From 2a0c30f9532cd4316c6a051cea89b9356a165361 Mon Sep 17 00:00:00 2001
From: NotAShelf <raf@notashelf.dev>
Date: Fri, 6 Mar 2026 17:00:38 +0300
Subject: [PATCH] server: integration tests for route reuse and upstream
 fallback

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I0d476da19941238b32c6adf87dac2d876a6a6964
---
 internal/server/integration_test.go | 97 +++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 internal/server/integration_test.go

diff --git a/internal/server/integration_test.go b/internal/server/integration_test.go
new file mode 100644
index 0000000..b78e77a
--- /dev/null
+++ b/internal/server/integration_test.go
@@ -0,0 +1,97 @@
+package server_test
+
+import (
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"strings"
+	"testing"
+	"time"
+
+	"notashelf.dev/ncro/internal/cache"
+	"notashelf.dev/ncro/internal/config"
+	"notashelf.dev/ncro/internal/prober"
+	"notashelf.dev/ncro/internal/router"
+	"notashelf.dev/ncro/internal/server"
+)
+
+// Verifies that the second identical narinfo request uses the cached route.
+func TestRouteReuseOnSecondRequest(t *testing.T) {
+	requestCount := 0
+	upstream := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if strings.HasSuffix(r.URL.Path, ".narinfo") {
+			requestCount++
+			w.Header().Set("Content-Type", "text/x-nix-narinfo")
+			io.WriteString(w, "StorePath: /nix/store/test-pkg\nURL: nar/test.nar\n")
+			return
+		}
+		w.WriteHeader(404)
+	}))
+	defer upstream.Close()
+
+	f, _ := os.CreateTemp("", "ncro-int-*.db")
+	f.Close()
+	defer os.Remove(f.Name())
+	db, _ := cache.Open(f.Name(), 1000)
+	defer db.Close()
+
+	p := prober.New(0.3)
+	p.RecordLatency(upstream.URL, 10)
+	r := router.New(db, p, time.Hour, 5*time.Second)
+	ts := httptest.NewServer(server.New(r, p, []config.UpstreamConfig{{URL: upstream.URL}}))
+	defer ts.Close()
+
+	resp1, _ := http.Get(ts.URL + "/deadbeef00000000.narinfo")
+	io.Copy(io.Discard, resp1.Body)
+	resp1.Body.Close()
+
+	resp2, _ := http.Get(ts.URL + "/deadbeef00000000.narinfo")
+	io.Copy(io.Discard, resp2.Body)
+	resp2.Body.Close()
+
+	if resp1.StatusCode != 200 || resp2.StatusCode != 200 {
+		t.Errorf("expected 200/200, got %d/%d", resp1.StatusCode, resp2.StatusCode)
+	}
+}
+
+// Verifies that when the best-seeded upstream returns 404, the fallback upstream is used.
+func TestUpstreamFailoverFallback(t *testing.T) {
+	good := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/x-nix-narinfo")
+		io.WriteString(w, "StorePath: /nix/store/fallback-pkg\n")
+	}))
+	defer good.Close()
+
+	bad := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(404)
+	}))
+	defer bad.Close()
+
+	f, _ := os.CreateTemp("", "ncro-fb-*.db")
+	f.Close()
+	defer os.Remove(f.Name())
+	db, _ := cache.Open(f.Name(), 1000)
+	defer db.Close()
+
+	p := prober.New(0.3)
+	p.RecordLatency(bad.URL, 1)   // bad appears fastest
+	p.RecordLatency(good.URL, 50)
+
+	r := router.New(db, p, time.Hour, 5*time.Second)
+	ts := httptest.NewServer(server.New(r, p, []config.UpstreamConfig{
+		{URL: bad.URL},
+		{URL: good.URL},
+	}))
+	defer ts.Close()
+
+	resp, err := http.Get(ts.URL + "/cafebabe00000000.narinfo")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		t.Errorf("expected 200 via fallback, got %d", resp.StatusCode)
+	}
+}