tests: add http policy integration tests

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/github.com/moby/buildkit/util/testutil/httpserver/server.go

@@ -0,0 +1,113 @@
+package httpserver
+
+import (
+	"bytes"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"slices"
+	"sync"
+	"time"
+)
+
+type TestServer struct {
+	*httptest.Server
+	mu     sync.Mutex
+	routes map[string]*Response
+	stats  map[string]*Stat
+}
+
+func NewTestServer(routes map[string]*Response) *TestServer {
+	ts := &TestServer{
+		routes: routes,
+		stats:  map[string]*Stat{},
+	}
+	ts.Server = httptest.NewServer(ts)
+	return ts
+}
+
+func (s *TestServer) SetRoute(name string, resp *Response) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.routes[name] = resp
+}
+
+func (s *TestServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	s.mu.Lock()
+	resp, ok := s.routes[r.URL.Path]
+	if !ok {
+		w.WriteHeader(http.StatusNotFound)
+		s.mu.Unlock()
+		return
+	}
+
+	if _, ok := s.stats[r.URL.Path]; !ok {
+		s.stats[r.URL.Path] = &Stat{}
+	}
+
+	s.stats[r.URL.Path].AllRequests++
+	s.stats[r.URL.Path].Requests = append(s.stats[r.URL.Path].Requests, newRequest(r))
+
+	if resp.LastModified != nil {
+		w.Header().Set("Last-Modified", resp.LastModified.Format(time.RFC850))
+	}
+
+	if resp.ContentEncoding != "" {
+		w.Header().Set("Content-Encoding", resp.ContentEncoding)
+	}
+
+	if resp.ContentDisposition != "" {
+		w.Header().Set("Content-Disposition", resp.ContentDisposition)
+	}
+
+	if resp.Etag != "" {
+		w.Header().Set("ETag", resp.Etag)
+		if match := r.Header.Get("If-None-Match"); match == resp.Etag {
+			w.WriteHeader(http.StatusNotModified)
+			s.stats[r.URL.Path].CachedRequests++
+			s.mu.Unlock()
+			return
+		}
+	}
+
+	s.mu.Unlock()
+
+	w.WriteHeader(http.StatusOK)
+	io.Copy(w, bytes.NewReader(resp.Content))
+}
+
+func (s *TestServer) Stats(name string) (st Stat) {
+	if st, ok := s.stats[name]; ok {
+		return *st
+	}
+	return
+}
+
+type Response struct {
+	Content            []byte
+	Etag               string
+	LastModified       *time.Time
+	ContentEncoding    string
+	ContentDisposition string
+}
+
+type Stat struct {
+	AllRequests, CachedRequests int
+	Requests                    []Request
+}
+
+type Request struct {
+	Method string
+	Header http.Header
+}
+
+func newRequest(r *http.Request) Request {
+	headers := http.Header{}
+	for k, v := range r.Header {
+		headers[k] = slices.Clone(v)
+	}
+	return Request{
+		Method: r.Method,
+		Header: headers,
+	}
+}