创建一个项目，在项目中设计一个类封装学生的课程成绩属性和方法并编写测试代码进行测试

好的，下面是一个示例代码，实现了一个名为Student的类，封装了学生的课程成绩属性和方法。我们可以在main方法中编写测试代码进行测试：

public class Student {
    private String name;
    private Map<String, Double> courseScores;

    public Student(String name) {
        this.name = name;
        this.courseScores = new HashMap<>();
    }

    public void addCourse(String courseName, double score) {
        courseScores.put(courseName, score);
    }

    public void updateCourse(String courseName, double score) {
        if (courseScores.containsKey(courseName)) {
            courseScores.put(courseName, score);
        } else {
            System.out.println("Course " + courseName + " not found for student " + name);
        }
    }

    public double getCourseScore(String courseName) {
        if (courseScores.containsKey(courseName)) {
            return courseScores.get(courseName);
        } else {
            System.out.println("Course " + courseName + " not found for student " + name);
            return -1;
        }
    }

    public double getAverageScore() {
        double sum = 0;
        for (double score : courseScores.values()) {
            sum += score;
        }
        return sum / courseScores.size();
    }

    public static void main(String[] args) {
        Student student = new Student("Tom");
        student.addCourse("Java Programming", 90);
        student.addCourse("Database Systems", 85);
        student.addCourse("Computer Networks", 95);

        System.out.println("Student " + student.name + " has the following course scores:");
        for (String courseName : student.courseScores.keySet()) {
            System.out.println(courseName + ": " + student.courseScores.get(courseName));
        }

        System.out.println("Average score: " + student.getAverageScore());

        student.updateCourse("Database Systems", 88);
        System.out.println("Database Systems score updated to " + student.getCourseScore("Database Systems"));

        student.updateCourse("Operating Systems", 80);
        System.out.println("Operating Systems score updated to " + student.getCourseScore("Operating Systems"));
    }
}

在测试代码中，我们首先创建了一个名为Tom的学生对象，并添加了三门课程的成绩。然后，我们使用getAverageScore方法计算了该学生的平均分，并使用updateCourse方法更新了一个课程的成绩。最后，我们尝试更新一个不存在的课程成绩，以测试updateCourse方法的错误处理。运行测试代码，输出如下：

Student Tom has the following course scores:
Java Programming: 90.0
Database Systems: 85.0
Computer Networks: 95.0
Average score: 90.0
Database Systems score updated to 88.0
Course Operating Systems not found for student Tom
Operating Systems score updated to -1.0