test: make vitest worker caps deterministic

src/infra/vitest-config.test.ts

@@ -7,12 +7,6 @@ import baseConfig, {
 } from "../../vitest.config.ts";
 import { parseVitestProcessStats } from "../../vitest.system-load.ts";
 
-const idleVitestStats = {
-  otherVitestRootCount: 0,
-  otherVitestWorkerCount: 0,
-  otherVitestCpuPercent: 0,
-} as const;
-
 describe("resolveLocalVitestMaxWorkers", () => {
   it("uses a moderate local worker cap on larger hosts", () => {
     expect(
@@ -26,7 +20,6 @@ describe("resolveLocalVitestMaxWorkers", () => {
           totalMemoryBytes: 64 * 1024 ** 3,
         },
         "threads",
-        idleVitestStats,
       ),
     ).toBe(6);
   });
@@ -43,7 +36,6 @@ describe("resolveLocalVitestMaxWorkers", () => {
           totalMemoryBytes: 128 * 1024 ** 3,
         },
         "threads",
-        idleVitestStats,
       ),
     ).toBe(2);
   });
@@ -60,7 +52,6 @@ describe("resolveLocalVitestMaxWorkers", () => {
           totalMemoryBytes: 128 * 1024 ** 3,
         },
         "threads",
-        idleVitestStats,
       ),
     ).toBe(3);
   });
@@ -75,7 +66,6 @@ describe("resolveLocalVitestMaxWorkers", () => {
           totalMemoryBytes: 16 * 1024 ** 3,
         },
         "threads",
-        idleVitestStats,
       ),
     ).toBe(2);
   });
@@ -90,7 +80,6 @@ describe("resolveLocalVitestMaxWorkers", () => {
           totalMemoryBytes: 128 * 1024 ** 3,
         },
         "threads",
-        idleVitestStats,
       ),
     ).toBe(8);
   });
@@ -105,7 +94,6 @@ describe("resolveLocalVitestMaxWorkers", () => {
           totalMemoryBytes: 128 * 1024 ** 3,
         },
         "threads",
-        idleVitestStats,
       ),
     ).toBe(2);
   });
@@ -120,54 +108,43 @@ describe("resolveLocalVitestMaxWorkers", () => {
           totalMemoryBytes: 256 * 1024 ** 3,
         },
         "threads",
-        idleVitestStats,
       ),
     ).toBe(12);
   });
 });
 
 describe("resolveLocalVitestScheduling", () => {
-  it("scales back to half capacity when other Vitest work is already consuming most cores", () => {
+  it("scales back to half capacity when the host load is already saturated", () => {
     expect(
       resolveLocalVitestScheduling(
         {},
         {
           cpuCount: 16,
-          loadAverage1m: 0.5,
+          loadAverage1m: 16,
           totalMemoryBytes: 128 * 1024 ** 3,
         },
         "threads",
-        {
-          otherVitestRootCount: 2,
-          otherVitestWorkerCount: 12,
-          otherVitestCpuPercent: 1200,
-        },
       ),
     ).toEqual({
-      maxWorkers: 4,
+      maxWorkers: 2,
       fileParallelism: true,
       throttledBySystem: true,
     });
   });
 
-  it("keeps big hosts parallel under moderate contention", () => {
+  it("keeps big hosts parallel under moderate host contention", () => {
     expect(
       resolveLocalVitestScheduling(
         {},
         {
           cpuCount: 16,
-          loadAverage1m: 0.5,
+          loadAverage1m: 12,
           totalMemoryBytes: 128 * 1024 ** 3,
         },
         "threads",
-        {
-          otherVitestRootCount: 1,
-          otherVitestWorkerCount: 7,
-          otherVitestCpuPercent: 700,
-        },
       ),
     ).toEqual({
-      maxWorkers: 6,
+      maxWorkers: 5,
       fileParallelism: true,
       throttledBySystem: true,
     });
@@ -185,7 +162,6 @@ describe("resolveLocalVitestScheduling", () => {
           totalMemoryBytes: 128 * 1024 ** 3,
         },
         "threads",
-        idleVitestStats,
       ),
     ).toEqual({
       maxWorkers: 8,