imgui-test: Added IMGUI_TEST_ENGINE_LOG macro to emit into test log from core or user land.

imgui_internal.h

@@ -1660,11 +1660,14 @@ extern void                 ImGuiTestEngineHook_PreNewFrame(ImGuiContext* ctx);
 extern void                 ImGuiTestEngineHook_PostNewFrame(ImGuiContext* ctx);
 extern void                 ImGuiTestEngineHook_ItemAdd(ImGuiContext* ctx, const ImRect& bb, ImGuiID id);
 extern void                 ImGuiTestEngineHook_ItemInfo(ImGuiContext* ctx, ImGuiID id, const char* label, ImGuiItemStatusFlags flags);
-#define IMGUI_TEST_ENGINE_ITEM_ADD(_BB, _ID)                ImGuiTestEngineHook_ItemAdd(&g, _BB, _ID)               // Register status flags
-#define IMGUI_TEST_ENGINE_ITEM_INFO(_ID, _LABEL, _FLAGS)    ImGuiTestEngineHook_ItemInfo(&g, _ID, _LABEL, _FLAGS)   // Register status flags
+extern void                 ImGuiTestEngineHook_Log(ImGuiContext* ctx, const char* fmt, ...);
+#define IMGUI_TEST_ENGINE_ITEM_ADD(_BB, _ID)                ImGuiTestEngineHook_ItemAdd(&g, _BB, _ID)               // Register item bounding box
+#define IMGUI_TEST_ENGINE_ITEM_INFO(_ID, _LABEL, _FLAGS)    ImGuiTestEngineHook_ItemInfo(&g, _ID, _LABEL, _FLAGS)   // Register item label and status flags (optional)
+#define IMGUI_TEST_ENGINE_LOG(_FMT, ...)                    ImGuiTestEngineHook_Log(&g, _FMT, __VA_ARGS__)          // Custom log entry from user land into test log
 #else
 #define IMGUI_TEST_ENGINE_ITEM_ADD(_BB, _ID)                do { } while (0)
 #define IMGUI_TEST_ENGINE_ITEM_INFO(_ID, _LABEL, _FLAGS)    do { } while (0)
+#define IMGUI_TEST_ENGINE_LOG(_FMT, ...)                    do { } while (0)
 #endif
 
 #if defined(__clang__)