test: the sub-view census reads each source once

Read three times, the scan ran past the 5 s test timeout when the gate
loaded the machine.

frontend/src/moduleUrl.contract.test.ts

@@ -423,12 +423,14 @@ describe("module URL keys", () => {
       });
     const named = new Set(["MODE_URL", "PLEX_SUB_URL"]);
     const unnamed = (text: string) => handed(text).filter((arg) => !named.has(arg));
+    // Each source read once: read three times, the scan ran past the test timeout under a loaded gate.
     const files = sources(SRC).filter(
       (f) => !relative(SRC, f).split("\\").join("/").startsWith("lib/history"),
     );
-    expect(files.flatMap((f) => unnamed(readFileSync(f, "utf8")))).toEqual([]);
+    const texts = files.map((f) => readFileSync(f, "utf8"));
+    expect(texts.flatMap(unnamed)).toEqual([]);
     // The call sites are seen (a scan of none would pass)…
-    expect(new Set(files.flatMap((f) => handed(readFileSync(f, "utf8"))))).toEqual(named);
+    expect(new Set(texts.flatMap(handed))).toEqual(named);
     // …and the check tells an inline definition from a named one.
     expect(unnamed('useHistorySubview(sub, { key: "zz", encode, decode })')).toEqual([
       '{ key: "zz", encode, decode }',
@@ -442,7 +444,7 @@ describe("module URL keys", () => {
     ]);
     // Under another name it is a call no scan sees.
     const aliased = (text: string) => /\buseHistorySubview\s+as\b/.test(text);
-    expect(files.filter((f) => aliased(readFileSync(f, "utf8")))).toEqual([]);
+    expect(files.filter((_f, i) => aliased(texts[i]!))).toEqual([]);
     expect(aliased('import { useHistorySubview as useSub } from "./history";')).toBe(true);
   });