test: integration tests (#40)

Co-authored-by: Gregor Martynus <39992+gr2m@users.noreply.github.com>

tests/post-token-set.test.js

@@ -0,0 +1,25 @@
+import { MockAgent, setGlobalDispatcher } from "undici";
+
+// state variables are set as environment variables with the prefix STATE_
+// https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#sending-values-to-the-pre-and-post-actions
+process.env.STATE_token = "secret123";
+
+const mockAgent = new MockAgent();
+
+setGlobalDispatcher(mockAgent);
+
+// Provide the base url to the request
+const mockPool = mockAgent.get("https://api.github.com");
+
+// intercept the request
+mockPool
+  .intercept({
+    path: "/installation/token",
+    method: "DELETE",
+    headers: {
+      authorization: "token secret123",
+    },
+  })
+  .reply(204);
+
+await import("../post.js");