Allowing dependencies works with no licenses

When using the `allow-dependencies-licenses` option, the packages listed
there should be allowed even if they have no license. This wasn't
working because the filtering for allowed dependencies was done
specifically on the list of packages that had licenses, leaving a
separate list (unfiltered) for packages with no licenses. With this
change, we filter out any changes for packages that have been allowed
_before_ we retrieve licenses.

Fixes #889

__tests__/licenses.test.ts

@@ -100,6 +100,20 @@ const complexLicenseChange: Change = {
   ]
 }
 
+const unlicensedChange: Change = {
+  change_type: 'added',
+  manifest: '.github/workflows/ci.yml',
+  ecosystem: 'actions',
+  name: 'foo-org/actions-repo/.github/workflows/some-action.yml',
+  version: '1.1.1',
+  package_url:
+    'pkg:githubactions/foo-org/actions-repo/.github/workflows/[email protected]',
+  license: null,
+  source_repository_url: 'github.com/some-repo',
+  scope: 'development',
+  vulnerabilities: []
+}
+
 jest.mock('@actions/core')
 
 const mockOctokit = {
@@ -313,4 +327,15 @@ describe('GH License API fallback', () => {
     expect(mockOctokit.rest.licenses.getForRepo).not.toHaveBeenCalled()
     expect(unlicensed.length).toEqual(0)
   })
+
+  test('it does not call licenses API if the package is excluded', async () => {
+    const {unlicensed} = await getInvalidLicenseChanges([unlicensedChange], {
+      licenseExclusions: [
+        'pkg:githubactions/foo-org/actions-repo/.github/workflows/some-action.yml'
+      ]
+    })
+
+    expect(mockOctokit.rest.licenses.getForRepo).not.toHaveBeenCalled()
+    expect(unlicensed.length).toEqual(0)
+  })
 })