feat: add unit tests for collection utils (#2564)

Closes #2406

packages/xrpl/test/utils/collections.test.ts

@@ -0,0 +1,27 @@
+import { groupBy, omitBy } from '../../src/utils/collections'
+
+describe('Collection Utils:', () => {
+  // Inspired from tests at https://github.com/lodash/lodash/blob/main/test/groupBy.spec.js
+  describe('groupBy', () => {
+    const array = [6.1, 4.2, 6.3]
+
+    it('should transform keys by `iteratee`', () => {
+      const actual = groupBy(array, Math.floor)
+      expect(actual).toEqual({ 4: [4.2], 6: [6.1, 6.3] })
+    })
+
+    it('should transform keys by `iteratee` that returns strings', () => {
+      const actual = groupBy(array, (item) => Math.floor(item).toString())
+      expect(actual).toEqual({ '4': [4.2], '6': [6.1, 6.3] })
+    })
+  })
+
+  // Taken from https://github.com/lodash/lodash/blob/main/test/omitBy.spec.js
+  describe('omitBy', () => {
+    it('should work with a predicate argument', () => {
+      const object = { aa: 1, bb: 2, cc: 3, dd: 4 }
+      const actual = omitBy(object, (num) => num !== 2 && num !== 4)
+      expect(actual).toEqual({ bb: 2, dd: 4 })
+    })
+  })
+})