feat(canvas): 条件读取与历史 - 减少画布同步传输并校准版本

backend/internal/handler/user_data_page_test.go

@@ -1,8 +1,16 @@
 package handler
 
 import (
+	"bytes"
+	"compress/gzip"
+	"encoding/json"
+	"io"
+	"net/http/httptest"
+	"strings"
 	"testing"
+	"time"
 
+	"infinite-canvas/backend/internal/model"
 	"infinite-canvas/backend/internal/service"
 
 	"github.com/gin-gonic/gin"
@@ -30,3 +38,64 @@ func TestUserDataIncrementalRoutesAreRegistered(t *testing.T) {
 		}
 	}
 }
+
+func TestCanvasProjectResponseETagChangesWithRevisionMetadata(t *testing.T) {
+	project := &model.CanvasProject{Revision: 7, UpdatedAt: time.Date(2026, 9, 28, 12, 0, 0, 123000000, time.UTC)}
+	first := canvasProjectResponseETag(project)
+	if first != `W/"canvas-7"` {
+		t.Fatalf("unexpected canvas ETag: %s", first)
+	}
+	if !ifNoneMatch(`"canvas-7"`, first) || !ifNoneMatch(first, first) {
+		t.Fatal("strong and weak validators should match for conditional GET")
+	}
+	project.Revision++
+	if first == canvasProjectResponseETag(project) {
+		t.Fatal("revision change must invalidate the canvas ETag")
+	}
+}
+
+func TestAcceptsGzipHonorsQualityAndWildcard(t *testing.T) {
+	for _, test := range []struct {
+		header string
+		want   bool
+	}{
+		{header: "gzip, br", want: true},
+		{header: "gzip;q=0, *;q=1", want: false},
+		{header: "br, *;q=0.5", want: true},
+		{header: "br, gzip;q=0.2", want: true},
+		{header: "br, gzip;q=0", want: false},
+	} {
+		if got := acceptsGzip(test.header); got != test.want {
+			t.Errorf("acceptsGzip(%q) = %v, want %v", test.header, got, test.want)
+		}
+	}
+}
+
+func TestOkCanvasProjectCompressesLargeResponses(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	recorder := httptest.NewRecorder()
+	ctx, _ := gin.CreateTestContext(recorder)
+	ctx.Request = httptest.NewRequest("GET", "/api/canvas-projects/canvas", nil)
+	ctx.Request.Header.Set("Accept-Encoding", "gzip")
+	project := json.RawMessage(`{"nodes":["` + strings.Repeat("x", 2048) + `"]}`)
+
+	okCanvasProject(ctx, project)
+
+	if got := recorder.Header().Get("Content-Encoding"); got != "gzip" {
+		t.Fatalf("Content-Encoding = %q, want gzip", got)
+	}
+	reader, err := gzip.NewReader(bytes.NewReader(recorder.Body.Bytes()))
+	if err != nil {
+		t.Fatal(err)
+	}
+	body, err := io.ReadAll(reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := reader.Close(); err != nil {
+		t.Fatal(err)
+	}
+	if !json.Valid(body) {
+		t.Fatalf("decompressed response is not valid JSON: %s", body)
+	}
+}