Testing - Migrate QA DRAW tests to GTest (#823)

- Deletion of 20 legacy DRAW test files (.tcl format) from tests/bugs/ directories
- Addition of 15 new GTest C++ test files across multiple modules
- Removal of corresponding QA command implementations from TKQADraw

src/ModelingAlgorithms/TKExpress/GTests/Expr_GeneralExpression_Test.cxx

@@ -0,0 +1,54 @@
+// Copyright (c) 2025 OPEN CASCADE SAS
+//
+// This file is part of Open CASCADE Technology software library.
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License version 2.1 as published
+// by the Free Software Foundation, with special exception defined in the file
+// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
+// distribution for complete text of the license and disclaimer of any warranty.
+//
+// Alternatively, this file may be used under the terms of Open CASCADE
+// commercial license or contractual agreement.
+
+#include <Expr_GeneralExpression.hxx>
+#include <Expr_NamedUnknown.hxx>
+#include <ExprIntrp_GenExp.hxx>
+#include <TCollection_AsciiString.hxx>
+
+#include <gtest/gtest.h>
+
+TEST(Expr_GeneralExpression_Test, OCC902_ExpressionDerivative)
+{
+  // Bug OCC902: Bad derivative computation
+  // This test verifies that the derivative of Exp(5*x) is correctly computed
+  // The expected result is either "Exp(5*x)*5" or "5*Exp(5*x)"
+
+  TCollection_AsciiString anExpStr("5");
+  anExpStr.AssignCat("*x");
+  anExpStr.Prepend("Exp(");
+  anExpStr.AssignCat(")");
+
+  Handle(ExprIntrp_GenExp) anExprIntrp = ExprIntrp_GenExp::Create();
+
+  // Create the expression
+  anExprIntrp->Process(anExpStr);
+
+  ASSERT_TRUE(anExprIntrp->IsDone()) << "Expression interpretation should succeed";
+
+  Handle(Expr_GeneralExpression) anExpr = anExprIntrp->Expression();
+  ASSERT_FALSE(anExpr.IsNull()) << "Expression should not be null";
+
+  Handle(Expr_NamedUnknown)      aVar     = new Expr_NamedUnknown("x");
+  Handle(Expr_GeneralExpression) aNewExpr = anExpr->Derivative(aVar);
+
+  ASSERT_FALSE(aNewExpr.IsNull()) << "Derivative should not be null";
+
+  TCollection_AsciiString aDerivativeStr = aNewExpr->String();
+
+  // The derivative of Exp(5*x) should be either "Exp(5*x)*5" or "5*Exp(5*x)"
+  bool isCorrect = (aDerivativeStr == "Exp(5*x)*5") || (aDerivativeStr == "5*Exp(5*x)");
+
+  EXPECT_TRUE(isCorrect) << "Derivative result was: " << aDerivativeStr.ToCString()
+                         << ", expected either 'Exp(5*x)*5' or '5*Exp(5*x)'";
+}

src/ModelingAlgorithms/TKExpress/GTests/FILES.cmake

@@ -2,4 +2,5 @@
 set(OCCT_TKExpress_GTests_FILES_LOCATION "${CMAKE_CURRENT_LIST_DIR}")
 
 set(OCCT_TKExpress_GTests_FILES
+  Expr_GeneralExpression_Test.cxx
 )