feat: add extensive test suite

app/api/active/handler.test.ts

@@ -0,0 +1,66 @@
+import { describe, expect, mock, test } from "bun:test";
+import { createActiveHandler } from "./handler";
+
+function dependencies() {
+  return {
+    file: {
+      exists: mock(async () => true),
+      text: mock(async () => "stored-version"),
+      write: mock(async () => {}),
+    },
+    randomUUID: mock(() => "new-version"),
+    isDevelopment: mock(() => false),
+    stream: mock(
+      async (_options: {
+        motd: { data: string; event: string };
+        signal: AbortSignal;
+      }) => new Response("stream"),
+    ),
+  };
+}
+
+describe("active handler", () => {
+  test("emits DEV without reading the version file in development", async () => {
+    const deps = dependencies();
+    deps.isDevelopment.mockReturnValue(true);
+    const request = new Request("https://buzz.test/api/active");
+    await createActiveHandler(deps)(request);
+    expect(deps.file.exists).not.toHaveBeenCalled();
+    expect(deps.stream).toHaveBeenCalledWith({
+      motd: { data: "DEV", event: "version" },
+      signal: request.signal,
+    });
+  });
+
+  test("emits an existing persisted version", async () => {
+    const deps = dependencies();
+    await createActiveHandler(deps)(
+      new Request("https://buzz.test/api/active"),
+    );
+    expect(deps.file.text).toHaveBeenCalled();
+    expect(deps.file.write).not.toHaveBeenCalled();
+    expect(deps.stream.mock.calls[0]?.[0].motd.data).toBe("stored-version");
+  });
+
+  test("persists and emits the same UUID when the file is absent", async () => {
+    const deps = dependencies();
+    deps.file.exists.mockResolvedValue(false);
+    await createActiveHandler(deps)(
+      new Request("https://buzz.test/api/active"),
+    );
+    expect(deps.randomUUID).toHaveBeenCalledTimes(1);
+    expect(deps.file.write).toHaveBeenCalledWith("new-version");
+    expect(deps.stream.mock.calls[0]?.[0].motd.data).toBe("new-version");
+  });
+
+  test("replaces an empty file with one UUID", async () => {
+    const deps = dependencies();
+    deps.file.text.mockResolvedValue("");
+    await createActiveHandler(deps)(
+      new Request("https://buzz.test/api/active"),
+    );
+    expect(deps.randomUUID).toHaveBeenCalledTimes(1);
+    expect(deps.file.write).toHaveBeenCalledWith("new-version");
+    expect(deps.stream.mock.calls[0]?.[0].motd.data).toBe("new-version");
+  });
+});