test: integration tests (#40)

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

tests/README.md

@@ -0,0 +1,19 @@
+# Tests
+
+Add one test file per scenario. You can run them in isolation with:
+
+```bash
+node tests/post-token-set.test.js
+```
+
+All tests are run together in [tests/index.js](index.js), which can be execauted with ava
+
+```
+npx ava tests/index.js
+```
+
+or with npm
+
+```
+npm test
+```

tests/index.js

@@ -0,0 +1,14 @@
+import { readdirSync } from "node:fs";
+
+import { execa } from "execa";
+import test from "ava";
+
+const tests = readdirSync("tests").filter((file) => file.endsWith(".test.js"));
+
+for (const file of tests) {
+  test(file, async (t) => {
+    const { stderr, stdout } = await execa("node", [`tests/${file}`]);
+    t.snapshot(stderr, "stderr");
+    t.snapshot(stdout, "stdout");
+  });
+}

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");

tests/post-token-unset.test.js

@@ -0,0 +1,5 @@
+// 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
+delete process.env.STATE_token;
+
+await import("../post.js");

tests/snapshots/index.js.md

@@ -0,0 +1,25 @@
+# Snapshot report for `tests/index.js`
+
+The actual snapshot is saved in `index.js.snap`.
+
+Generated by [AVA](https://avajs.dev).
+
+## post-token-set.test.js
+
+> stderr
+
+    ''
+
+> stdout
+
+    'Token revoked'
+
+## post-token-unset.test.js
+
+> stderr
+
+    ''
+
+> stdout
+
+    'Token is not set'