fix: allow heavyweight docker lanes at low parallelism

test/scripts/docker-all-scheduler.test.ts

@@ -0,0 +1,138 @@
+import { describe, expect, it } from "vitest";
+import {
+  canStartSchedulerLane,
+  describeDockerSchedulerLimits,
+} from "../../scripts/test-docker-all.mjs";
+
+const limits = {
+  resourceLimits: {
+    docker: 2,
+    npm: 2,
+  },
+  weightLimit: 2,
+};
+
+function activePool({
+  count = 0,
+  resources = {},
+  weight = 0,
+}: {
+  count?: number;
+  resources?: Record<string, number>;
+  weight?: number;
+} = {}) {
+  return {
+    count,
+    resources: new Map(Object.entries(resources)),
+    weight,
+  };
+}
+
+describe("scripts/test-docker-all scheduler", () => {
+  it("allows an overweight lane to start alone under low parallelism", () => {
+    expect(
+      canStartSchedulerLane(
+        {
+          name: "install-e2e",
+          resources: ["npm"],
+          weight: 4,
+        },
+        activePool(),
+        2,
+        limits,
+      ),
+    ).toBe(true);
+  });
+
+  it("does not co-schedule another lane while an overweight lane is active", () => {
+    expect(
+      canStartSchedulerLane(
+        {
+          name: "package-update",
+          resources: ["npm"],
+          weight: 1,
+        },
+        activePool({
+          count: 1,
+          resources: {
+            docker: 4,
+            npm: 4,
+          },
+          weight: 4,
+        }),
+        2,
+        limits,
+      ),
+    ).toBe(false);
+  });
+
+  it("preserves the parallelism count cap", () => {
+    expect(
+      canStartSchedulerLane(
+        {
+          name: "package-update",
+          resources: ["npm"],
+          weight: 1,
+        },
+        activePool({
+          count: 2,
+          resources: {
+            docker: 1,
+            npm: 1,
+          },
+          weight: 1,
+        }),
+        2,
+        limits,
+      ),
+    ).toBe(false);
+  });
+
+  it("keeps resource and weight limits as co-scheduling limits", () => {
+    expect(
+      canStartSchedulerLane(
+        {
+          name: "npm-smoke",
+          resources: ["npm"],
+          weight: 1,
+        },
+        activePool({
+          count: 1,
+          resources: {
+            docker: 1,
+            npm: 1,
+          },
+          weight: 1,
+        }),
+        2,
+        limits,
+      ),
+    ).toBe(true);
+
+    expect(
+      canStartSchedulerLane(
+        {
+          name: "npm-heavy",
+          resources: ["npm"],
+          weight: 2,
+        },
+        activePool({
+          count: 1,
+          resources: {
+            docker: 1,
+            npm: 1,
+          },
+          weight: 1,
+        }),
+        2,
+        limits,
+      ),
+    ).toBe(false);
+  });
+
+  it("describes effective scheduler limits for operator errors", () => {
+    expect(describeDockerSchedulerLimits(2, limits)).toBe(
+      "parallelism=2 weightLimit=2 resources=docker=2 npm=2",
+    );
+  });
+});