feat: add student record

[sumimaria]

📝 Description

This PR adds a new Student class that models a student's marks and provides utility methods:

• total() – calculates the total marks across all subjects
• passed() – checks whether the student has passed all subjects (marks ≥ 40)

It also includes a dedicated test file (student.test.js) using Node’s built-in testing framework (node:test) and strict assertions to validate functionality.

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🔗 Related Issue

Fixes #
(e.g., Fixes #7 — Add basic Student class with test coverage)

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🧩 Type of Change

• ✨ New feature — added a Student class with methods
• ✅ Test addition — introduced test cases using Node’s built-in test module
• 🧾 Documentation update
• 🧹 Code refactoring
• 🐞 Bug fix
• ⚡ Performance improvement

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🧠 Changes Made

• Added student.js with the Student class
  • total() → returns sum of marks using reduce()
  • passed() → returns true only if all marks ≥ 40 using every()
• Added student.test.js for automated testing
  • Tests for total marks calculation
  • Tests for pass/fail conditions
• Ensured ES module compatibility via export/import

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🧪 Testing

How to Run Tests

1. Ensure Node.js ≥ v18 is installed.
2. Run the test command:

   node --test student.test.js

[tr1sm0s1n]

No PR to main.