test: dedupe provider usage tests and expand coverage

src/infra/provider-usage.shared.test.ts

@@ -0,0 +1,27 @@
+import { describe, expect, it } from "vitest";
+import { clampPercent, resolveUsageProviderId, withTimeout } from "./provider-usage.shared.js";
+
+describe("provider-usage.shared", () => {
+  it("normalizes supported usage provider ids", () => {
+    expect(resolveUsageProviderId("z-ai")).toBe("zai");
+    expect(resolveUsageProviderId(" GOOGLE-ANTIGRAVITY ")).toBe("google-antigravity");
+    expect(resolveUsageProviderId("unknown-provider")).toBeUndefined();
+    expect(resolveUsageProviderId()).toBeUndefined();
+  });
+
+  it("clamps usage percents and handles non-finite values", () => {
+    expect(clampPercent(-5)).toBe(0);
+    expect(clampPercent(120)).toBe(100);
+    expect(clampPercent(Number.NaN)).toBe(0);
+    expect(clampPercent(Number.POSITIVE_INFINITY)).toBe(0);
+  });
+
+  it("returns work result when it resolves before timeout", async () => {
+    await expect(withTimeout(Promise.resolve("ok"), 100, "fallback")).resolves.toBe("ok");
+  });
+
+  it("returns fallback when timeout wins", async () => {
+    const late = new Promise<string>((resolve) => setTimeout(() => resolve("late"), 50));
+    await expect(withTimeout(late, 1, "fallback")).resolves.toBe("fallback");
+  });
+});