Improve readability and fully comply with RFC7232

middleware/fileserver.go

@@ -130,8 +130,8 @@ func (fh *fileHandler) serveFile(w http.ResponseWriter, r *http.Request, name st
 	}
 
 	// Add ETag header
-	e := fmt.Sprintf("\"%x-%x\"", d.ModTime().Unix(), d.Size())
-	w.Header().Set("Etag", e)
+	e := fmt.Sprintf(`W/"%x-%x"`, d.ModTime().Unix(), d.Size())
+	w.Header().Set("ETag", e)
 
 	// Note: Errors generated by ServeContent are written immediately
 	// to the response. This usually only happens if seeking fails (rare).

middleware/fileserver_test.go

@@ -62,14 +62,14 @@ func TestServeHTTP(t *testing.T) {
 			url:                 "https://foo/file1.html",
 			expectedStatus:      http.StatusOK,
 			expectedBodyContent: testFiles["file1.html"],
-			expectedEtag:        "\"1e240-13\"",
+			expectedEtag:        `W/"1e240-13"`,
 		},
 		// Test 3 - access folder with index file with trailing slash
 		{
 			url:                 "https://foo/dirwithindex/",
 			expectedStatus:      http.StatusOK,
 			expectedBodyContent: testFiles[filepath.Join("dirwithindex", "index.html")],
-			expectedEtag:        "\"1e240-20\"",
+			expectedEtag:        `W/"1e240-20"`,
 		},
 		// Test 4 - access folder with index file without trailing slash
 		{
@@ -109,7 +109,7 @@ func TestServeHTTP(t *testing.T) {
 			url:                 "https://foo/dirwithindex/index.html",
 			expectedStatus:      http.StatusOK,
 			expectedBodyContent: testFiles[filepath.Join("dirwithindex", "index.html")],
-			expectedEtag:        "\"1e240-20\"",
+			expectedEtag:        `W/"1e240-20"`,
 		},
 		// Test 11 - send a request with query params
 		{