diff --git a/src/ai/api/ai_testmode.cpp b/src/ai/api/ai_testmode.cpp
new file mode 100644
--- /dev/null
+++ b/src/ai/api/ai_testmode.cpp
@@ -0,0 +1,26 @@
+/* $Id$ */
+
+/** @file ai_testmode.cpp Implementation of AITestMode. */
+
+#include "ai_testmode.hpp"
+#include "../../command_type.h"
+
+bool AITestMode::ModeProc(TileIndex tile, uint32 p1, uint32 p2, uint procc, CommandCost costs)
+{
+	/* In test mode we only return 'false', telling the DoCommand it
+		*  should stop after testing the command and return with that result. */
+	return false;
+}
+
+AITestMode::AITestMode()
+{
+	this->last_mode     = this->GetDoCommandMode();
+	this->last_instance = this->GetDoCommandModeInstance();
+	this->SetDoCommandMode(&AITestMode::ModeProc, this);
+}
+
+AITestMode::~AITestMode()
+{
+	assert(this->GetDoCommandModeInstance() == this);
+	this->SetDoCommandMode(this->last_mode, this->last_instance);
+}