chore: import upstream snapshot with attribution

apps/webapp/test/mollifierDrainerWorker.test.ts

@@ -0,0 +1,85 @@
+import { describe, expect, it, vi } from "vitest";
+
+// Importing `~/v3/mollifier/mollifierDrainer.server` (below) transitively
+// loads `~/v3/runEngine.server`, whose top-level `singleton(...)` call
+// eagerly constructs a RunEngine. That spins up Prisma + Redis workers
+// that try to connect to localhost — which in CI (no PG, no Redis)
+// produces an unhandled `PrismaClientInitializationError` that fails
+// the test run even though the assertions all pass. Mocking the
+// runEngine module short-circuits the singleton so no worker starts.
+vi.mock("~/v3/runEngine.server", () => ({ engine: {} }));
+// Same problem: prisma.server.ts's top-level singleton tries to open a
+// PG client. The test never makes a query; an empty stub is enough.
+vi.mock("~/db.server", () => ({ prisma: {}, $replica: {} }));
+
+import { MollifierConfigurationError } from "~/v3/mollifier/mollifierDrainer.server";
+import { initMollifierDrainerWorker } from "~/v3/mollifierDrainerWorker.server";
+
+// Pins the error-classification policy inside the bootstrap's catch:
+// deterministic misconfig errors propagate (so a deploy fails loud
+// rather than silently disabling the drainer), and anything else is
+// logged-and-swallowed (so a transient Redis blip during boot doesn't
+// take the whole webapp down). The corresponding production-path
+// integration is the call at `entry.server.tsx`: a sync throw out of
+// `initMollifierDrainerWorker` propagates to the module top level
+// BEFORE `process.on("uncaughtException", ...)` is registered, so Node
+// crashes with a stack trace and exit code 1 — which is exactly what we
+// want from the orchestrator's health-check perspective.
+describe("initMollifierDrainerWorker error classification", () => {
+  it("rethrows MollifierConfigurationError so the process can crash on misconfig", () => {
+    const misconfig = new MollifierConfigurationError(
+      "TRIGGER_MOLLIFIER_DRAIN_SHUTDOWN_TIMEOUT_MS must be at least 1000ms below GRACEFUL_SHUTDOWN_TIMEOUT"
+    );
+
+    expect(() =>
+      initMollifierDrainerWorker({
+        isEnabled: () => true,
+        getDrainer: () => {
+          throw misconfig;
+        },
+      })
+    ).toThrow(MollifierConfigurationError);
+  });
+
+  it("rethrows when the error carries the marker name even if instanceof fails (dev-realm hot-reload fallback)", () => {
+    // Simulate the cross-realm case where the consumer's instanceof
+    // check sees a different class instance from the one the throw
+    // site used. The bootstrap's `.name === "MollifierConfigurationError"`
+    // fallback must catch this so dev hot-reload doesn't silently
+    // suppress misconfig errors.
+    const cousin = new Error("buffer not initialised");
+    cousin.name = "MollifierConfigurationError";
+
+    expect(() =>
+      initMollifierDrainerWorker({
+        isEnabled: () => true,
+        getDrainer: () => {
+          throw cousin;
+        },
+      })
+    ).toThrow(cousin);
+  });
+
+  it("swallows non-configuration errors so transient init failures don't take the webapp down", () => {
+    expect(() =>
+      initMollifierDrainerWorker({
+        isEnabled: () => true,
+        getDrainer: () => {
+          throw new Error("transient redis blip during buffer init");
+        },
+      })
+    ).not.toThrow();
+  });
+
+  it("is a no-op when the drainer is disabled for this replica", () => {
+    let factoryCalled = false;
+    initMollifierDrainerWorker({
+      isEnabled: () => false,
+      getDrainer: () => {
+        factoryCalled = true;
+        return null;
+      },
+    });
+    expect(factoryCalled).toBe(false);
+  });
+});