very basic parser of let statements

test/parser.cpp

@@ -0,0 +1,107 @@
+#include "parser/parser.hpp"
+
+#include "ast/ast.hpp"
+#include "ast/statements/let.hpp"
+#include "lexer/lexer.hpp"
+
+#include <doctest.h>
+#include <iostream>
+#include <sstream>
+
+void test_let_statement(ast::statement* stmt, const std::string name) {
+    REQUIRE(stmt->token_literal() == "let");
+    ast::let* let_stmt = dynamic_cast<ast::let*>(stmt);
+    REQUIRE_MESSAGE(
+        let_stmt != nullptr,
+        "Couldn't cast statement to a let statement"
+    );
+
+    REQUIRE(let_stmt->name->value == name);
+    REQUIRE(let_stmt->name->token_literal() == name);
+}
+
+void checkParserErrors(const std::vector<std::string>& errors) {
+    if (errors.empty())
+        return;
+
+    std::cerr << "parser has " << errors.size() << " errors:\n";
+    for (const auto& msg : errors)
+        std::cerr << "parser error: \"" << msg << "\"\n";
+
+    // Use doctest's FAIL macro to immediately stop
+    FAIL_CHECK("Parser had errors. See stderr for details.");
+}
+
+TEST_CASE("Malformed let statement (checking for memory leaks)") {
+    SUBCASE("Second token not identifier") {
+        std::stringstream input("\
+let 5 = 5;\
+");
+
+        lexer::lexer l{input};
+        parser::parser p{l};
+
+        ast::program* program = p.parse_program();
+        REQUIRE_MESSAGE(
+            program != nullptr,
+            "parse_program() returned a null pointer"
+        );
+        REQUIRE(program->statements.size() == 0);
+        delete program;
+    }
+
+    SUBCASE("Third token not '='") {
+        std::stringstream input("\
+let five ! 5;\
+");
+
+        lexer::lexer l{input};
+        parser::parser p{l};
+
+        ast::program* program = p.parse_program();
+        REQUIRE_MESSAGE(
+            program != nullptr,
+            "parse_program() returned a null pointer"
+        );
+        REQUIRE(program->statements.size() == 0);
+        delete program;
+    }
+}
+
+TEST_CASE("Parse let statement") {
+    std::stringstream input("\
+let x = 5;\
+let y = 10;\
+let foobar = 103213;\
+");
+
+    lexer::lexer l{input};
+    parser::parser p{l};
+
+    ast::program* program = p.parse_program();
+
+    REQUIRE_MESSAGE(
+        program != nullptr,
+        "parse_program() returned a null pointer"
+    );
+    REQUIRE(program->statements.size() == 3);
+
+    struct test {
+        std::string expected_identifier;
+    };
+
+    test tests[]{
+        "x",
+        "y",
+        "foobar",
+    };
+
+    int i = 0;
+    for (const auto& t : tests) {
+        ast::statement* stmt = program->statements[i++];
+
+        test_let_statement(stmt, t.expected_identifier);
+    }
+
+    delete program;
+}