A few suggestions / modifications / fixes

It seems you've accidentally swapped the implementation and the test file :)

The overall comment describing the algorithm (VERY nice doc, by the way) is not "proper" JSdoc => only one leading asterisk. It's generally considered good style to start a comment block (both JSdoc and regular comments) with a single, short sentence.

Further down, there were some git hiccups, most likely caused by merge conflicts?

Author: defaude

Maths/test/FermatPrimalityTest.js renamed to Maths/FermatPrimalityTest.js

@@ -1,6 +1,7 @@
-/**
- * The Fermat primality test is a probabilistic test to determine whether a number is a probable prime. It relies on
- * Fermat's Little Theorem, which states that if p is prime and a is not divisible by p, then
+/*
+ * The Fermat primality test is a probabilistic test to determine whether a number is a probable prime.
+ *
+ * It relies on Fermat's Little Theorem, which states that if p is prime and a is not divisible by p, then
  *
  *     a^(p - 1) % p = 1
  *
@@ -53,28 +54,20 @@ const modularExponentiation = (base, exponent, modulus) => {
 }
 
 /**
- *  Test if a given number n is prime or not.
+ * Test if a given number n is prime or not.
  *
  * @param {number} n The number to check for primality
  * @param {number} numberOfIterations The number of times to apply Fermat's Little Theorem
  * @returns True if prime, false otherwise
  */
 const fermatPrimeCheck = (n, numberOfIterations) => {
   // first check for corner cases
-<<<<<<< HEAD
   if (n <= 1 || n === 4) return false
-=======
-  if (n <= 1 || n == 4) return false
->>>>>>> 951c7258323a057041c0d128880982ddab303ee5
   if (n <= 3) return true // 2 and 3 are included here
 
   for (let i = 0; i < numberOfIterations; i++) {
     // pick a random number between 2 and n - 2
-<<<<<<< HEAD
     const randomNumber = Math.floor(Math.random() * (n - 1 - 2) + 2)
-=======
-    let randomNumber = Math.floor(Math.random() * (n - 1 - 2) + 2)
->>>>>>> 951c7258323a057041c0d128880982ddab303ee5
 
     // if a^(n - 1) % n is different than 1, n is composite
     if (modularExponentiation(randomNumber, n - 1, n) !== 1) {

Maths/FermatPrimalityTest.test.js renamed to Maths/test/FermatPrimalityTest.test.js

@@ -1,4 +1,4 @@
-import { modularExponentiation, fermatPrimeCheck } from '../FermatPrimalityTest'
+import { fermatPrimeCheck, modularExponentiation } from '../FermatPrimalityTest'
 
 describe('modularExponentiation', () => {
   it('should give the correct output for all exponentiations', () => {