ShellSortTest

package ds.shell;

import static org.junit.jupiter.api.Assertions.*;

import java.io.File;
import java.io.IOException;
import java.util.Scanner;

import org.junit.jupiter.api.AfterAll;
import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.Test;

class ShellSortTest {
    static Student[] students;
    static String originalPath = "/path/to/students.csv";
    static String sortedPath = "/path/to/sorted_students.csv";

    @BeforeAll
    static void setUpBeforeClass() throws Exception {
        students = TextFileParser.readFile(originalPath);
    }

    @AfterAll
    static void tearDownAfterClass() throws Exception {
        students = null;
    }

    @Test
    void testReadsFromFile() throws IOException {
        assertNotNull(students);
        assertTrue(students[0] instanceof Student);
        assertEquals(1000000, students.length);
    }

    @Test
    void testSortsStudents() {
        ShellSort.sort(students);
        assertEquals(100, students[0].getStudentID());
        assertEquals(101, students[1].getStudentID());
        assertEquals(102, students[2].getStudentID());
        assertEquals(20110396, students[543823].getStudentID());
        assertEquals(10185139, students[385139].getStudentID());
        assertEquals(30333094, students[999998].getStudentID());
        assertEquals(30333095, students[999999].getStudentID());
    }

    @Test
    void testWritesToFile() throws IOException {
        new File(sortedPath).delete(); // delete old file

        ShellSort.sort(students);
        TextFileParser.writeFile(students, sortedPath);
        assertTrue(new File(sortedPath).exists());

        Scanner scanner = new Scanner(new File(sortedPath));

        /* Check if students are loaded correctly from file lines */
        String line = scanner.nextLine();
        String[] parts = line.split(";");
        Student s1 = new Student(Integer.parseInt(parts[0]), parts[1], parts[2],
                                 parts[3], parts[4], Integer.parseInt(parts[5]));
        assertEquals(100, s1.getStudentID());

        scanner.close();
    }

    @Test
    void testStudentsAreComparable() {
        Student s1 = new Student(1, "A", "01-01-1997", "IBU", "IT", 2018);
        Student s2 = new Student(2, "B", "31-12-1997", "IBU", "IT", 2018);

        assertTrue(s2.compareTo(s1) > 0);
        assertTrue(s1.compareTo(s2) < 0);
        assertTrue(s1.compareTo(s1) == 0);
    }

}