Add app details and icon cache (T-204)

app-modern/ui/gio/shell_test.go

@@ -79,6 +79,38 @@ func TestAppShellKeepsRowControlsByAppID(t *testing.T) {
 	}
 }
 
+func TestAppShellRendersSelectedDetailAndAppliedIcon(t *testing.T) {
+	item := application.CatalogListItem{
+		ID:          "json-parser",
+		Name:        "JSON解析工具",
+		Description: "格式化并检查 JSON",
+		Version:     "1.2.0",
+		Category:    "开发工具",
+		Tags:        []string{"JSON", "格式化"},
+		Homepage:    "https://example.invalid/json-parser",
+		Tutorial:    "https://example.invalid/json-parser/tutorial",
+		Status:      domain.StatusInstalled,
+		Installed:   true,
+	}
+	shell := NewAppShell("Modern", item)
+	icon := image.NewNRGBA(image.Rect(0, 0, 32, 32))
+	shell.ApplyIcon(item.ID, icon)
+	shell.model.Select(item.ID)
+
+	shell.Layout(testContext(image.Pt(1280, 800)), NewTheme())
+	if !shell.detailRendered {
+		t.Fatal("selected app detail was not rendered")
+	}
+	if _, exists := shell.icons[item.ID]; !exists {
+		t.Fatal("ApplyIcon did not retain the prepared image operation")
+	}
+
+	shell.ApplyIcon(item.ID, nil)
+	if _, exists := shell.icons[item.ID]; exists {
+		t.Fatal("ApplyIcon(nil) did not remove the image")
+	}
+}
+
 func testContext(size image.Point) layout.Context {
 	var operations op.Ops
 	return layout.Context{