) = (%q, %d), want (\"supporter\", 1) — "+
			"a subscriber on the old price lost their tier", name, rank)
	}
}

// TestResolveTier_FallsBackToPriceWhenNoProductConfigured: a config written
// before stripe_product existed must keep resolving exactly as it did.
func TestResolveTier_FallsBackToPriceWhenNoProductConfigured(t *testing.T) {
	m := &Manager{cfg: tierTestConfig()}

	name, rank := m.resolveTier(productPrice("price_pro_only", "prod_pro_unconfigured"))
	if name != "pro" || rank != 2 {
		t.Errorf("resolveTier = (%q, %d), want (\"pro\", 2) — the price fallback stopped working", name, rank)
	}
}

// TestResolveTier_ProductWinsOverPrice: when both could match, the product
// decides. Otherwise a price ID left behind on the wrong tier could outvote the
// product and grant the wrong entitlement.
func TestResolveTier_ProductWinsOverPrice(t *testing.T) {
	m := &Manager{cfg: &Config{Tiers: []BillingTierConfig{
		{Name: "free"},
		{Name: "supporter", StripeProduct: "prod_supporter"},
		{Name: "pro", StripePriceMonthly: "price_shared"},
	}}}

	name, _ := m.resolveTier(productPrice("price_shared", "prod_supporter"))
	if name != "supporter" {
		t.Errorf("resolveTier = %q, want \"supporter\" — the price ID outvoted the product", name)
	}
}

// TestResolveTier_UnknownEverythingIsUnresolved keeps the negative honest: a
// price on a product the config has never heard of must not resolve to a tier.
func TestResolveTier_UnknownEverythingIsUnresolved(t *testing.T) {
	m := &Manager{cfg: tierTestConfig()}

	if name, rank := m.resolveTier(productPrice("price_unknown", "prod_unknown")); name != "" || rank != -1 {
		t.Errorf("resolveTier(unknown) = (%q, %d), want (\"\", -1)", name, rank)
	}
	if name, rank := m.resolveTier(nil); name != "" || rank != -1 {
		t.Errorf("resolveTier(nil) = (%q, %d), want (\"\", -1)", name, rank)
	}
}