Add ability to seed the KIID generator

Fixes https://gitlab.com/kicad/code/kicad/-/issues/9689

common/kiid.cpp

@@ -37,7 +37,8 @@
 
 
 // Create only once, as seeding is *very* expensive
-static boost::uuids::random_generator randomGenerator;
+static boost::mt19937 rng;
+static boost::uuids::basic_random_generator<boost::mt19937> randomGenerator( &rng );
 
 // These don't have the same performance penalty, but might as well be consistent
 static boost::uuids::string_generator stringGenerator;
@@ -243,6 +244,12 @@ void KIID::CreateNilUuids( bool aNil )
 }
 
 
+void KIID::SeedGenerator( unsigned int aSeed )
+{
+    rng.seed( aSeed );
+}
+
+
 KIID_PATH::KIID_PATH( const wxString& aString )
 {
     for( const wxString& pathStep : wxSplit( aString, '/' ) )

include/kiid.h

@@ -63,6 +63,17 @@ public:
 
     static void CreateNilUuids( bool aNil = true );
 
+    /**
+     * Re-initialize the UUID generator with a given seed (for testing or QA purposes)
+     *
+     * WARNING: Do not call this function from within KiCad or via a Python action plugin.  It is
+     * only to be used inside QA tests or in external Python scripts.  Resetting the UUID generator
+     * in the middle of a KiCad GUI run will potentially have harmful effects on file integrity.
+     *
+     * @param aSeed is a seed to pass to the boost::mt19937 pseudo-random number generator
+     */
+    static void SeedGenerator( unsigned int aSeed );
+
     /**
      * Change an existing time stamp based UUID into a true UUID.
      *

qa/common/CMakeLists.txt

@@ -37,6 +37,7 @@ set( common_srcs
     test_eda_rect.cpp
     test_lib_table.cpp
     test_kicad_string.cpp
+    test_kiid.cpp
     test_property.cpp
     test_refdes_utils.cpp
     test_title_block.cpp

qa/common/test_kiid.cpp

@@ -0,0 +1,45 @@
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 1992-2021 KiCad Developers, see AUTHORS.txt for contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <boost/test/unit_test.hpp>
+#include <kiid.h>
+
+
+BOOST_AUTO_TEST_SUITE( Kiid )
+
+
+BOOST_AUTO_TEST_CASE( Seeding )
+{
+    KIID::SeedGenerator( 0l );
+
+    KIID a;
+    BOOST_CHECK_EQUAL( a.Hash(), 15552532309556242017ul );
+
+    KIID b;
+    BOOST_CHECK_EQUAL( b.Hash(), 13842873335846156666ul );
+
+    KIID c;
+    BOOST_CHECK_EQUAL( c.Hash(), 15995408467689523943ul );
+
+    KIID d;
+    BOOST_CHECK_EQUAL( d.Hash(), 4943106325342180035ul );
+}
+
+
+BOOST_AUTO_TEST_SUITE_END()