[Sketcher] [gtest] Add SketchObject test

Create a document and then add a `SketchObject` to it. Does not work without
creating document.

Also `FCConfig.h` is needed for `FC_OS_WIN32`.

tests/src/Mod/Sketcher/App/SketchObject.cpp

@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#include "gtest/gtest.h"
+
+#include <FCConfig.h>
+
+#include <App/Application.h>
+#include <App/Document.h>
+#include <Mod/Sketcher/App/SketchObject.h>
+
+class SketchObjectTest: public ::testing::Test
+{
+protected:
+    static void SetUpTestSuite()
+    {
+        if (App::Application::GetARGC() == 0) {
+            int argc = 1;
+            char* argv[] = {"FreeCAD"};
+            App::Application::Config()["ExeName"] = "FreeCAD";
+            App::Application::init(argc, argv);
+        }
+    }
+
+    void SetUp() override
+    {
+        _docName = App::GetApplication().getUniqueDocumentName("test");
+        auto _doc = App::GetApplication().newDocument(_docName.c_str(), "testUser");
+        // TODO: Do we add a body first, or is just adding sketch sufficient for this test?
+        _sketchobj = static_cast<Sketcher::SketchObject*>(_doc->addObject("Sketcher::SketchObject"));
+    }
+
+    void TearDown() override
+    {
+        App::GetApplication().closeDocument(_docName.c_str());
+    }
+
+private:
+    // TODO: use shared_ptr or something else here?
+    Sketcher::SketchObject* _sketchobj;
+    std::string _docName;
+};
+
+TEST_F(SketchObjectTest, createSketchObject) // NOLINT
+{
+    // Arrange
+
+    // Act
+
+    // Assert
+}