test: tighten shared singleton and sample coverage

src/shared/global-singleton.test.ts

@@ -27,6 +27,15 @@ describe("resolveGlobalSingleton", () => {
     expect(resolveGlobalSingleton(TEST_KEY, create)).toBeUndefined();
     expect(create).toHaveBeenCalledTimes(1);
   });
+
+  it("reuses a prepopulated global value without calling the factory", () => {
+    const existing = { value: 7 };
+    const create = vi.fn(() => ({ value: 1 }));
+    (globalThis as Record<PropertyKey, unknown>)[TEST_KEY] = existing;
+
+    expect(resolveGlobalSingleton(TEST_KEY, create)).toBe(existing);
+    expect(create).not.toHaveBeenCalled();
+  });
 });
 
 describe("resolveGlobalMap", () => {
@@ -36,4 +45,11 @@ describe("resolveGlobalMap", () => {
 
     expect(first).toBe(second);
   });
+
+  it("preserves existing map contents across repeated resolution", () => {
+    const map = resolveGlobalMap<string, number>(TEST_MAP_KEY);
+    map.set("a", 1);
+
+    expect(resolveGlobalMap<string, number>(TEST_MAP_KEY).get("a")).toBe(1);
+  });
 });

src/shared/string-sample.test.ts

@@ -4,6 +4,7 @@ import { summarizeStringEntries } from "./string-sample.js";
 describe("summarizeStringEntries", () => {
   it("returns emptyText for empty lists", () => {
     expect(summarizeStringEntries({ entries: [], emptyText: "any" })).toBe("any");
+    expect(summarizeStringEntries({ entries: null })).toBe("");
   });
 
   it("joins short lists without a suffix", () => {
@@ -18,4 +19,27 @@ describe("summarizeStringEntries", () => {
       }),
     ).toBe("a, b, c, d (+1)");
   });
+
+  it("uses a floored limit and clamps non-positive values to one entry", () => {
+    expect(
+      summarizeStringEntries({
+        entries: ["a", "b", "c"],
+        limit: 2.8,
+      }),
+    ).toBe("a, b (+1)");
+    expect(
+      summarizeStringEntries({
+        entries: ["a", "b", "c"],
+        limit: 0,
+      }),
+    ).toBe("a (+2)");
+  });
+
+  it("uses the default limit when none is provided", () => {
+    expect(
+      summarizeStringEntries({
+        entries: ["a", "b", "c", "d", "e", "f", "g"],
+      }),
+    ).toBe("a, b, c, d, e, f (+1)");
+  });
 });