Intuitive DSL for Java

/*
 * This file is part of the Intuitive DSL project.
 * Copyright (c) 2026 DBA Labs - Switzerland. All rights reserved.
 *
 * This program is dual-licensed under a commercial license and the AGPLv3.
 * For commercial licensing, contact us at [email protected] or visit https://www.dbalabs.ch.
 *
 * AGPLv3 licensing:
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, version 3 (19 November 2007).
 *
 * 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <https://www.gnu.org/licenses/agpl-3.0.html>.
 */

package ch.dbalabs.intuitivedsl.parser;

import ch.dbalabs.intuitivedsl.exception.DslSyntaxException;
import org.junit.jupiter.api.Test;

import java.util.List;

import static org.assertj.core.api.Assertions.assertThat;
import static org.assertj.core.api.Assertions.assertThatThrownBy;

/**
 * Unit tests for the Lexer component.
 *
 * @author DBA Labs
 */
class LexerTest {

    @Test
    void shouldTokenizeWordsStringsAndDelimitersProperly() {
        // Arrange
        Lexer lexer = new Lexer();
        String input = "SHOW 'mon test' ;";

        // Act
        List<Token> tokens = lexer.tokenize(input);

        // Assert
        // We expect 4 tokens: WORD, STRING, DELIMITER, and the mandatory EOF
        assertThat(tokens).hasSize(4);

        assertThat(tokens.get(0))
                .extracting(Token::value, Token::type)
                .containsExactly("SHOW", TokenType.WORD);

        // The quotes should be stripped from the string value
        assertThat(tokens.get(1))
                .extracting(Token::value, Token::type)
                .containsExactly("mon test", TokenType.STRING);

        assertThat(tokens.get(2))
                .extracting(Token::value, Token::type)
                .containsExactly(";", TokenType.DELIMITER);

        assertThat(tokens.get(3).type()).isEqualTo(TokenType.EOF);
    }

    @Test
    void shouldHandleEscapedQuotesInStringLiterals() {
        // Arrange
        Lexer lexer = new Lexer();
        String input = "INSERT 'O''Reilly' ;";

        // Act
        List<Token> tokens = lexer.tokenize(input);

        // Assert
        assertThat(tokens.get(1))
                .extracting(Token::value, Token::type)
                .containsExactly("O'Reilly", TokenType.STRING);
    }

    @Test
    void shouldThrowExceptionOnUnclosedStringLiteral() {
        // Arrange
        Lexer lexer = new Lexer();
        String input = "SHOW 'unclosed string ;";

        // Act & Assert
        assertThatThrownBy(() -> lexer.tokenize(input))
                .isInstanceOf(DslSyntaxException.class)
                .satisfies(e -> {
                    DslSyntaxException ex = (DslSyntaxException) e;
                    assertThat(ex.getExpectedPossibilities()).contains("closing quote (')");
                });
    }

}