feat(test): use host-aware local full-suite defaults (#65264)

* feat(test): use host-aware local full-suite defaults

* fix(test): remove undefined local profile host info

test/scripts/vitest-local-scheduling.test.ts

@@ -0,0 +1,56 @@
+import { describe, expect, it } from "vitest";
+import {
+  resolveLocalFullSuiteProfile,
+  resolveLocalVitestScheduling,
+  shouldUseLargeLocalFullSuiteProfile,
+} from "../../scripts/lib/vitest-local-scheduling.mjs";
+
+describe("vitest local full-suite profile", () => {
+  it("selects the large local profile on roomy hosts that are not throttled", () => {
+    const env = {};
+    const hostInfo = {
+      cpuCount: 14,
+      loadAverage1m: 0,
+      totalMemoryBytes: 48 * 1024 ** 3,
+    };
+
+    expect(resolveLocalVitestScheduling(env, hostInfo, "threads")).toEqual({
+      maxWorkers: 6,
+      fileParallelism: true,
+      throttledBySystem: false,
+    });
+    expect(shouldUseLargeLocalFullSuiteProfile(env, hostInfo)).toBe(true);
+    expect(resolveLocalFullSuiteProfile(env, hostInfo)).toEqual({
+      shardParallelism: 10,
+      vitestMaxWorkers: 2,
+    });
+  });
+
+  it("keeps the smaller local profile when the host is already throttled", () => {
+    const hostInfo = {
+      cpuCount: 14,
+      loadAverage1m: 14,
+      totalMemoryBytes: 48 * 1024 ** 3,
+    };
+
+    expect(shouldUseLargeLocalFullSuiteProfile({}, hostInfo)).toBe(false);
+    expect(resolveLocalFullSuiteProfile({}, hostInfo)).toEqual({
+      shardParallelism: 4,
+      vitestMaxWorkers: 1,
+    });
+  });
+
+  it("never selects the large local profile in CI", () => {
+    const hostInfo = {
+      cpuCount: 14,
+      loadAverage1m: 0,
+      totalMemoryBytes: 48 * 1024 ** 3,
+    };
+
+    expect(shouldUseLargeLocalFullSuiteProfile({ CI: "true" }, hostInfo)).toBe(false);
+    expect(resolveLocalFullSuiteProfile({ CI: "true" }, hostInfo)).toEqual({
+      shardParallelism: 4,
+      vitestMaxWorkers: 1,
+    });
+  });
+});