refactoring: extract sample courses in CourseTest file

src/test/java/org/example/CourseTest.java

@@ -15,6 +15,9 @@ import static org.junit.jupiter.api.Assertions.*;
  */
 class CourseTest {
     private static final String TEMP_FILE = "test_course_data.txt";
+    private static final Course sampleCourse = new Course("Math", "M101", 3);
+    private static final Course sampleCourse2 = new Course("Science", "S101", 4);
+    private static final Course sampleCourse3 = new Course("Java", "J101", 3);
 
     /**
      * Tests the printCourseInfo method of the Course class.
@@ -22,12 +25,9 @@ class CourseTest {
      */
     @Test
     void printCourseInfo() {
-        // Create a new Course object
-        Course course = new Course("Introduction to Programming", "CS101", 3);
-
         // Set up the expected output
-        String expectedCourseName = "Course Name: Introduction to Programming";
-        String expectedCourseCode = "Course Code: CS101";
+        String expectedCourseName = "Course Name: Math";
+        String expectedCourseCode = "Course Code: M101";
         String expectedCourseCredits = "Course Credits: 3";
 
         // Redirect System.out to capture printed output
@@ -36,7 +36,7 @@ class CourseTest {
         System.setOut(new PrintStream(outputStream));
 
         // Call the method to be tested
-        course.printCourseInfo();
+        sampleCourse.printCourseInfo();
 
         // Reset System.out
         System.setOut(originalOut);
@@ -60,7 +60,7 @@ class CourseTest {
     @Test
     void writeToFile() {
         // Create a new course
-        Course course = new Course("Math", "C101", 3);
+        Course course = sampleCourse;
 
         // Write course data to the temporary file
         course.writeToFile(course.getCourseName(), course.getCourseCode(), course.getCourseCredit(), TEMP_FILE);
@@ -72,7 +72,7 @@ class CourseTest {
         assertEquals(1, courses.size());
         Course readCourse = courses.get(0);
         assertEquals("Math", readCourse.getCourseName());
-        assertEquals("C101", readCourse.getCourseCode());
+        assertEquals("M101", readCourse.getCourseCode());
         assertEquals(3, readCourse.getCourseCredit());
 
         // Delete the temporary file
@@ -108,16 +108,12 @@ class CourseTest {
         deleteTempFile();
     }
 
-    /**
-     * Tests the addCourse method of the Course class.
-     * Verifies that a new course can be added to the file.
-     */
     @Test
     void addCourse() {
         // Create a new course
-        String courseName = "Math";
-        String courseCode = "C101";
-        int courseCredit = 3;
+        String courseName = sampleCourse.getCourseName();
+        String courseCode = sampleCourse.getCourseCode();
+        int courseCredit = sampleCourse.getCourseCredit();
 
         // Write course data to the temporary file
         Course.addCourse(courseName, courseCode, courseCredit, TEMP_FILE);
@@ -136,28 +132,19 @@ class CourseTest {
         deleteTempFile();
     }
 
-    /**
-     * Tests the deleteCourse method of the Course class.
-     * Verifies that a course can be deleted from the file.
-     */
     @Test
     public void testDeleteCourse() throws IOException {
-        // Prepare test data
-        Course course1 = new Course("Math", "M101", 3);
-        Course course2 = new Course("Science", "S101", 4);
-        Course course3 = new Course("Java", "J101", 4);
-
         // Write courses to the test file
         PrintWriter writer = new PrintWriter(new FileWriter(TEMP_FILE));
-        writer.println(course1.getCourseName());
-        writer.println(course1.getCourseCode());
-        writer.println(course1.getCourseCredit());
-        writer.println(course2.getCourseName());
-        writer.println(course2.getCourseCode());
-        writer.println(course2.getCourseCredit());
-        writer.println(course3.getCourseName());
-        writer.println(course3.getCourseCode());
-        writer.println(course3.getCourseCredit());
+        writer.println(sampleCourse.getCourseName());
+        writer.println(sampleCourse.getCourseCode());
+        writer.println(sampleCourse.getCourseCredit());
+        writer.println(sampleCourse2.getCourseName());
+        writer.println(sampleCourse2.getCourseCode());
+        writer.println(sampleCourse2.getCourseCredit());
+        writer.println(sampleCourse3.getCourseName());
+        writer.println(sampleCourse3.getCourseCode());
+        writer.println(sampleCourse3.getCourseCredit());
         writer.close();
 
         // Simulate user input for course deletion
@@ -174,7 +161,7 @@ class CourseTest {
         assertEquals(2, coursesAfterDeletion.size());
 
         // Check if the correct course was deleted
-        assertFalse(coursesAfterDeletion.contains(course1));
+        assertFalse(coursesAfterDeletion.contains(sampleCourse));
 
         deleteTempFile();
     }