fix: prevent double-skip in revalidate path by clearing fillRange context

server/middleware/caching/caching_revalidate.go

@@ -195,6 +195,9 @@ func (r *RevalidateProcessor) revalidate(c *Caching, resp *http.Response, req *h
 			return nil, xhttp.NewBizError(http.StatusRequestedRangeNotSatisfiable, nil)
 		}
 		c.log.Debugf("freshness cache by RawRange bytes=%d-%d", rng.Start, rng.End)
+		// lazilyRespond already applies correct range trimming; clear fillRange context
+		// to prevent fillRange.PostRequest from double-skipping the response body.
+		*req = *req.WithContext(context.WithValue(req.Context(), fillRangeKey{}, nil))
 		return c.lazilyRespond(req, rng.Start, rng.End)
 	}
 

tests/all-features/caching/revalidate_doube_skip_test.go

@@ -0,0 +1,100 @@
+package caching
+
+import (
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/omalloc/tavern/pkg/e2e"
+	xhttp "github.com/omalloc/tavern/pkg/x/http"
+)
+
+// RevalidateDoubleSkip 测试在 Revalidate 过程中，对已缓存的文件再次发起请求，上游相应 304 Not Modified，内部因为 fillRange 补块导致文件偏移错误
+//
+//	@see https://github.com/omalloc/tavern/issues/58
+func TestRevalidateDoubleSkip(t *testing.T) {
+	f := e2e.GenFile(t, 5<<20)
+
+	t.Run("test Revalidate normal old-file", func(t *testing.T) {
+		case1 := e2e.New("http://sendya.me.gslb.com/cases/revalidate-skip/file1.apk", e2e.RespCallbackFile(f, func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("X-Case", "old-file")
+			w.Header().Set("Cache-Control", "max-age=1") // 1s 过滤
+		}))
+		defer case1.Close()
+
+		resp, err := case1.Do(func(r *http.Request) {
+		})
+
+		t.Logf("resp size=%d", resp.ContentLength)
+		t.Logf("file path=%s", f.Path)
+
+		hashBody := e2e.HashBody(resp)
+		hashFile := e2e.HashFile(f.Path, 0, f.Size)
+
+		assert.NoError(t, err, "response should not error")
+
+		assert.Equal(t, http.StatusOK, resp.StatusCode, "response should be code 200")
+
+		assert.Equal(t, "old-file", resp.Header.Get("X-Case"), "response should be X-Case old-file")
+
+		assert.Equal(t, f.MD5, resp.Header.Get("ETag"), "response should be ETag")
+
+		assert.Equal(t, hashBody, hashFile, "response body should be equal to file MD5")
+	})
+
+	t.Run("test Revalidate skip old-file", func(t *testing.T) {
+		time.Sleep(1 * time.Second) // 等待上一个 case 的 max-age 过期
+
+		case1 := e2e.New("http://sendya.me.gslb.com/cases/revalidate-skip/file1.apk", e2e.RespCallback(func(w http.ResponseWriter, r *http.Request) {
+			for k, v := range r.Header {
+				t.Logf("header key=%s, value=%s", k, v)
+			}
+			since := r.Header.Get("If-None-Match")
+			t.Logf("If-None-Match=%s", since)
+
+			if since != f.MD5 {
+				w.Header().Set("X-Case", "old-file")
+				w.WriteHeader(http.StatusInternalServerError)
+				return
+			}
+
+			w.WriteHeader(http.StatusNotModified)
+			w.Header().Set("X-Case", "old-file")
+			w.Header().Set("Cache-Control", "max-age=1") // 1s 过滤
+		}))
+		defer case1.Close()
+
+		rr := xhttp.NewRequestRange(4341324, 4417533)
+
+		resp, err := case1.Do(func(r *http.Request) {
+			r.Header.Set("Range", rr.String())
+			t.Logf("New Request Range=%s", rr.String())
+		})
+
+		t.Logf("resp size=%d", resp.ContentLength)
+		t.Logf("file offset=%d, end=%d", rr.Start, rr.End)
+		t.Logf("file path=%s", f.Path)
+
+		hashBody := e2e.HashBody(resp)
+		hashFile := e2e.HashFile(f.Path, int(rr.Start), int(rr.End-rr.Start+1))
+
+		assert.NoError(t, err, "response should not error")
+
+		assert.Equal(t, http.StatusPartialContent, resp.StatusCode, "response should be code 206")
+
+		assert.Equal(t, rr.ContentRange(uint64(f.Size)), resp.Header.Get("Content-Range"), "response should be Content-Range")
+
+		assert.Equal(t, "old-file", resp.Header.Get("X-Case"), "response should be X-Case old-file")
+
+		assert.Equal(t, f.MD5, resp.Header.Get("ETag"), "response should be ETag")
+
+		assert.Equal(t, hashBody, hashFile, "response body should be equal to file MD5")
+	})
+
+	t.Run("PURGE", func(t *testing.T) {
+		e2e.Purge(t, "http://sendya.me.gslb.com/cases/revalidate-skip/file1.apk")
+	})
+
+}

tests/all-features/caching/revalidate_test.go

@@ -5,9 +5,10 @@ import (
 	"testing"
 	"time"
 
+	"github.com/stretchr/testify/assert"
+
 	"github.com/omalloc/tavern/pkg/e2e"
 	xhttp "github.com/omalloc/tavern/pkg/x/http"
-	"github.com/stretchr/testify/assert"
 )
 
 func TestRevalidateDiscard(t *testing.T) {
@@ -82,7 +83,7 @@ func TestRevalidateDiscard(t *testing.T) {
 		assert.Equal(t, hashBody, hashFile, "response body should be equal to file MD5")
 	})
 
-	// t.Run("PURGE", func(t *testing.T) {
-	// 	e2e.Purge(t, "http://sendya.me.gslb.com/cases/revalidate/file1.apk")
-	// })
+	t.Run("PURGE", func(t *testing.T) {
+		e2e.Purge(t, "http://sendya.me.gslb.com/cases/revalidate/file1.apk")
+	})
 }