merge: Remove duplicate helper functions in cache tests. (#933)

* refactor: added one implementation of fibonacciCahce

* chore: move union function

* chore: renamed the cacheTest file

Cache/test/cacheTest.js

@@ -0,0 +1,37 @@
+/**
+ * @function fibonacciCache
+ * @description - this is a cached variant of fib number
+ * @param {number} n  - Real number (n > -1)
+ * @param {Object} cache
+ * @returns {number}
+ */
+export const fibonacciCache = (n, cache = null) => {
+  if (cache) {
+    const value = cache.get(n)
+
+    if (value !== null) {
+      return value
+    }
+  }
+
+  if (n === 1 || n === 2) {
+    return 1
+  }
+
+  const result = fibonacciCache(n - 1, cache) + fibonacciCache(n - 2, cache)
+
+  cache && cache.set(n, result)
+
+  return result
+}
+
+/**
+ * @title implementation of union function
+ * @param {Set} sets
+ * @return {new Set}
+ */
+export const union = (...sets) => {
+  return new Set(
+    sets.reduce((flatArray, set) => [...flatArray, ...set], [])
+  )
+}