Add Fibonacci sequence utility

.gitignore

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+node_modules/

src/utils/fibonacci.js

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+/**
+ * Author: Daniella Bertoldi and AI agents
+ * Date: 2 June 2026
+ * File: fibonacci.js
+ * Description: This script generates a Fibonacci sequence.
+ */
+'use strict';
+
+// The fibonacci function generates a Fibonacci sequence up to a given number of terms
+function fibonacci(n) {
+
+  // If the number is less than 0, throw an error
+  if (n < 0) {
+    throw new Error('Fibonacci sequence cannot be generated for negative numbers');
+  }
+
+  // If the number is 0, return an empty array
+  if (n === 0) {
+    return [];
+  }
+
+  // If the number is 1, return the first Fibonacci number
+  if (n === 1) {
+    return [0];
+  }
+
+  // Start the sequence with the first two Fibonacci numbers
+  const sequence = [0, 1];
+
+  // Add the next Fibonacci numbers until the sequence reaches n terms
+  for (let i = 2; i < n; i++) {
+    sequence.push(sequence[i - 1] + sequence[i - 2]);
+  }
+
+  return sequence;
+}
+
+module.exports = { fibonacci }; // Export the fibonacci function for use in other scripts

test/utils/fibonacci.spec.js

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+/**
+ * Author: Daniella Bertoldi + AI Agents and Reserach
+ * Date: 2 June 2026
+ * File: fibonacci.spec.js
+ * Description: This script tests the fibonacci function.
+ */
+'use strict';
+
+const { fibonacci } = require('../../src/utils/fibonacci');
+
+// The describe() function is a test suite that contains one or more tests
+describe('fibonacci.js', () => {
+
+  // The it() function is a test spec that contains one or more expectations
+  it('should generate a Fibonacci sequence with 1 term', () => {
+    const result = fibonacci(1);
+    expect(result).toEqual([0]);
+  });
+
+  // The it() function is a test spec that contains one or more expectations
+  it('should generate a Fibonacci sequence with 5 terms', () => {
+    const result = fibonacci(5);
+    expect(result).toEqual([0, 1, 1, 2, 3]);
+  });
+
+  // The it() function is a test spec that contains one or more expectations
+  it('should throw an error when generating a Fibonacci sequence for a negative number', () => {
+    expect(() => fibonacci(-1)).toThrow('Fibonacci sequence cannot be generated for negative numbers');
+  });
+});