File/package naming convention conforming better to go standards - as ugly as it is

internal/mock/findatender/ratelimit_test.go

@@ -0,0 +1,134 @@
+package mock
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestRateLimitWindows(t *testing.T) {
+	now := time.Date(2026, 10, 6, 10, 3, 20, 0, time.UTC) // first request of the hour
+	rl := NewRateLimiter(12, 5*time.Minute)
+	rl.now = func() time.Time { return now }
+
+	for i := 0; i < 12; i++ {
+		if ok, _ := rl.allow("a"); !ok {
+			t.Fatalf("request %d rejected", i+1)
+		}
+	}
+	now = now.Add(100 * time.Second) // 10:05:00, window ends 10:08:20
+	if ok, secs := rl.allow("a"); ok || secs != 200 {
+		t.Fatalf("want reject with 200s, got ok=%v secs=%d", ok, secs)
+	}
+	if ok, _ := rl.allow("b"); !ok {
+		t.Fatal("other client should be unaffected")
+	}
+	now = time.Date(2026, 10, 6, 10, 8, 20, 0, time.UTC) // next window opens
+	if ok, _ := rl.allow("a"); !ok {
+		t.Fatal("new window should allow")
+	}
+
+	// Window 10:58:20-11:03:20 is cut short by the new hour at 11:00:00.
+	now = time.Date(2026, 10, 6, 10, 58, 30, 0, time.UTC)
+	for i := 0; i < 12; i++ {
+		rl.allow("a")
+	}
+	if ok, secs := rl.allow("a"); ok || secs != 90 {
+		t.Fatalf("want reject with 90s, got ok=%v secs=%d", ok, secs)
+	}
+	now = time.Date(2026, 10, 6, 11, 0, 5, 0, time.UTC) // re-anchors here
+	if ok, _ := rl.allow("a"); !ok {
+		t.Fatal("new hour should allow")
+	}
+}
+
+func TestClientKey(t *testing.T) {
+	cases := map[string]string{
+		"192.0.2.1:1234": "192.0.2.1",
+		"[::1]:8080":     "::1",
+		"no-port":        "no-port", // not host:port, used as-is
+	}
+	for addr, want := range cases {
+		req := httptest.NewRequest("GET", "/", nil)
+		req.RemoteAddr = addr
+		if got := clientKey(req); got != want {
+			t.Errorf("clientKey(%q) = %q, want %q", addr, got, want)
+		}
+	}
+}
+
+func TestRateLimitMiddleware(t *testing.T) {
+	now := time.Date(2026, 10, 6, 10, 0, 0, 0, time.UTC)
+	rl := NewRateLimiter(2, 5*time.Minute)
+	rl.now = func() time.Time { return now }
+
+	calls := 0
+	h := rl.Middleware(func(w http.ResponseWriter, req *http.Request) {
+		calls++
+		w.WriteHeader(http.StatusOK)
+	})
+	do := func(addr string) *httptest.ResponseRecorder {
+		req := httptest.NewRequest("GET", "/", nil)
+		req.RemoteAddr = addr
+		rec := httptest.NewRecorder()
+		h(rec, req)
+		return rec
+	}
+
+	for i := 0; i < 2; i++ {
+		if rec := do("192.0.2.1:1000"); rec.Code != http.StatusOK {
+			t.Fatalf("request %d: status %d", i+1, rec.Code)
+		}
+	}
+	// Same host, different port: still the same client.
+	rec := do("192.0.2.1:2000")
+	if rec.Code != http.StatusTooManyRequests {
+		t.Fatalf("status %d, want 429", rec.Code)
+	}
+	if got := rec.Header().Get("Retry-After"); got != "300" {
+		t.Errorf("Retry-After = %q, want 300", got)
+	}
+	if !strings.Contains(rec.Body.String(), "Rate limit of 2 exceeded") ||
+		!strings.Contains(rec.Body.String(), "300 seconds") {
+		t.Errorf("body = %q", rec.Body.String())
+	}
+	if calls != 2 {
+		t.Errorf("next called %d times, want 2", calls)
+	}
+	if rec := do("192.0.2.2:1000"); rec.Code != http.StatusOK {
+		t.Errorf("other client: status %d", rec.Code)
+	}
+}
+
+// Once more than 10000 clients are tracked, a new client in a new hour drops
+// every client left over from earlier hours.
+func TestRateLimitPrunesStaleClients(t *testing.T) {
+	now := time.Date(2026, 10, 6, 10, 30, 0, 0, time.UTC)
+	rl := NewRateLimiter(1, time.Minute)
+	rl.now = func() time.Time { return now }
+
+	for i := 0; i <= 10000; i++ {
+		rl.allow(strconv.Itoa(i))
+	}
+	if len(rl.clients) != 10001 {
+		t.Fatalf("tracking %d clients", len(rl.clients))
+	}
+
+	// Same hour: nothing is stale, so nothing is dropped.
+	rl.allow("same-hour")
+	if len(rl.clients) != 10002 {
+		t.Fatalf("same hour: tracking %d clients, want 10002", len(rl.clients))
+	}
+
+	now = now.Add(time.Hour)
+	rl.allow("new")
+	if len(rl.clients) != 1 {
+		t.Fatalf("after prune: tracking %d clients, want 1", len(rl.clients))
+	}
+	if _, ok := rl.clients["new"]; !ok {
+		t.Fatal("new client was pruned")
+	}
+}