Fixes #120 Artifacts can be removed even when new ones aren't provided

__tests__/ArtifactDestroyer.test.ts

@@ -0,0 +1,90 @@
+import {Artifact} from "../src/Artifact"
+import {GithubArtifactUploader} from "../src/ArtifactUploader"
+import {Releases} from "../src/Releases";
+import {RequestError} from '@octokit/request-error'
+import {GithubArtifactDestroyer} from "../src/ArtifactDestroyer";
+
+const releaseId = 100
+
+const deleteMock = jest.fn()
+const listArtifactsMock = jest.fn()
+
+
+describe('ArtifactDestroyer', () => {
+    beforeEach(() => {
+        deleteMock.mockClear()
+        listArtifactsMock.mockClear()
+    })
+
+    it('destroys all artifacts', async () => {
+        mockListWithAssets()
+        mockDeleteSuccess()
+        const destroyer = createDestroyer()
+
+        await destroyer.destroyArtifacts(releaseId)
+
+        expect(deleteMock).toBeCalledTimes(2)
+    })
+
+    it('destroys nothing when no artifacts found', async () => {
+        mockListWithoutAssets()
+        const destroyer = createDestroyer()
+
+        await destroyer.destroyArtifacts(releaseId)
+
+        expect(deleteMock).toBeCalledTimes(0)
+    })
+
+    it('throws when delete call fails', async () => {
+        mockListWithAssets()
+        mockDeleteError()
+        const destroyer = createDestroyer()
+        
+        expect.hasAssertions()
+        try {
+            await destroyer.destroyArtifacts(releaseId)
+        } catch (error) {
+            expect(error).toEqual("error")
+        }
+    })
+
+    function createDestroyer(): GithubArtifactDestroyer {
+        const MockReleases = jest.fn<Releases, any>(() => {
+            return {
+                create: jest.fn(),
+                deleteArtifact: deleteMock,
+                getByTag: jest.fn(),
+                listArtifactsForRelease: listArtifactsMock,
+                listReleases: jest.fn(),
+                update: jest.fn(),
+                uploadArtifact: jest.fn()
+            }
+        })
+        return new GithubArtifactDestroyer(new MockReleases())
+    }
+
+    function mockDeleteError(): any {
+        deleteMock.mockRejectedValue("error")
+    }
+
+    function mockDeleteSuccess(): any {
+        deleteMock.mockResolvedValue({})
+    }
+
+    function mockListWithAssets() {
+        listArtifactsMock.mockResolvedValue([
+            {
+                name: "art1",
+                id: 1
+            },
+            {
+                name: "art2",
+                id: 2
+            }
+        ])
+    }
+
+    function mockListWithoutAssets() {
+        listArtifactsMock.mockResolvedValue([])
+    }
+});