diff --git a/main.cxx b/src/ast.hxx
similarity index 73%
rename from main.cxx
rename to src/ast.hxx
index 3dc8e00..3684cd2 100644
--- a/main.cxx
+++ b/src/ast.hxx
@@ -1,6 +1,5 @@
 // Include necessary C++ standard library headers.
 #include <cmath>
-#include <cstring>
 #include <iostream>
 #include <memory>
 #include <stdexcept>
@@ -221,66 +220,3 @@ class Power : public Binary {
     // Implementation of evaluate for Power node.
     double evaluate() const override { return std::pow(left->evaluate(), right->evaluate()); }
 };
-
-// Static initialization of variableTable in Identifier class.
-std::unordered_map<std::string, double> Identifier::variableTable;
-
-#ifdef ENABLE_TESTS
-// Function to run a test expression evaluation.
-void runTest() {
-    // Test with a complex expression: (2 * (a + b)) / (c - 1) ^ (d + 1)
-    Identifier::setVariable("a", 3.0);
-    Identifier::setVariable("b", 1.0);
-    Identifier::setVariable("c", 5.0);
-    Identifier::setVariable("d", 2.0);
-
-    std::unique_ptr<const ASTNode> variableA = std::make_unique<Identifier>("a");
-    std::unique_ptr<const ASTNode> variableB = std::make_unique<Identifier>("b");
-    std::unique_ptr<const ASTNode> variableC = std::make_unique<Identifier>("c");
-    std::unique_ptr<const ASTNode> variableD = std::make_unique<Identifier>("d");
-
-    std::unique_ptr<const ASTNode> expression = std::make_unique<Divide>(
-        std::make_unique<Multiply>(std::make_unique<Constant>(2.0),
-                                   std::make_unique<Add>(std::move(variableA), std::move(variableB))),
-        std::make_unique<Power>(std::make_unique<Subtract>(std::move(variableC), std::make_unique<Constant>(1.0)),
-                                std::make_unique<Add>(std::move(variableD), std::make_unique<Constant>(1.0))));
-
-    // Evaluate the expression
-    double result = expression->evaluate();
-
-    // Expected result: (2 * (3 + 1)) / (5 - 1) ^ (2 + 1) = 8 / 4 ^ 3 = 8 / 64 =
-    // 0.125
-    assert(result == 0.125);
-
-    std::cout << "Test passed successfully. Result: " << result << std::endl;
-
-    // Clear variables for the next test
-    Identifier::clearVariables();
-}
-#endif // ENABLE_TESTS
-
-// Function to print the help message.
-void printHelpMessage(const char *programName) {
-    std::cout << "Usage: " << programName << " [--run-test]\n"
-              << "Options:\n"
-              << "  --run-test  Run the test for the expression evaluation code.\n"
-              << "              This option should be used without any additional "
-                 "arguments.\n"
-              << "              Example: " << programName << " --run-test\n";
-}
-
-// Main function
-int main(int argc, char *argv[]) {
-    // Check if the "--run-test" argument is provided
-    if (argc == 2 && std::strcmp(argv[1], "--run-test") == 0) {
-#ifdef ENABLE_TESTS
-        // Run the test if ENABLE_TESTS is defined
-        runTest();
-#endif // ENABLE_TESTS
-    } else {
-        // Print help message if no valid arguments are provided
-        printHelpMessage(argv[0]);
-    }
-
-    return 0;
-}