add method to filter changes by given scopes

__tests__/filter.test.ts

@@ -1,6 +1,6 @@
 import {expect, test} from '@jest/globals'
 import {Change, Changes} from '../src/schemas'
-import {filterChangesBySeverity} from '../src/filter'
+import {filterChangesBySeverity, filterChangesByScopes} from '../src/filter'
 
 let npmChange: Change = {
   manifest: 'package.json',
@@ -59,3 +59,16 @@ test('it properly filters changes by severity', async () => {
   result = filterChangesBySeverity('critical', changes)
   expect(changes).toEqual([npmChange, rubyChange])
 })
+
+test('it properly filters changes by scope', async () => {
+  const changes = [npmChange, rubyChange]
+
+  let result = filterChangesByScopes(['runtime'], changes)
+  expect(result).toEqual([npmChange])
+
+  result = filterChangesByScopes(['development'], changes)
+  expect(result).toEqual([rubyChange])
+
+  result = filterChangesByScopes(['runtime', 'development'], changes)
+  expect(result).toEqual([npmChange, rubyChange])
+})