Clarify persisted cover handling

backend/cover_test.go

@@ -2,11 +2,15 @@ package main
 
 import (
 	"context"
+	"crypto/sha256"
 	"errors"
 	"net/http"
 	"net/http/httptest"
 	"sync/atomic"
 	"testing"
+
+	"bookmarkmanager/backend/internal/pgtest"
+	"bookmarkmanager/backend/internal/store"
 )
 
 // fakeCovers stands in for the headless browser. It counts calls so the test
@@ -95,6 +99,41 @@ func TestKaganeCoverServesStoredBytesWithoutBrowser(t *testing.T) {
 	}
 }
 
+func TestKaganeCoverServesPersistedBytesAfterRestart(t *testing.T) {
+	url := pgtest.URL(t)
+	owner := store.Owner{
+		DiscordID: "cover-owner",
+		TokenHash: sha256.Sum256([]byte("cover-owner-token")),
+	}
+	first, err := store.Open(url, owner)
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+	if err := first.PutKaganeCover(testCoverID, []byte("survives-restart"), "image/jpeg"); err != nil {
+		first.Close()
+		t.Fatalf("PutKaganeCover: %v", err)
+	}
+	if err := first.Close(); err != nil {
+		t.Fatalf("close first store: %v", err)
+	}
+
+	second, err := store.Open(url, owner)
+	if err != nil {
+		t.Fatalf("reopen: %v", err)
+	}
+	defer second.Close()
+	cf := &fakeCovers{err: errors.New("browser must not be called after restart")}
+	cfg := testConfig()
+	cfg.Covers = cf
+	rr := getCover(t, newRouter(second, cfg), "/img/kagane/"+testCoverID, sessionCookie(t, second))
+	if rr.Code != http.StatusOK || rr.Body.String() != "survives-restart" {
+		t.Fatalf("restarted request = (%d, %q), want (200, survives-restart)", rr.Code, rr.Body.String())
+	}
+	if got := cf.calls.Load(); got != 0 {
+		t.Fatalf("fetcher called %d times after restart, want 0", got)
+	}
+}
+
 // The proxy reaches a headless browser, so it is not open to the internet.
 func TestKaganeCoverRequiresSession(t *testing.T) {
 	cf := &fakeCovers{body: []byte("x"), contentType: "image/webp"}
@@ -147,9 +186,11 @@ func TestKaganeCoverRejectsBadInput(t *testing.T) {
 			if rr.Code != http.StatusNotFound {
 				t.Fatalf("status = %d, want 404", rr.Code)
 			}
-			if _, _, ok, err := st.GetKaganeCover(testCoverID); err != nil {
+			_, _, ok, err := st.GetKaganeCover(tc.id)
+			if err != nil {
 				t.Fatalf("GetKaganeCover after rejection: %v", err)
-			} else if ok {
+			}
+			if ok {
 				t.Fatal("rejected cover was persisted")
 			}
 		})