test(chromium): cover header and footer image deduplication

test/integration/scenario/images_test.go

@@ -0,0 +1,106 @@
+package scenario
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+)
+
+func TestCheckImageXObjectReuse(t *testing.T) {
+	t.Parallel()
+
+	const header = `page   num  type   width height color comp bpc  enc interp  object ID x-ppi y-ppi size ratio
+--------------------------------------------------------------------------------------------
+`
+	imageRow := func(page, object, generation int) string {
+		return fmt.Sprintf("%d %d image 32 32 rgb 3 8 image no %d %d 96 96 3104B 101%%\n", page, page-1, object, generation)
+	}
+
+	tests := []struct {
+		name    string
+		output  string
+		pages   int
+		wantErr string
+	}{
+		{
+			name:   "one page baseline",
+			output: header + imageRow(1, 7, 0),
+			pages:  1,
+		},
+		{
+			name:   "three pages share one image object",
+			output: header + imageRow(1, 7, 0) + imageRow(2, 7, 0) + imageRow(3, 7, 0),
+			pages:  3,
+		},
+		{
+			name:    "regression embeds a different object per page",
+			output:  header + imageRow(1, 7, 0) + imageRow(2, 8, 0) + imageRow(3, 9, 0),
+			pages:   3,
+			wantErr: "expected 1 unique image XObject(s) shared across 3 page(s), but actual is 3",
+		},
+		{
+			name:    "object generation is part of its identity",
+			output:  header + imageRow(1, 7, 0) + imageRow(2, 7, 1) + imageRow(3, 7, 0),
+			pages:   3,
+			wantErr: "expected 1 unique image XObject(s) shared across 3 page(s), but actual is 2",
+		},
+		{
+			name:    "image missing from a page",
+			output:  header + imageRow(1, 7, 0) + imageRow(3, 7, 0),
+			pages:   3,
+			wantErr: "expected 1 image appearance(s) on page 2, but actual is 0",
+		},
+		{
+			name:    "no image cannot pass",
+			output:  header,
+			pages:   1,
+			wantErr: "expected 1 image appearance(s) on page 1, but actual is 0",
+		},
+		{
+			name:    "repeated image only on first page cannot pass",
+			output:  header + imageRow(1, 7, 0) + imageRow(1, 7, 0) + imageRow(1, 7, 0),
+			pages:   3,
+			wantErr: "expected 1 image appearance(s) on page 1, but actual is 3",
+		},
+		{
+			name:    "image on unexpected page",
+			output:  header + imageRow(1, 7, 0) + imageRow(2, 7, 0),
+			pages:   1,
+			wantErr: "image on page 2 outside expected range 1-1",
+		},
+		{
+			name:    "tool error cannot pass",
+			output:  "Syntax Error: Couldn't find trailer dictionary",
+			pages:   1,
+			wantErr: "invalid pdfimages -list output:",
+		},
+		{
+			name:    "malformed image row",
+			output:  header + "1 0 image\n",
+			pages:   1,
+			wantErr: "invalid pdfimages -list row:",
+		},
+		{
+			name:    "inline image has no reusable object ID",
+			output:  header + "1 0 image 32 32 rgb 3 8 image no [inline] - 96 96 3104B 101%\n",
+			pages:   1,
+			wantErr: "parse image object ID",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			err := checkImageXObjectReuse(tt.output, 1, tt.pages)
+			if tt.wantErr == "" {
+				if err != nil {
+					t.Fatalf("unexpected error: %v", err)
+				}
+				return
+			}
+			if err == nil || !strings.Contains(err.Error(), tt.wantErr) {
+				t.Fatalf("expected error containing %q, got %v", tt.wantErr, err)
+			}
+		})
+	}
+}